MCP Server: SSH Rails Runner

# MCP Server: SSH Rails Runner An MCP server that enables secure remote execution of Rails console commands via SSH. This server provides tools for both read-only operations and carefully managed mutations in a deployed Rails environment. This works great with Cursor. You can use Cursor Composer to pull in your Rails model files as context and then use the `execute_read_only`, `dry_run_mutate`, and `execute_mutate` tools to make changes to the database. No need to trudge through complicated Admin UI's to get your data wrangling and analysis done. ## Example  ## Features - Remote Rails console execution over SSH - Safe read-only operations - Dry-run capability for mutations - Execution of approved mutations - Resource management for code snippets ## Installation ```bash npm install npm run build ``` ## Configuration Set the following environment variables: ```bash SSH_HOST=your.remote.host SSH_USER=your_ssh_user SSH_PRIVATE_KEY_PATH=your_SSH_PRIVATE_KEY_PATH RAILS_WORKING_DIR=/path/to/rails/app ``` ## Usage with Claude Desktop Add to your Claude Desktop configuration: ```json { "mcpServers": { "ssh-rails-runner": { "command": "npx", "args": ["mcp-server-ssh-rails-runner"], "env": { "SSH_HOST": "your.remote.host", "SSH_USER": "your_ssh_user", "SSH_PRIVATE_KEY_PATH": "your_SSH_PRIVATE_KEY_PATH", "RAILS_WORKING_DIR": "/path/to/rails/app/root", "PROJECT_NAME_AS_CONTEXT": "Name that shows up in tool descriptions to help the LLM describe what kind of Rails project we're working with.", "CODE_SNIPPET_FILE_DIRECTORY": "/path/to/store/code/snippets/locally" } } } } ``` If `CODE_SNIPPET_FILE_DIRECTORY` is not provided, snippets will be stored in a temporary directory (e.g., `/tmp/mcp-ssh-rails-runner-code-snippets`). `PROJECT_NAME_AS_CONTEXT` is optional and helps identify the project context in tool descriptions. ## Available Tools The server now uses a Prepare -> Execute workflow: ### `mcp_ssh_rails_runner_prepare_code_snippet` - **Arguments**: `name` (string, for filename), `type` (enum: "readOnly" | "mutate"), `code` (string, Ruby code), `description` (string, optional). - **Function**: Saves the provided Ruby code to a local file named `code_snippet_<name>.json`, marks it as read-only or mutate, and opens the file for review. - **Returns**: The `file://` URI of the created snippet. ### `mcp_ssh_rails_runner_execute_code_snippet_read_only` - **Arguments**: `uri` (string, `file://` URI from `prepareCodeSnippet`). - **Function**: Reads the code snippet from the URI, verifies it's marked as `readOnly`, performs a safety check on the code, and executes it. - **Returns**: The output of the Rails command. ### `mcp_ssh_rails_runner_execute_code_snippet_mutate` - **Arguments**: `uri` (string, `file://` URI from `prepareCodeSnippet`). - **Function**: **DANGER ZONE!** Reads the code snippet, verifies it's marked as `mutate`, and **executes it directly**. There is no dry run or further safety check within this tool. - **Returns**: The output of the Rails command. - **Usage**: **ONLY CALL THIS AFTER THE USER HAS REVIEWED the prepared code (via the opened file from `prepareCodeSnippet`) AND EXPLICITLY CONFIRMED they want to execute the mutation.** ## Security Considerations - Only use with trusted SSH endpoints from your own local machine that is (temporarily) provided access to the remote environment. - **Crucially, always review the code saved by `prepareCodeSnippet` before executing any mutation with `executeCodeSnippetMutate`.** The responsibility for confirming mutations lies with the user and the calling AI. ## License MIT