Fitter MCP
The Fitter MCP server enables AI agents to extract structured JSON from websites, APIs, files, and PDFs using declarative configurationsβno coding required. All execution happens locally with no third-party API.
fitter_config_reference: Get a condensed reference of the config format to help author new configs.fitter_run: Run an inline config (JSON/YAML) to scrape/parse data, with optional dynamic input via placeholders.fitter_run_file: Run a config from a local file and get the extracted JSON.fitter_run_url: Run a config downloaded from an HTTP(S) URL (e.g., raw GitHub link) and get the extracted JSON.fitter_validate_config: Validate a config structure, data source, and expressions without executing.
Configs support multiple data sources (HTTP, headless browser, static, file), parsing formats (JSON, CSS, XPath, XML, PDF), and parameterization via placeholders.
Fitter β web data for AI agents
Fitter turns any website or API into structured JSON β declaratively. One JSON/YAML config describes where the data lives (HTTP request, headless browser, file, static value) and what to extract (JSON paths, CSS selectors, XPath). No code, no brittle scraping scripts.
π Try it in your browser β the real engine compiled to WebAssembly: live examples, a visual config builder, no install.
Because configs are plain data, LLMs can author them. The built-in MCP server lets Claude Code, Claude Desktop, or any MCP client write and run scraping pipelines on your machine, on demand:
"Get the top 5 HackerNews stories with titles and scores" β the model authors a fitter config, validates it, runs it locally, and gets clean JSON back.
One engine, five ways to use it:
π€ Fitter MCP | MCP server exposing fitter to Claude Code, Claude Desktop and any MCP client |
π§ Fitter Agent | AI-powered CLI: natural language β config β executed result |
π₯ Fitter CLI | run configs locally for test/debug/home usage |
π¦ Fitter Lib | embed the engine in your own Go program |
βοΈ Fitter | long-running service mode with scheduling & notifications |
Why fitter for AI agents?
Declarative & auditable β the agent produces a config you can read, save and re-run, not throwaway code
Local-first β all fetching happens on your machine; no third-party scraping API, no keys, no per-request billing
Batteries included β HTTP client, headless browser (Playwright/Chromium/Docker), JSON/HTML/XML/XPath/PDF parsing, pagination, cached references, host rate-limits β in a single static binary
Reusable β what the agent authored today becomes tomorrow's cron job or service config
How to use Fitter_MCP
Fitter MCP is a Model Context Protocol server (stdio transport) which lets any MCP client β Claude Code, Claude Desktop, IDE assistants, custom agents β run Fitter configs and get structured JSON back.
Quick start (Claude Desktop β one click)
Download fitter-mcp-<os>-<arch>.mcpb from the release page and open it β Claude Desktop installs the server automatically.
Quick start (Claude Code)
# 1. get the binary: download fitter_mcp_<version>-<os>-<arch> from the release page
# https://github.com/PxyUp/fitter/releases β or build it from source:
go build -o fitter_mcp ./cmd/mcp
# 2. register it once, available in every project
claude mcp add fitter -s user -- "$(pwd)/fitter_mcp"Then just ask:
Get the top 5 HackerNews stories with titles and scores using fitter
The model calls fitter_config_reference, authors a config, optionally checks it with fitter_validate_config and executes it via fitter_run β all data fetching happens locally on your machine. For a ready-made pipeline try examples/config_morning_briefing.json:
Run examples/config_morning_briefing.json with fitter and give me the briefing
Register in Claude Desktop
{
"mcpServers": {
"fitter": {
"command": "/path/to/fitter_mcp"
}
}
}Tools
Tool | Description |
| Run a Fitter config passed inline (JSON or YAML string) and return the extracted data as JSON. Accepts an optional |
| Same as |
| Same as |
| Validate a config without executing it (structure, |
| Return a condensed reference of the whole config format (connectors, parsers, model/field schema, placeholders, notifiers, references, limits) with working examples, so the model can author configs without external docs |
The reference is also exposed as MCP resource fitter://config-reference for clients that support resources.
The config format is exactly the same as for Fitter_CLI: a top-level object with item (required), limits and references. Notifiers work too (the result is additionally pushed to http/telegram/redis/file/console); trigger_config and http_server are service-mode only and are ignored in MCP calls.
Remote / hosted mode (streamable HTTP)
By default fitter_mcp talks stdio. Pass --http to serve the streamable HTTP transport instead β for a shared team server, a container, or any remote deployment:
# serve MCP at http://<host>:8080/mcp (health probe at /healthz)
FITTER_MCP_AUTH_TOKEN=my-secret fitter_mcp --http :8080
# register the remote endpoint in Claude Code
claude mcp add --transport http fitter http://localhost:8080/mcp --header "Authorization: Bearer my-secret"--http <addr>(envFITTER_MCP_HTTP_ADDR) β listen address; stdio mode when emptyFITTER_MCP_AUTH_TOKENβ when set, every/mcprequest must sendAuthorization: Bearer <token>; without it the endpoint is unauthenticated, so bind to localhost or put it behind a proxy--stateless(envFITTER_MCP_STATELESS=true) β no per-session state, so replicas can sit behind a load balancer without sticky sessions
The server shuts down gracefully on SIGINT/SIGTERM.
Docker
A slim multi-arch image (linux/amd64 + linux/arm64) ships with every release:
# hosted HTTP mode
docker run --rm -p 8080:8080 \
-e FITTER_MCP_HTTP_ADDR=:8080 \
-e FITTER_MCP_AUTH_TOKEN=my-secret \
ghcr.io/pxyup/fitter-mcp:latest
# or stdio mode, spawned by the MCP client
claude mcp add fitter -s user -- docker run --rm -i ghcr.io/pxyup/fitter-mcp:latestThe slim image contains only the fitter binary and CA certificates: server/static/file connectors work, browser connectors (chromium/docker/playwright) do not.
For browser-based configs use the playwright variant, which bundles Playwright with Chromium, Firefox and WebKit (matched to the playwright-go version fitter is built against, so no "install": true is needed in configs):
docker run --rm -i ghcr.io/pxyup/fitter-mcp:playwright # stdio mode
# per-release tag: ghcr.io/pxyup/fitter-mcp:vX.Y.Z-playwrightIt is built from Dockerfile.mcp-playwright; build with --build-arg PLAYWRIGHT_BROWSERS=chromium for a smaller Chromium-only image.
OAuth2 accounts in Docker
Both images ship fitter_cli, so the one-time OAuth2 login can run inside the container. Store the token on a volume mounted at /tokens (pre-created writable in the image) and share it with the MCP server:
# one-time login, device flow: no ports needed β open the printed url on any device
docker run --rm -it -v fitter-tokens:/tokens --entrypoint fitter_cli \
ghcr.io/pxyup/fitter-mcp:latest \
auth --provider github --client-id <ID> --client-secret <SECRET> --token-file /tokens/github.json
# or browser flow (device flow not enabled for the app): publish the callback port and
# bind on 0.0.0.0 so the published port reaches the listener; the browser still visits 127.0.0.1
docker run --rm -it -p 8988:8988 -e FITTER_AUTH_LISTEN=0.0.0.0 \
-v fitter-tokens:/tokens --entrypoint fitter_cli ghcr.io/pxyup/fitter-mcp:latest \
auth --provider github --client-id <ID> --client-secret <SECRET> --token-file /tokens/github.json
# then run the MCP server with the same volume; configs reference "token_file": "/tokens/github.json"
# stdio mode (spawned by the MCP client, no port):
docker run --rm -i -v fitter-tokens:/tokens ghcr.io/pxyup/fitter-mcp:latest
# hosted HTTP mode (MCP endpoint on 8080, like the run examples above):
docker run --rm -p 8080:8080 -v fitter-tokens:/tokens \
-e FITTER_MCP_HTTP_ADDR=:8080 \
-e FITTER_MCP_AUTH_TOKEN=my-secret \
ghcr.io/pxyup/fitter-mcp:latestNote: 8988 is only for the one-time browser-flow login; the MCP server itself needs no port in stdio mode and only 8080 in hosted HTTP mode.
Logged-in browser sessions in Docker
Browser sessions need the playwright image (the slim one has no browsers). The one-time headed login needs a display, so run it on the host, then bind-mount the session dir into the container (the image pre-creates a writable /sessions):
# on the host: log in once, save the session
fitter_cli browser-login --url https://example.com/login --storage-state ~/.fitter/sessions/example.json
# run the MCP server with the sessions dir mounted; configs reference "storage_state_file": "/sessions/example.json"
docker run --rm -i -v ~/.fitter/sessions:/sessions ghcr.io/pxyup/fitter-mcp:playwrightUse a bind mount (not a named volume): the container writes refreshed cookies back after every run, so the host copy stays current and can be re-extended with browser-login at any time.
The volume must stay writable for the server: rotated refresh tokens are written back on every refresh.
Environment variables
FITTER_PLUGINS - string[""] - path for plugins folder, same as the
--pluginsflag of Fitter/Fitter_CLIFITTER_MCP_HTTP_ADDR - string[""] - listen address for remote mode, same as
--httpFITTER_MCP_AUTH_TOKEN - string[""] - bearer token protecting the HTTP endpoint
FITTER_MCP_STATELESS - bool[false] - stateless HTTP transport, same as
--stateless
Recipes
Complete, tested configs showing the main patterns. All of them run unchanged via Fitter_MCP (fitter_run_file), Fitter_CLI or the library β more in examples/.
Scrape a page that has no API, enrich from one that does
GitHub trending has no official API β scrape the HTML for repo slugs (html_attribute reads the href), then fan each one out into the GitHub REST API with {PL}:
examples/config_github_trending.json
{
"item": {
"connector_config": {
"response_type": "HTML",
"url": "https://github.com/trending",
"server_config": { "method": "GET", "headers": { "User-Agent": "Mozilla/5.0 (fitter demo)" } }
},
"model": {
"array_config": {
"root_path": "article.Box-row h2 a",
"length_limit": 5,
"item_config": {
"field": {
"type": "string",
"html_attribute": "href",
"generated": { "model": {
"type": "object",
"connector_config": {
"response_type": "json",
"url": "https://api.github.com/repos{PL}",
"server_config": { "method": "GET", "headers": { "User-Agent": "fitter-demo" } },
"null_on_error": true
},
"model": { "object_config": { "fields": {
"repo": { "base_field": { "type": "string", "path": "full_name" } },
"stars": { "base_field": { "type": "int", "path": "stargazers_count" } },
"language": { "base_field": { "type": "string", "path": "language" } }
} } }
} }
}
}
}
}
},
"limits": { "host_request_limiter": { "api.github.com": 2 } }
}[{"repo": "block/buzz", "stars": 6214, "language": "Rust"}, {"repo": "koala73/worldmonitor", "stars": 71179, "language": "TypeScript"}]Join on a JSON field with an expression
When array items are objects, the join key lives inside them β pull it out with {{{FromExp=...}}} (expr-lang over fRes, the current item). Book search β author details, search query supplied via input:
examples/config_book_authors.json
"url": "https://openlibrary.org/authors/{{{FromExp=fromJSON(fRes).author_key[0]}}}.json"./fitter_cli --path=examples/config_book_authors.json --input=dune[{"title": "Dune", "year": 1965, "author": {"name": "Frank Herbert", "born": "8 October 1920", "died": "11 February 1986"}}]Write results to a local file
The file_storage generated field turns fields into writes β top-5 crypto coins appended to a CSV, one row per item. Bare {{{json.path}}} placeholders read the current item; {HUMAN_INDEX} stamps the 1-based rank (items are processed in parallel, so appends land in completion order β sort by the rank column):
examples/config_crypto_csv.json
"file_storage": {
"content": "{HUMAN_INDEX},{{{name}}},{{{current_price}}},{{{price_change_percentage_24h}}}\n",
"file_name": "coins.csv",
"path": "/tmp/fitter-report",
"append": true
}$ sort -n /tmp/fitter-report/coins.csv
1,Bitcoin,64778,-2.3
2,Ethereum,1881.01,-3.4
3,Tether,0.999265,0Extract text from a PDF
response_type: "pdf" turns any fetched PDF into a JSON document β {"text": "...", "pages": ["..."], "total_pages": N} β so regular JSON paths (text, pages.0) and expressions work on it. The Bitcoin whitepaper, page count plus a trimmed intro:
{
"item": {
"connector_config": {
"response_type": "pdf",
"url": "https://bitcoin.org/bitcoin.pdf",
"server_config": { "method": "GET" }
},
"model": {
"object_config": {
"fields": {
"total_pages": { "base_field": { "type": "int", "path": "total_pages" } },
"intro": {
"base_field": {
"type": "string",
"path": "pages.0",
"generated": {
"calculated": {
"type": "string",
"expression": "trim(fRes[:100]) + \"...\""
}
}
}
}
}
}
}
}
}{"intro": "Bitcoin: A Peer-to-Peer Electronic Cash SystemSatoshi Nakamotosatoshin@gmx.comwww.bitcoin.orgAbstrac...", "total_pages": 9}Way to collect information
Server - parsing response from some API's or http request(usage of http.Client)
Browser - emulate real browser using chromium + docker + playwright/cypress and get DOM information
Static - parsing static string as data
Format which can be parsed
JSON - parsing JSON to get specific information
XML - parsing xml tree to get specific information
HTML - parsing dom tree to get specific information
XPath - parsing dom tree to get specific information but by xpath
PDF - extracting text from PDF documents; the content is exposed as JSON
{"text": "...", "pages": ["..."], "total_pages": N}so regular JSON paths liketextorpages.0work
Use like a library
go get github.com/PxyUp/fitterpackage main
import (
"fmt"
"github.com/PxyUp/fitter/lib"
"github.com/PxyUp/fitter/pkg/config"
"log"
"net/http"
)
func main() {
res, err := lib.Parse(&config.Item{
ConnectorConfig: &config.ConnectorConfig{
ResponseType: config.Json,
Url: "https://random-data-api.com/api/appliance/random_appliance",
ServerConfig: &config.ServerConnectorConfig{
Method: http.MethodGet,
},
},
Model: &config.Model{
ObjectConfig: &config.ObjectConfig{
Fields: map[string]*config.Field{
"my_id": {
BaseField: &config.BaseField{
Type: config.Int,
Path: "id",
},
},
"generated_id": {
BaseField: &config.BaseField{
Generated: &config.GeneratedFieldConfig{
UUID: &config.UUIDGeneratedFieldConfig{},
},
},
},
"generated_array": {
ArrayConfig: &config.ArrayConfig{
RootPath: "@this|@keys",
ItemConfig: &config.ObjectConfig{
Field: &config.BaseField{
Type: config.String,
},
},
},
},
},
},
},
}, nil, nil, nil, nil)
if err != nil {
log.Fatal(err)
}
fmt.Println(res.ToJson())
}
Output:
{
"generated_array": ["id","uid","brand","equipment"],
"my_id": 6000,
"generated_id": "26b08b73-2f2e-444d-bcf2-dac77ac3130e"
}Use lib.ParseCtx(ctx, ...) to pass a context.Context: cancelling it aborts in-flight fetches (HTTP requests, headless browsers, docker containers) and applies deadlines end-to-end. lib.Parse is equivalent to lib.ParseCtx(context.Background(), ...).
How to use Fitter
Download latest version from the release page
or locally:
go run cmd/fitter/main.go --path=./examples/config_api.jsonArguments
--path - string[""] - path for the configuration of the Fitter
--url - string[""] - url for the configuration of the Fitter
--verbose - bool[false] - enable logging
--plugins - string[""] - path for plugins for Fitter
--log-level - enum["info", "error", "debug", "fatal"] - set log level(only if verbose set to true)
How to use Fitter_CLI
Download latest version from the release page
or locally:
go run cmd/cli/main.go --path=./examples/cli/config_cli.jsonArguments
--path - string[""] - path for the configuration of the Fitter_CLI
--url - string[""] - url for the configuration of the Fitter_CLI
--copy - bool[false] - copy information into clipboard
--pretty - bool[true] - make readable result(also affect on copy)
--verbose - bool[false] - enable logging
--omit-error-pretty - bool[false] - Provide pure value if pretty is invalid
--plugins - string[""] - path for plugins for Fitter
--log-level - enum["info", "error", "debug", "fatal"] - set log level(only if verbose set to true)
--input - string[""] - specify input value for formatting. Examples:
--input=\""124"\"--input=124--input='{"test": 5}'
./fitter_cli_${VERSION} --path=./examples/cli/config_cli.json --copy=truefitter_cli auth β connect an OAuth2 account
One-time interactive login which stores a (refresh) token for the oauth2 connector config:
# device flow (default when the provider supports it): no callback, works headless
./fitter_cli_${VERSION} auth --provider github --client-id <ID> --client-secret <SECRET> --token-file ~/.fitter/tokens/github.json
# custom provider without preset
./fitter_cli_${VERSION} auth --auth-url https://.../authorize --token-url https://.../token --client-id <ID> --token-file ./token.jsonArguments:
--provider - preset with known endpoints:
github|google|microsoft|gitlab|spotify--client-id / --client-secret - OAuth2 app credentials (some device flows work without secret)
--token-file - where to store the received token (0600 permissions); reference the same path in
oauth2.token_file--flow -
auto(device if available, else browser),device(visit a url + enter a code) orbrowser(localhost callback with PKCE, default port 8988 β registerhttp://127.0.0.1:8988/callbackas the app callback url)--scopes - comma separated scopes
--auth-url/--token-url/--device-auth-url/--auth-style - endpoint overrides for providers without preset
--port - int[8988] - browser flow callback port (env
FITTER_AUTH_PORT); with the default the callback url to register at the provider ishttp://127.0.0.1:8988/callback--listen - browser flow bind address, default
127.0.0.1; set0.0.0.0inside a container so the published port reaches the listener (envFITTER_AUTH_LISTEN)--redirect-url - callback url registered at the provider when it differs from the listen address, e.g. docker port mapping (env
FITTER_AUTH_REDIRECT_URL)--no-browser - only print the authorization url
Running inside Docker: see OAuth2 accounts in Docker.
After login the command prints the ready-to-use oauth2 config block. The connector refreshes the access token automatically and writes rotated refresh tokens back to the token file, so the login is needed only once.
fitter_cli browser-login β reuse a real login session
For sites without an API/OAuth: log in once by hand in a real (headed) browser window β any auth scheme works, including passwords, 2FA, SSO and captchas β and save the session for headless scraping via storage_state_file:
./fitter_cli_${VERSION} browser-login --url https://example.com/login --storage-state ~/.fitter/sessions/example.json
# a browser window opens; log in, then press Enter in the terminal to save the sessionArguments:
--url - login page to open (required)
--storage-state - where to save the session (cookies + localStorage, 0600 permissions); reference the same path in
playwright.storage_state_file(required)--browser - enum["Chromium", "FireFox", "WebKit"] default "Chromium"; use the same value as the scraping config β sites may bind sessions to the browser fingerprint
--install - bool[false] - install playwright browsers first
--indexeddb - bool[false] - include IndexedDB in the snapshot (Firebase Auth and similar)
Re-running the command loads the existing state first, so you can extend/refresh a session without logging in from scratch. The scraping connector also writes refreshed cookies back after every run, keeping the session alive as long as it is used regularly. Needs a display: inside Docker run this command on the host and mount the file β see browser sessions in Docker.
Examples:
Server version HackerNews + Quotes + Guardian News - using API + HTML + XPath parsing
Chromium version Guardian News + Quotes - using HTML parsing + browser emulation
Docker version Docker version: Guardian News + Quotes - using HTML parsing + browser from Docker image
Playwright version Playwright version: Guardian News + Quotes - using HTML parsing + browser from Playwright framework
Playwright version Playwright version: England Cities + Weather - using HTML + XPath parsing + browser from Playwright framework
JSON version Generate pagination - using static connector for generate pagination array
Server version Get current time - get time from url and format it
How to use Fitter_Agent
Fitter Agent is an AI-powered CLI that uses Claude to convert natural language requests into Fitter configurations and execute them automatically.
Download latest version from the release page
or locally:
export ANTHROPIC_API_KEY=<your-anthropic-api-key>
go run cmd/agent/main.goArguments
--api-key - string[""] - Anthropic API key. Prefer the
ANTHROPIC_API_KEYenvironment variable so the key does not end up in your shell history--model - string["claude-opus-4-8"] - Claude model to use
--effort - enum["low", "medium", "high", "xhigh", "max"] - reasoning effort, default "high". Lower it for faster/cheaper configs, raise it for harder extractions
--verbose - bool[false] - enable logging
--log-level - enum["info", "error", "debug", "fatal"] - set log level
--plugins - string[""] - path for plugins for Fitter
--chromium-limit - uint[0] - limit concurrent Chromium instances
--docker-limit - uint[0] - limit concurrent Docker containers
--playwright-limit - uint[0] - limit concurrent Playwright instances
How it works
βββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββ
β 1. User enters natural language request β
β "Get top 5 HackerNews stories with titles and scores" β
β β β
β 2. Claude returns a config in a schema-constrained response β
β β β
β 3. Agent validates it; on failure the error is handed back β
β to Claude to repair (up to 3 attempts) β
β β β
β 4. Agent displays config and asks for confirmation β
β β β
β 5. On confirmation, executes via lib.Parse() β
β β β
β 6. Returns structured JSON result β
βββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββRefining a config
The agent keeps the conversation, so after a config is generated you can just say what to change instead of restating the whole request:
> Get top 3 HackerNews stories with titles and scores
refine> Only return 5 items and also include the article URLUse new to forget the current config and start a fresh session.
Interactive REPL Commands
help - show help message
new/reset - forget the current config and start fresh
clear - clear the screen
exit/quit/q - exit the agent
Example Session
$ export ANTHROPIC_API_KEY=sk-ant-...
$ ./fitter_agent
ββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββ
β Fitter Agent - AI-Powered Data Extraction β
ββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββ
Describe what you want to extract. Follow-up messages refine the
previous config. Type 'help' for commands.
> Get top 3 HackerNews stories with titles and scores
ββ Generated Fitter Config βββββββββββββββββββββββββββββββββββββββ
{
"item": {
"connector_config": {
"response_type": "json",
"url": "https://hacker-news.firebaseio.com/v0/topstories.json",
"server_config": { "method": "GET" }
},
"model": {
"array_config": {
"root_path": "@this",
"length_limit": 3,
"item_config": {
"fields": {
"id": { "base_field": { "type": "int" } },
"story": {
"base_field": {
"type": "int",
"generated": {
"model": {
"type": "object",
"connector_config": {
"response_type": "json",
"url": "https://hacker-news.firebaseio.com/v0/item/{PL}.json",
"server_config": { "method": "GET" }
},
"model": {
"object_config": {
"fields": {
"title": { "base_field": { "type": "string", "path": "title" } },
"score": { "base_field": { "type": "int", "path": "score" } }
}
}
}
}
}
}
}
}
}
}
}
}
}
βββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββ
Execute this config? [y/n]: y
ββ Result ββββββββββββββββββββββββββββββββββββββββββββββββββββββββ
[
{
"id": 46740029,
"story": { "title": "Show HN: Open-source project", "score": 161 }
},
{
"id": 46737630,
"story": { "title": "Interesting article", "score": 237 }
},
{
"id": 46735644,
"story": { "title": "New technology release", "score": 192 }
}
]
βββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββ
> exit
Goodbye!Example Requests
Request | What it does |
| Fetches current BTC price |
| HTML scraping with CSS selectors |
| Nested API calls |
| Simple API extraction |
| Web scraping |
Supported Capabilities
The agent can generate configs for:
JSON APIs - REST APIs with GET/POST methods
HTML Scraping - CSS selector-based extraction
XPath Scraping - XPath-based extraction
Nested API Calls - Fetch details for each item in a list
Browser Emulation - Playwright for JS-rendered pages
Formatted Fields - URL templates with placeholders
Array Limiting - Limit results to N items
Configuration
Connector
It is the way how you fetch the data
type ConnectorConfig struct {
ResponseType ParserType `json:"response_type" yaml:"response_type"`
Url string `json:"url" yaml:"url"`
Attempts uint32 `json:"attempts" yaml:"attempts"`
NullOnError bool `yaml:"null_on_error" json:"null_on_error"`
StaticConfig *StaticConnectorConfig `json:"static_config" yaml:"static_config"`
IntSequenceConfig *IntSequenceConnectorConfig `json:"int_sequence_config" yaml:"int_sequence_config"`
ServerConfig *ServerConnectorConfig `json:"server_config" yaml:"server_config"`
BrowserConfig *BrowserConnectorConfig `yaml:"browser_config" json:"browser_config"`
PluginConnectorConfig *PluginConnectorConfig `json:"plugin_connector_config" yaml:"plugin_connector_config"`
ReferenceConfig *ReferenceConnectorConfig `yaml:"reference_config" json:"reference_config"`
FileConfig *FileConnectorConfig `json:"file_config" yaml:"file_config"`
}NullOnError[false] - if set to true then all errors a ignored
ResponseType - enum["HTML", "json", "xpath", "XML", "pdf"] - in which format data comes from the connector
Attempts - how many attempts to use for fetch data by connector
Url - define which address to request. Important: can be with inject of the parent value as a string
https://api.open-meteo.com/v1/forecast?latitude={{{latitude}}}&longitude={{{longitude}}}&hourly=temperature_2m&forecast_days=1
Config can be one of:
Example:
{
"response_type": "xpath",
"attempts": 3,
"url": "https://openweathermap.org/find?q={PL}",
"browser_config": {
"playwright": {
"timeout": 30,
"wait": 30,
"install": false,
"browser": "Chromium"
}
}
}PluginConnectorConfig
Connector can be defined via plugin system. For use that you need apply next flags to Fitter/Cli(location of the plugins):
... --plugins=./examples/plugin--plugins - looking for all files with ".so" extension in provided folder(subdirs excluded)
type PluginConnectorConfig struct {
Name string `json:"name" yaml:"name"`
Config json.RawMessage `json:"config" yaml:"config"`
}{
"name": "connector",
"config": {
"name": "Elon"
}
}Name - name of the plugin
Config - json config of the plugin
How to build plugin
Build plugin
go build -buildmode=plugin -gcflags="all=-N -l" -o examples/plugin/connector.so examples/plugin/connector/connector.goMake sure you export Plugin variable which implements pl.ConnectorPlugin interface
Example for CLI:
https://github.com/PxyUp/fitter/blob/master/examples/cli/config_plugin.json#L5
Plugin example:
package main
import (
"context"
"encoding/json"
"fmt"
"github.com/PxyUp/fitter/pkg/config"
"github.com/PxyUp/fitter/pkg/logger"
"github.com/PxyUp/fitter/pkg/builder"
pl "github.com/PxyUp/fitter/pkg/plugins/plugin"
)
var (
_ pl.ConnectorPlugin = &plugin{}
Plugin plugin
)
type plugin struct {
log logger.Logger
Name string `json:"name" yaml:"name"`
}
func (pl *plugin) Get(ctx context.Context, parsedValue builder.Interfacable, index *uint32, input builder.Interfacable) ([]byte, error) {
return []byte(fmt.Sprintf(`{"name": "%s"}`, pl.Name)), nil
}
func (pl *plugin) SetConfig(cfg *config.PluginConnectorConfig, logger logger.Logger) {
pl.log = logger
if cfg.Config != nil {
err := json.Unmarshal(cfg.Config, pl)
if err != nil {
pl.log.Errorw("cant unmarshal plugin configuration", "error", err.Error())
return
}
}
}ReferenceConnectorConfig
Connector which allow get prefetched data from references
type ReferenceConnectorConfig struct {
Name string `yaml:"name" json:"name"`
}Example
https://github.com/PxyUp/fitter/blob/master/examples/cli/config_ref.json#L66
Name - reference name from references map
IntSequenceConnectorConfig
Improved version of static connector which generate int sequence as result
type IntSequenceConnectorConfig struct {
Start int `json:"start" yaml:"start"`
End int `json:"end" yaml:"end"`
Step int `json:"step" yaml:"step"`
}Start[0] - start point for generation(included)
End[0] - end point for generation(excluded from final result like range in any lang)
Step[1] - interval for sequence
Example
{
"start": 0,
"end": 2
// Generate [0, 1]
}FileConnectorConfig
Connector type which fetch data from provided file
type FileConnectorConfig struct {
Path string `yaml:"path" json:"path"`
UseFormatting bool `yaml:"use_formatting" json:"use_formatting"`
}Path - file path. Support formatting
UseFormatting[false] - use formatting file content or not
StaticConnectorConfig
Connector type which fetch data from provided string
type StaticConnectorConfig struct {
Value string `json:"value" yaml:"value"`
Raw json.RawMessage `json:"raw" yaml:"raw"`
}Value - static string as data, can be html, json
Raw - accept raw json. Example. Also support formatting
Example:
https://github.com/PxyUp/fitter/blob/master/examples/cli/config_static_connector.json#L5
{
"value": "[1,2,3,4,5]"
}ServerConnectorConfig
Connector type which fetch data using golang http.Client(server side request like curl)
type ServerConnectorConfig struct {
Method string `json:"method" yaml:"method"`
Headers map[string]string `yaml:"headers" json:"headers"`
Timeout uint32 `yaml:"timeout" json:"timeout"`
JsonRawBody json.RawMessage `json:"json_raw_body" yaml:"json_raw_body"`
Body string `yaml:"body" json:"body"`
Proxy *ProxyConfig `yaml:"proxy" json:"proxy"`
OAuth2 *OAuth2Config `yaml:"oauth2" json:"oauth2"`
}Method - supported all http methods: GET, POST, PUT, DELETE, PATCH, OPTIONS, HEAD
Headers - predefine headers for using during request can be injected into key/value
Timeout[sec] - default 60sec timeout or used provided
Body - body of the request, parsed value can be injected
JsonRawBody - body of the request in json format; value can be injected
Proxy - setup proxy for request config
OAuth2 - fetch/refresh an access token automatically and send it as
Authorizationheader config
Example:
{
"method": "GET",
"proxy": {
"server": "http://localhost:8080",
"username": "pyx"
}
}OAuth2 config
Automatically obtains an access token before the request and injects it as the Authorization header (overriding one set via headers). Tokens are cached in memory and refreshed before expiry; on a 401 response the cached token is dropped and the request is retried once with a fresh one.
type OAuth2Config struct {
TokenUrl string `json:"token_url" yaml:"token_url"`
GrantType OAuth2GrantType `json:"grant_type" yaml:"grant_type"`
ClientId string `json:"client_id" yaml:"client_id"`
ClientSecret string `json:"client_secret" yaml:"client_secret"`
Scopes []string `json:"scopes" yaml:"scopes"`
RefreshToken string `json:"refresh_token" yaml:"refresh_token"`
EndpointParams map[string]string `json:"endpoint_params" yaml:"endpoint_params"`
AuthStyle string `json:"auth_style" yaml:"auth_style"`
TokenFile string `json:"token_file" yaml:"token_file"`
}TokenUrl - token endpoint URL. Also support formatting
GrantType - enum["client_credentials", "refresh_token"], default is "client_credentials". Use "refresh_token" for APIs where the user consented once (Google, Microsoft, ...) and you hold a long-lived refresh token
ClientId/ClientSecret - client credentials. Also support formatting, e.g.
{{{FromEnv=CLIENT_SECRET}}}Scopes - requested scopes
RefreshToken - required for the "refresh_token" grant. Also support formatting
EndpointParams - extra token endpoint parameters (e.g.
audiencefor Auth0), "client_credentials" grant onlyAuthStyle - enum["", "header", "params"] - how client credentials are passed to the token endpoint: basic auth header or request body; empty means auto detect
TokenFile - optional path (supports
~/) for persisting tokens between runs; the stored token is preferred over RefreshToken and rotated refresh tokens are written back β required for providers with single-use refresh tokens (GitHub Apps and similar). Create it with fitter_cli auth
Example:
{
"method": "GET",
"oauth2": {
"token_url": "https://oauth2.googleapis.com/token",
"grant_type": "refresh_token",
"client_id": "{{{FromEnv=GOOGLE_CLIENT_ID}}}",
"client_secret": "{{{FromEnv=GOOGLE_CLIENT_SECRET}}}",
"refresh_token": "{{{FromEnv=GOOGLE_REFRESH_TOKEN}}}"
}
}Proxy config
type ProxyConfig struct {
// Proxy to be used for all requests. HTTP and SOCKS proxies are supported, for example
// `http://myproxy.com:3128` or `socks5://myproxy.com:3128`. Short form `myproxy.com:3128`
// is considered an HTTP proxy.
Server string `json:"server" yaml:"server"`
// Optional username to use if HTTP proxy requires authentication.
Username string `json:"username" yaml:"username"`
// Optional password to use if HTTP proxy requires authentication.
Password string `json:"password" yaml:"password"`
}Server - address with schema of proxy server. Also support formatting
Username - username for proxy(can be empty). Also support formatting
Password - password for proxy(can be empty). Also support formatting
{
"server": "http://localhost:8080",
"username": "pyx"
}Environment variables
FITTER_HTTP_WORKER - int[1000] - default concurrent HTTP workers
BrowserConnectorConfig
Connector type which emulate fetching of data via browser
type BrowserConnectorConfig struct {
Chromium *ChromiumConfig `json:"chromium" yaml:"chromium"`
Docker *DockerConfig `json:"docker" yaml:"docker"`
Playwright *PlaywrightConfig `json:"playwright" yaml:"playwright"`
}Config can be one of:
Chromium - use local installed Chromium for fetch data
Docker - use docker as service for spin up container for fetch data
Playwright - use playwright framework for fetch data
Example:
{
"docker": {
"wait": 10000,
"image": "docker.io/zenika/alpine-chrome:with-node",
"entry_point": "chromium-browser",
"purge": true
}
}Chromium
Use locally installed Chromium for fetch the data
type ChromiumConfig struct {
Path string `yaml:"path" json:"path"`
Timeout uint32 `yaml:"timeout" json:"timeout"`
Wait uint32 `yaml:"wait" json:"wait"`
Flags []string `yaml:"flags" json:"flags"`
}Path - path to binary of Chromium
Timeout[sec] - timeout for execution of the chromium
Wait[msec] - timeout of page loading
Flags - flags for Chromium default: "--headless", "--proxy-auto-detect", "--temp-profile", "--incognito", "--disable-logging", "--disable-extensions", "--no-sandbox"
Example:
{
"path": "/Applications/Google Chrome.app/Contents/MacOS/Google Chrome",
"wait": 10000
}Docker
Use Docker for spin up container for fetch data
type DockerConfig struct {
Image string `yaml:"image" json:"image"`
EntryPoint string `json:"entry_point" yaml:"entry_point"`
Timeout uint32 `yaml:"timeout" json:"timeout"`
Wait uint32 `yaml:"wait" json:"wait"`
Flags []string `yaml:"flags" json:"flags"`
Purge bool `json:"purge" yaml:"purge"`
NoPull bool `yaml:"no_pull" json:"no_pull"`
PullTimeout uint32 `yaml:"pull_timeout" json:"pull_timeout"`
}Docker default image: docker.io/zenika/alpine-chrome
Image - image for the docker registry(provide with registry host)
EntryPoint - cmd which will be run inside container
Timeout[sec] - timeout for run container(without pulling image)
Wait[msec] - timeout of page loading (works just for Chromium based containers)
Flags - cmd arguments for run containers, default for Chromium based: "--no-sandbox","--headless", "--proxy-auto-detect", "--temp-profile", "--incognito", "--disable-logging", "--disable-gpu"
Purge - should we remove container after work done(like docker rm)
NoPull - prevent pulling of the image
PullTimeout - define timeout for pull contains
Environment variables
DOCKER_HOST - string - (EnvOverrideHost) to set the URL to the docker server.
DOCKER_API_VERSION - string - (EnvOverrideAPIVersion) to set the version of the API to use, leave empty for latest.
DOCKER_CERT_PATH - string - (EnvOverrideCertPath) to specify the directory from which to load the TLS certificates (ca.pem, cert.pem, key.pem).
DOCKER_TLS_VERIFY - bool - (EnvTLSVerify) to enable or disable TLS verification (off by default)
Example:
{
"wait": 10000,
"image": "docker.io/zenika/alpine-chrome:with-node",
"entry_point": "chromium-browser",
"purge": true
}Playwright
Run browsers via playwright framework
type PlaywrightConfig struct {
Browser PlaywrightBrowser `json:"browser" yaml:"browser"`
Install bool `yaml:"install" json:"install"`
Timeout uint32 `yaml:"timeout" json:"timeout"`
Wait uint32 `yaml:"wait" json:"wait"`
TypeOfWait *playwright.WaitUntilState `json:"type_of_wait" yaml:"type_of_wait"`
PreRunScript string `json:"pre_run_script" yaml:"pre_run_script"`
PostRunScript string `json:"post_run_script" yaml:"post_run_script"`
Stealth bool `json:"stealth" yaml:"stealth"`
StorageStateFile string `json:"storage_state_file" yaml:"storage_state_file"`
IndexedDB bool `json:"indexed_db" yaml:"indexed_db"`
Proxy *ProxyConfig `yaml:"proxy" json:"proxy"`
}Browser - enum["Chromium", "FireFox", "WebKit"] - which browser to use
Install - should we install browser (downloads the driver + browser matching the built-in
playwright-goversion on first use; not needed with theghcr.io/pxyup/fitter-mcp:playwrightimage, which ships them preinstalled)Timeout[sec] - timeout to run playwright
Wait[sec] - timeout of page loading
TypeOfWait - enum["load", "domcontentloaded", "networkidle", "commit"] which state of page we waiting, default is "load"
PreRunScript[""] - script which will be injected via AddInitScript and executed before any page script runs (on document creation, before navigation completes). Useful for patching the environment (navigator overrides, API stubs). Cannot access the loaded DOM. Also support placeholder {PL}
PostRunScript[""] - script which will be executed after page load, before reading content of the page. Useful for DOM interaction (clicks, scrolling). Also support placeholder {PL}
Stealth[false] - add script for trying passing bot defends
StorageStateFile[""] - path (supports
~/) to a playwright storage state json (cookies + localStorage): loaded into the browser context before navigation, written back after every run so refreshed sessions stay alive. Lets headless runs reuse a real login β create the file once with fitter_cli browser-login. Use the samebrowserfor login and scraping: sites may bind sessions to the browser fingerprint. Also support formattingIndexedDB[false] - include IndexedDB in the persisted storage state (some SPAs, e.g. Firebase Auth, keep tokens there)
Proxy - setup proxy for request config
Example
{
"timeout": 30,
"wait": 30,
"install": false,
"browser": "Chromium"
}Related MCP server: MCP Server Fetch Python
Model
With model we define result of the scrapping
type Model struct {
ObjectConfig *ObjectConfig `yaml:"object_config" json:"object_config"`
ArrayConfig *ArrayConfig `json:"array_config" yaml:"array_config"`
BaseField *BaseField `json:"base_field" yaml:"base_field"`
IsArray bool `json:"is_array" yaml:"is_array"`
}Config can be one of:
ObjectConfig - configuration of object format
ArrayConfig - configuration of array format
BaseField - configuration of single/generated field
IsArray - bool[false] - force indicate that field is array(usable in case of model field with base field)
Example:
{
"object_config": {}
}ObjectConfig
Configuration of the object and fields
type ObjectConfig struct {
Fields map[string]*Field `json:"fields" yaml:"fields"`
Field *BaseField `json:"field" yaml:"field"`
ArrayConfig *ArrayConfig `json:"array_config" yaml:"array_config"`
Condition string `json:"condition" yaml:"condition"`
}Condition - optional condition expression evaluated against the source node before resolution; when false the whole object is omitted from the parent (fields are not resolved at all)
Config can be one of:
Fields - map of each field definition; key - field name, value - configuration
Field - used for element of array; fields which will be deserialized like basic type like "string", "int" and etc (used here for case array of basic types)
ArrayConfig - used for element of array; deserialization array of array
Example:
{
"fields": {
"title": {
"base_field": {
"type": "string",
"path": "type"
}
}
}
}ArrayConfig
Configuration of the array and fields
type ArrayConfig struct {
RootPath string `json:"root_path" yaml:"root_path"`
Reverse bool `yaml:"reverse" json:"reverse"`
ItemConfig *ObjectConfig `json:"item_config" yaml:"item_config"`
LengthLimit uint32 `json:"length_limit" yaml:"length_limit"`
Condition string `json:"condition" yaml:"condition"`
ItemCondition string `json:"item_condition" yaml:"item_condition"`
StaticConfig *StaticArrayConfig `json:"static_array" yaml:"static_array"`
}RootPath - selector for find root element of the array or repeated element in case of html parsing, size of array will be amount of children element under the root
Reverse - bool[false] - indicate that need use reverse iteration(n to 1)
LengthLimit - for define size of array only for generated(not working for static)
Condition - optional condition expression evaluated against the source node before resolution; when false the whole array is omitted from the parent
ItemCondition - optional condition expression evaluated against every built item (fRes - item value, fSrc - source element, fIndex - item index); items resolving to false are dropped from the array - declarative filtering. Not applied to static_array
Config can be one of:
ItemConfig - configuration of each element of the array
StaticConfig - configuration of the static array
Example:
{
"root_path": "#content dt.quote > a",
"item_config": {
"field": {
"type": "string"
}
}
}Field
Common of the field
type Field struct {
BaseField *BaseField `json:"base_field" yaml:"base_field"`
ObjectConfig *ObjectConfig `json:"object_config" yaml:"object_config"`
ArrayConfig *ArrayConfig `json:"array_config" yaml:"array_config"`
FirstOf []*Field `json:"first_of" yaml:"first_of"`
}Config can be one of:
BaseField - fields which will be deserialized like basic type like "string", "int" and etc
ObjectConfig - in case our field in nested object
ArrayConfig - in case our field in array
FirstOf - first not empty resolved field will be selected
Example:
{
"base_field": {
"type": "string",
"path": "div.current-temp span.heading"
}
}BaseField
In case we want get some static information or generate new one
type BaseField struct {
Type FieldType `yaml:"type" json:"type"`
Path string `yaml:"path" json:"path"`
HTMLAttribute string `json:"html_attribute" yaml:"html_attribute"`
Condition string `json:"condition" yaml:"condition"`
Generated *GeneratedFieldConfig `yaml:"generated" json:"generated"`
FirstOf []*BaseField `json:"first_of" yaml:"first_of"`
}FieldType - enum["null", "boolean", "string", "int", "int64", "float", "float64", "array", "object", "html", "raw_string"] - static field for parse. Important: type html will only works from connector which return HTML (HTMLAttribute - have no effect in this case). Example
Path - selector(relative in case it is array child) for parsing
HTMLAttribute - extra value which have effect only in HTML parsing via goquery. Here you can specify which attribute need to be parsed.
Condition - optional condition expression evaluated against the extracted value (fRes/fResJson/fResRaw, fIndex; fSrc - the node the field was resolved from, siblings included); when false the field is omitted from the parent object/array instead of producing null. Evaluated before Generated, so a false condition also skips generated work (sub-requests, file downloads)
Important: by default "string" type trimmed and all special chars is replaced, if you need plain string use "raw_string"
Config can be one of or empty:
Generated - field can be generated one which custom configuration
FirstOf - first not empty resolved field will be selected
Examples
{
"generated": {
"uuid": {}
}
}{
"type": "string",
"path": "text()"
}Conditional fields
Every field can carry a condition - an expr-lang expression (predefined values). When it evaluates to anything except true the field is omitted from the output (the key/item disappears), not set to null. An invalid expression also omits the field and logs an error.
Where the condition is evaluated:
BaseField.
condition- after extraction:fResis the extracted value,fSrcthe node the field was resolved from (its siblings included) - sofSrc.on_sale == truecan gate a field on data you did not extract. A false condition skips generated work entirely (no sub-request, no file download)ObjectConfig.
condition/ ArrayConfig.condition- before resolution:fRes/fSrcare the source node (parsed value for json, text content for html)ArrayConfig.
item_condition- against every built item:fResis the item,fSrcthe source element it was built from,fIndexits index; false items are dropped - declarative array filtering. UsefSrcto filter on source attributes without adding them to the output
Filter array items - fSrc.in_stock reads the source element (not extracted into the output), fRes.price the built item:
{
"array_config": {
"root_path": "products",
"item_condition": "fSrc.in_stock && fRes.price > 0",
"item_config": {
"fields": {
"title": { "base_field": { "type": "string", "path": "title" } },
"price": { "base_field": { "type": "float", "path": "price" } }
}
}
}
}Omit a key unless the value passes a check:
{
"discount": {
"base_field": {
"type": "float",
"path": "discount_pct",
"condition": "fRes > 0"
}
}
}Special cases:
in a static array an omitted item stays
null(positions are fixed by definition, indexes never shift)if the root model config is omitted the parse result is
nullinside first_of a branch with a false condition counts as empty, so the next branch is tried
Runnable example: examples/config_conditions.json
GeneratedFieldConfig
Provide functionality of generating field on the flight
type GeneratedFieldConfig struct {
UUID *UUIDGeneratedFieldConfig `yaml:"uuid" json:"uuid"`
Static *StaticGeneratedFieldConfig `yaml:"static" json:"static"`
Formatted *FormattedFieldConfig `json:"formatted" yaml:"formatted"`
Plugin *PluginFieldConfig `yaml:"plugin" json:"plugin"`
Calculated *CalculatedConfig `yaml:"calculated" json:"calculated"`
File *FileFieldConfig `yaml:"file" json:"file"`
Model *ModelField `yaml:"model" json:"model"`
FileStorageField *FileStorageField `json:"file_storage" yaml:"file_storage"`
}Config can be one of:
UUID - generate random UUID V4
Static - generate static field
Formatted - format field
Model - model generated from the other connector and model
Plugin - plugin field
Calculated - calculated field
File - file field (for download file from server)
FileStorage - file field which can be saved to local file
Examples:
{
"uuid": {}
}https://github.com/PxyUp/fitter/blob/master/examples/cli/config_cli.json#L58
{
"model": {
"type": "array",
"model": {
"array_config": {
"root_path": "#content dt.quote > a",
"item_config": {
"field": {
"type": "string"
}
}
}
},
"connector_config": {
"response_type": "HTML",
"url": "http://www.quotationspage.com/random.php",
"attempts": 3,
"browser_config": {
"chromium": {
"path": "/Applications/Google Chrome.app/Contents/MacOS/Google Chrome",
"wait": 10000
}
}
}
}
}UUID
Generate random UUID V4 on the flight, can be used for generate uniq id
type UUIDGeneratedFieldConfig struct {
Regexp string `yaml:"regexp" json:"regexp"`
}Regexp - provide matcher which can be used for get part of generated uuid
Static
Generate static field
type StaticGeneratedFieldConfig struct {
Type FieldType `yaml:"type" json:"type"`
Value string `json:"value" yaml:"value"`
Raw json.RawMessage `json:"raw" yaml:"raw"`
}Type - enum["null", "boolean", "string", "int","int64","float","float64", "array", "object"] - type of the field
Value - string value of the field
Raw - pure json value of the field
Example
{
"type": "int",
"value": "65"
}{
"type": "array",
"value": "[65,45]"
}{
"type": "array",
"raw": [65,45]
}Formatted Field Config
Generate formatted field which will pass value from parent base field
type FormattedFieldConfig struct {
Template string `yaml:"template" json:"template"`
}Example: https://github.com/PxyUp/fitter/blob/master/examples/cli/config_cli.json#L98
{
"template": "https://news.ycombinator.com/item?id={PL}"
}File Storage Field
Field can be used for store field result as local file
type FileStorageField struct {
Content string `json:"content" yaml:"content"`
Raw json.RawMessage `yaml:"raw" yaml:"raw"`
FileName string `json:"file_name" yaml:"file_name"`
Path string `json:"path" yaml:"path"`
Append bool `json:"append" yaml:"append"`
}Content - template string for content. Important: can be with inject of the parent value as a string
Raw - raw json content of field. Important: can be with inject of the parent value as a string
FileName - local file name for storing file. By default, it is try get FileName from header, after that from url. Important: can be with inject of the parent value as a string.
Path - local file parent directory for storing file. Default path it is process directory. Important: can be with inject of the parent value as a string
Append[false] - append to file or not
{
"content": "{{{id}}}, {{{message}}}\n",
"append": true,
"file_name": "{{{id}}}.csv",
"path": "/Users/pxyup/fitter/examples/cli/test/csv"
}File Field
Field can be used for download file from server locally
type FileFieldConfig struct {
Config *ServerConnectorConfig `yaml:"config" json:"config"`
Url string `yaml:"url" json:"url"`
FileName string `json:"file_name" yaml:"file_name"`
Path string `json:"path" yaml:"path"`
}Config - ServerConfig use default fitter http.Client for send request
Url - url of the image. Important: URL in the connector can be with inject of the parent value as a string
FileName - local file name for storing file. By default, it is try get FileName from header, after that from url. Important: can be with inject of the parent value as a string.
Path - local file parent directory for storing file. Default path it is process directory. Important: can be with inject of the parent value as a string
Result of the field will be local file path as string
{
"url": "https://images.shcdn.de/resized/w680/p/dekostoff-gobelinstoff-panel-oriental-cat-46-x-46_P19-KP_2.jpg",
"path": "/Users/pxyup/fitter/bin",
"config": {
"method": "GET"
}
}With propagated URL (inject of the parent value as a string)
{
"url": "https://picsum.photos{PL}",
"path": "/Users/pxyup/fitter/bin",
"config": {
"method": "GET"
}
}Config example:
https://github.com/PxyUp/fitter/blob/master/examples/cli/config_image.json
https://github.com/PxyUp/fitter/blob/master/examples/cli/config_image_multiple.json
Calculated field
Field can generate different types depends from expression
type CalculatedConfig struct {
Type FieldType `yaml:"type" json:"type"`
Expression string `yaml:"expression" json:"expression"`
}Type - resulting type of expression\
Expression - expression for calculation (we use this lib for calculated expression)
Predefined values
FNull - alias for builder.Nullvalue
FNil - alias for nil
isNull(value T) - function for check is value is FNull
fRes - it is raw(with proper type) result from the parsing base field
fIndex - it is index in parent array(only if parent was array field)
fResJson - it is JSON string representation of the raw result
fResRaw - result in bytes format
fSrc - only in condition/item_condition expressions: the source node the value was resolved from (parsed value for json - siblings included, text content for html). Not available in calculated/formatted/notifier expressions
FNewLine - new line separator
{
"type": "bool",
"expression": "fRes > 500"
}Plugin field
Field can be some external plugin for fitter
type PluginFieldConfig struct {
Name string `json:"name" yaml:"name"`
Config json.RawMessage `json:"config" yaml:"config"`
}Name - name of the plugin(without extension just name)
Config - json config of the plugin
Model Field
Field type which can be generated on the flight by news model and connector
type ModelField struct {
// Type of parsing
ConnectorConfig *ConnectorConfig `yaml:"connector_config" json:"connector_config"`
// Model of the response
Model *Model `yaml:"model" json:"model"`
Type FieldType `yaml:"type" json:"type"`
Path string `yaml:"path" json:"path"`
Expression string `yaml:"expression" json:"expression"`
}ConnectorConfig - which connector to use. Important: URL in the connector can be with inject of the parent value as a string
Model - configuration of the underhood model
Type - enum["null", "boolean", "string", "int", "int64", "float", "float64", "array", "object"] - type of generated field
Path - in case we cant extract some information from generated field we can use json selector for extract
Expression - string which can be used for post processing of the Model (ignoring path field)
Examples:
https://github.com/PxyUp/fitter/blob/master/examples/cli/config_cli.json#L60
{
"type": "array",
"model": {
"array_config": {
"root_path": "#content dt.quote > a",
"item_config": {
"field": {
"type": "string"
}
}
}
}
}https://github.com/PxyUp/fitter/blob/master/examples/cli/config_weather.json#L37
{
"type": "string",
"path": "temp.temp",
"model": {
"object_config": {
"fields": {
"temp": {
"base_field": {
"type": "string",
"path": "//div[@id='forecast_list_ul']//td/b/a/@href",
"generated": {
"model": {
"type": "string",
"model": {
"object_config": {
"fields": {
"temp": {
"base_field": {
"type": "string",
"path": "div.current-temp span.heading"
}
}
}
}
},
"connector_config": {
"response_type": "HTML",
"attempts": 4,
"url": "https://openweathermap.org{PL}",
"browser_config": {
"playwright": {
"timeout": 30,
"wait": 30,
"install": false,
"browser": "FireFox",
"type_of_wait": "networkidle"
}
}
}
}
}
}
}
}
}
},
"connector_config": {
"response_type": "xpath",
"attempts": 3,
"url": "https://openweathermap.org/find?q={PL}",
"browser_config": {
"playwright": {
"timeout": 30,
"wait": 30,
"install": false,
"browser": "Chromium"
}
}
}
}Static Array Config
Provide static(fixed length) array generation
type StaticArrayConfig struct {
Items map[uint32]*Field `yaml:"items" json:"items"`
Length uint32 `yaml:"length" json:"length"`
}Items - map[uint32]*Field - key is index in array, value is field definition
Length - if set(1+) can be used for define custom length of array
Examples:
{
"0": {
"base_field": {
"type": "string",
"path": "div.current-temp span.heading"
}
}
}{
"length": 4,
"0": {
"base_field": {
"type": "string",
"path": "div.current-temp span.heading"
}
}
}{
"length": 4,
"2": {
"base_field": {
"type": "string",
"path": "div.current-temp span.heading"
}
}
}Placeholder list
{PL} - for inject value
{INDEX} - for inject index in parent array
{HUMAN_INDEX} - for inject index in parent array in human way
{{{json_path}}} - will get information from propagated "object"/"array" field
{{{RefName=SomeName}}} - get reference value by name. Example
{{{RefName=SomeName json.path}}} - get reference value by name and extract value by json path. Example
{{{FromEnv=ENV_KEY}}} - get value from environment variable
{{{FromExp=fRes + 5 + fIndex}}} - get value from the expression. Predefined values
{{{FromInput=.}}} or {{{FromInput=json.path}}} - get value from input of trigger or library
{{{FromFile=./test_file.log}}} - get value from file by path. Content of file also can contain placeholders
{{{FromURL=http://localhost:8081}}} - get response from url
Examples:
{{{FromExp="{{{FromEnv=TEST_VAL}}}" + "hello"}}}Current time is: {PL} with token from TokenRef={{{RefName=TokenRef}}} and TokenObjectRef={{{RefName=TokenObjectRef token}}}Current time is: {PL} with token from TokenRef={{{RefName=TokenRef}}} and TokenObjectRef={{{RefName=TokenObjectRef token}}}TokenRef={{{RefName=TokenRef}}} and TokenObjectRef={{{RefName=TokenObjectRef token}}} Object={{{value}}} {PL} Env={{{FromEnv=TEST_VAL}}} {INDEX} {HUMAN_INDEX}References
Special map which prefetched(before any processing) and can be user for connector or for placeholder
Can be used for:
Cache jwt token and use them in headers
Cache values
Etc
Reference
type Reference struct {
*ModelField
Expire *uint32 `yaml:"expire" json:"expire"`
}ModelField - is embedded struct, you can use same fields
Expire[sec] - duration when reference is expired after fetching. Not set => forever cached. Set to 0 => every time re-fetch. Set to n > 0 => cached for n second
For Fitter
type RefMap map[string]*Reference
type Config struct {
// Other Config Fields
Limits *Limits `yaml:"limits" json:"limits"`
References RefMap `json:"references" yaml:"references"`
}For Fitter Cli
type RefMap map[string]*Reference
type CliItem struct {
// Other Config Fields
Limits *Limits `yaml:"limits" json:"limits"`
References RefMap `json:"references" yaml:"references"`
}References - map[string]*Reference - object where is key if ReferenceName (can be user for connector or placeholder) and value is Reference
Example
https://github.com/PxyUp/fitter/blob/master/examples/cli/config_ref.json#L2
{
"references": {
"TokenRef": {
"expire": 10,
"connector_config": {
"response_type": "json",
"static_config": {
"value": "\"plain token\""
}
},
"model": {
"base_field": {
"type": "string"
}
}
},
"TokenObjectRef": {
"connector_config": {
"response_type": "json",
"static_config": {
"value": "{\"token\":\"token from object\"}"
}
},
"model": {
"object_config": {
"fields": {
"token": {
"base_field": {
"type": "string",
"path": "token"
}
}
}
}
}
}
}
}Notifiers
Optional per-item config item.notifier_config which pushes the parse result somewhere after processing. The result is still returned as usual (CLI/MCP output, service logs); the notifier additionally delivers it. Works in Fitter (service mode), Fitter_CLI and Fitter_MCP.
type NotifierConfig struct {
Expression string `yaml:"expression" json:"expression"`
Force bool `json:"force" yaml:"force"`
SendArrayByItem bool `yaml:"send_array_by_item" json:"send_array_by_item"`
Template string `yaml:"template" json:"template"`
// exactly ONE destination:
Console *ConsoleConfig `yaml:"console" json:"console"`
TelegramBot *TelegramBotConfig `yaml:"telegram_bot" json:"telegram_bot"`
Http *HttpConfig `yaml:"http" json:"http"`
Redis *RedisNotifierConfig `json:"redis" yaml:"redis"`
File *FileStorageField `json:"file" yaml:"file"`
}Expression - optional expr-lang condition: notify only when it evaluates to true. The parse result is available as
fRes(parsed value),fResRaw(raw bytes),fResJson(JSON string), e.g.len(fResRaw) > 0Force - notify even if parsing finished with an error
SendArrayByItem - if the result is an array, send each element as a separate notification
Template - optional template applied to the result before sending, placeholders allowed
Destination - exactly one of
console,telegram_bot,http,redis,file
Destination configs:
type HttpConfig struct {
Url string `yaml:"url" json:"url"`
Method string `json:"method" yaml:"method"`
Headers map[string]string `yaml:"headers" json:"headers"`
Timeout uint32 `yaml:"timeout" json:"timeout"`
}
type TelegramBotConfig struct {
Token string `json:"token" yaml:"token"`
UsersId []int64 `json:"users_id" yaml:"users_id"`
Pretty bool `json:"pretty" yaml:"pretty"`
OnlyMsg bool `json:"only_msg" yaml:"only_msg"`
}
type RedisNotifierConfig struct {
Addr string `json:"addr" yaml:"addr"`
Password string `json:"password" yaml:"password"`
DB int `json:"db" yaml:"db"`
Channel string `json:"channel" yaml:"channel"`
}
type ConsoleConfig struct {
OnlyResult bool `json:"only_result" yaml:"only_result"`
}The file destination uses the same FileStorageField as the file field type.
Example (examples/config_telegram.json):
{
"item": {
"connector_config": { "...": "..." },
"model": { "...": "..." },
"notifier_config": {
"expression": "len(fResRaw) > 0",
"telegram_bot": {
"token": "{{{FromEnv=TG_TOKEN}}}",
"users_id": [123456],
"pretty": true
}
}
}
}Limits
Provide limitation for prevent DDOS, big usage of memory
type Limits struct {
HostRequestLimiter HostRequestLimiter `yaml:"host_request_limiter" json:"host_request_limiter"`
ChromiumInstance uint32 `yaml:"chromium_instance" json:"chromium_instance"`
DockerContainers uint32 `yaml:"docker_containers" json:"docker_containers"`
PlaywrightInstance uint32 `yaml:"playwright_instance" json:"playwright_instance"`
}HostRequestLimiter - map[string]int64 - limitation per host name, key is host, value is amount of parallel request(usage for server connector)
ChromiumInstance - amount of parallel chromium instance
DockerContainers - amount of parallel docker instance
PlaywrightInstance - amount of parallel playwright instance
https://github.com/PxyUp/fitter/blob/master/examples/cli/config_cli.json#L2
{
"limits": {
"host_request_limiter": {
"hacker-news.firebaseio.com": 5
},
"chromium_instance": 3,
"docker_containers": 3,
"playwright_instance": 3
}
}Maintenance
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