detect.go•11.8 kB
// Copyright 2023 Google LLC
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
package credentials
import (
"context"
"encoding/json"
"errors"
"fmt"
"log/slog"
"net/http"
"os"
"time"
"cloud.google.com/go/auth"
"cloud.google.com/go/auth/internal"
"cloud.google.com/go/auth/internal/credsfile"
"cloud.google.com/go/compute/metadata"
"github.com/googleapis/gax-go/v2/internallog"
)
const (
// jwtTokenURL is Google's OAuth 2.0 token URL to use with the JWT(2LO) flow.
jwtTokenURL = "https://oauth2.googleapis.com/token"
// Google's OAuth 2.0 default endpoints.
googleAuthURL = "https://accounts.google.com/o/oauth2/auth"
googleTokenURL = "https://oauth2.googleapis.com/token"
// GoogleMTLSTokenURL is Google's default OAuth2.0 mTLS endpoint.
GoogleMTLSTokenURL = "https://oauth2.mtls.googleapis.com/token"
// Help on default credentials
adcSetupURL = "https://cloud.google.com/docs/authentication/external/set-up-adc"
)
var (
// for testing
allowOnGCECheck = true
)
// TokenBindingType specifies the type of binding used when requesting a token
// whether to request a hard-bound token using mTLS or an instance identity
// bound token using ALTS.
type TokenBindingType int
const (
// NoBinding specifies that requested tokens are not required to have a
// binding. This is the default option.
NoBinding TokenBindingType = iota
// MTLSHardBinding specifies that a hard-bound token should be requested
// using an mTLS with S2A channel.
MTLSHardBinding
// ALTSHardBinding specifies that an instance identity bound token should
// be requested using an ALTS channel.
ALTSHardBinding
)
// OnGCE reports whether this process is running in Google Cloud.
func OnGCE() bool {
// TODO(codyoss): once all libs use this auth lib move metadata check here
return allowOnGCECheck && metadata.OnGCE()
}
// DetectDefault searches for "Application Default Credentials" and returns
// a credential based on the [DetectOptions] provided.
//
// It looks for credentials in the following places, preferring the first
// location found:
//
// - A JSON file whose path is specified by the GOOGLE_APPLICATION_CREDENTIALS
// environment variable. For workload identity federation, refer to
// https://cloud.google.com/iam/docs/how-to#using-workload-identity-federation
// on how to generate the JSON configuration file for on-prem/non-Google
// cloud platforms.
// - A JSON file in a location known to the gcloud command-line tool. On
// Windows, this is %APPDATA%/gcloud/application_default_credentials.json. On
// other systems, $HOME/.config/gcloud/application_default_credentials.json.
// - On Google Compute Engine, Google App Engine standard second generation
// runtimes, and Google App Engine flexible environment, it fetches
// credentials from the metadata server.
func DetectDefault(opts *DetectOptions) (*auth.Credentials, error) {
if err := opts.validate(); err != nil {
return nil, err
}
if len(opts.CredentialsJSON) > 0 {
return readCredentialsFileJSON(opts.CredentialsJSON, opts)
}
if opts.CredentialsFile != "" {
return readCredentialsFile(opts.CredentialsFile, opts)
}
if filename := os.Getenv(credsfile.GoogleAppCredsEnvVar); filename != "" {
creds, err := readCredentialsFile(filename, opts)
if err != nil {
return nil, err
}
return creds, nil
}
fileName := credsfile.GetWellKnownFileName()
if b, err := os.ReadFile(fileName); err == nil {
return readCredentialsFileJSON(b, opts)
}
if OnGCE() {
metadataClient := metadata.NewWithOptions(&metadata.Options{
Logger: opts.logger(),
UseDefaultClient: true,
})
return auth.NewCredentials(&auth.CredentialsOptions{
TokenProvider: computeTokenProvider(opts, metadataClient),
ProjectIDProvider: auth.CredentialsPropertyFunc(func(ctx context.Context) (string, error) {
return metadataClient.ProjectIDWithContext(ctx)
}),
UniverseDomainProvider: &internal.ComputeUniverseDomainProvider{
MetadataClient: metadataClient,
},
}), nil
}
return nil, fmt.Errorf("credentials: could not find default credentials. See %v for more information", adcSetupURL)
}
// DetectOptions provides configuration for [DetectDefault].
type DetectOptions struct {
// Scopes that credentials tokens should have. Example:
// https://www.googleapis.com/auth/cloud-platform. Required if Audience is
// not provided.
Scopes []string
// TokenBindingType specifies the type of binding used when requesting a
// token whether to request a hard-bound token using mTLS or an instance
// identity bound token using ALTS. Optional.
TokenBindingType TokenBindingType
// Audience that credentials tokens should have. Only applicable for 2LO
// flows with service accounts. If specified, scopes should not be provided.
Audience string
// Subject is the user email used for [domain wide delegation](https://developers.google.com/identity/protocols/oauth2/service-account#delegatingauthority).
// Optional.
Subject string
// EarlyTokenRefresh configures how early before a token expires that it
// should be refreshed. Once the token’s time until expiration has entered
// this refresh window the token is considered valid but stale. If unset,
// the default value is 3 minutes and 45 seconds. Optional.
EarlyTokenRefresh time.Duration
// DisableAsyncRefresh configures a synchronous workflow that refreshes
// stale tokens while blocking. The default is false. Optional.
DisableAsyncRefresh bool
// AuthHandlerOptions configures an authorization handler and other options
// for 3LO flows. It is required, and only used, for client credential
// flows.
AuthHandlerOptions *auth.AuthorizationHandlerOptions
// TokenURL allows to set the token endpoint for user credential flows. If
// unset the default value is: https://oauth2.googleapis.com/token.
// Optional.
TokenURL string
// STSAudience is the audience sent to when retrieving an STS token.
// Currently this only used for GDCH auth flow, for which it is required.
STSAudience string
// CredentialsFile overrides detection logic and sources a credential file
// from the provided filepath. If provided, CredentialsJSON must not be.
// Optional.
//
// Important: If you accept a credential configuration (credential
// JSON/File/Stream) from an external source for authentication to Google
// Cloud Platform, you must validate it before providing it to any Google
// API or library. Providing an unvalidated credential configuration to
// Google APIs can compromise the security of your systems and data. For
// more information, refer to [Validate credential configurations from
// external sources](https://cloud.google.com/docs/authentication/external/externally-sourced-credentials).
CredentialsFile string
// CredentialsJSON overrides detection logic and uses the JSON bytes as the
// source for the credential. If provided, CredentialsFile must not be.
// Optional.
//
// Important: If you accept a credential configuration (credential
// JSON/File/Stream) from an external source for authentication to Google
// Cloud Platform, you must validate it before providing it to any Google
// API or library. Providing an unvalidated credential configuration to
// Google APIs can compromise the security of your systems and data. For
// more information, refer to [Validate credential configurations from
// external sources](https://cloud.google.com/docs/authentication/external/externally-sourced-credentials).
CredentialsJSON []byte
// UseSelfSignedJWT directs service account based credentials to create a
// self-signed JWT with the private key found in the file, skipping any
// network requests that would normally be made. Optional.
UseSelfSignedJWT bool
// Client configures the underlying client used to make network requests
// when fetching tokens. Optional.
Client *http.Client
// UniverseDomain is the default service domain for a given Cloud universe.
// The default value is "googleapis.com". This option is ignored for
// authentication flows that do not support universe domain. Optional.
UniverseDomain string
// Logger is used for debug logging. If provided, logging will be enabled
// at the loggers configured level. By default logging is disabled unless
// enabled by setting GOOGLE_SDK_GO_LOGGING_LEVEL in which case a default
// logger will be used. Optional.
Logger *slog.Logger
}
func (o *DetectOptions) validate() error {
if o == nil {
return errors.New("credentials: options must be provided")
}
if len(o.Scopes) > 0 && o.Audience != "" {
return errors.New("credentials: both scopes and audience were provided")
}
if len(o.CredentialsJSON) > 0 && o.CredentialsFile != "" {
return errors.New("credentials: both credentials file and JSON were provided")
}
return nil
}
func (o *DetectOptions) tokenURL() string {
if o.TokenURL != "" {
return o.TokenURL
}
return googleTokenURL
}
func (o *DetectOptions) scopes() []string {
scopes := make([]string, len(o.Scopes))
copy(scopes, o.Scopes)
return scopes
}
func (o *DetectOptions) client() *http.Client {
if o.Client != nil {
return o.Client
}
return internal.DefaultClient()
}
func (o *DetectOptions) logger() *slog.Logger {
return internallog.New(o.Logger)
}
func readCredentialsFile(filename string, opts *DetectOptions) (*auth.Credentials, error) {
b, err := os.ReadFile(filename)
if err != nil {
return nil, err
}
return readCredentialsFileJSON(b, opts)
}
func readCredentialsFileJSON(b []byte, opts *DetectOptions) (*auth.Credentials, error) {
// attempt to parse jsonData as a Google Developers Console client_credentials.json.
config := clientCredConfigFromJSON(b, opts)
if config != nil {
if config.AuthHandlerOpts == nil {
return nil, errors.New("credentials: auth handler must be specified for this credential filetype")
}
tp, err := auth.New3LOTokenProvider(config)
if err != nil {
return nil, err
}
return auth.NewCredentials(&auth.CredentialsOptions{
TokenProvider: tp,
JSON: b,
}), nil
}
return fileCredentials(b, opts)
}
func clientCredConfigFromJSON(b []byte, opts *DetectOptions) *auth.Options3LO {
var creds credsfile.ClientCredentialsFile
var c *credsfile.Config3LO
if err := json.Unmarshal(b, &creds); err != nil {
return nil
}
switch {
case creds.Web != nil:
c = creds.Web
case creds.Installed != nil:
c = creds.Installed
default:
return nil
}
if len(c.RedirectURIs) < 1 {
return nil
}
var handleOpts *auth.AuthorizationHandlerOptions
if opts.AuthHandlerOptions != nil {
handleOpts = &auth.AuthorizationHandlerOptions{
Handler: opts.AuthHandlerOptions.Handler,
State: opts.AuthHandlerOptions.State,
PKCEOpts: opts.AuthHandlerOptions.PKCEOpts,
}
}
return &auth.Options3LO{
ClientID: c.ClientID,
ClientSecret: c.ClientSecret,
RedirectURL: c.RedirectURIs[0],
Scopes: opts.scopes(),
AuthURL: c.AuthURI,
TokenURL: c.TokenURI,
Client: opts.client(),
Logger: opts.logger(),
EarlyTokenExpiry: opts.EarlyTokenRefresh,
AuthHandlerOpts: handleOpts,
// TODO(codyoss): refactor this out. We need to add in auto-detection
// for this use case.
AuthStyle: auth.StyleInParams,
}
}