google/default.go - oauth2 - Git at Google

 // Copyright 2015 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.

 package google

 import (
 	"context"
 	"encoding/json"
 	"fmt"
 	"net/http"
 	"os"
 	"path/filepath"
 	"runtime"
 	"time"

 	"cloud.google.com/go/compute/metadata"
 	"golang.org/x/oauth2"
 	"golang.org/x/oauth2/authhandler"
 )

 const (
 	adcSetupURL           = "https://cloud.google.com/docs/authentication/external/set-up-adc"
 	universeDomainDefault = "googleapis.com"
 )

 // Credentials holds Google credentials, including "Application Default Credentials".
 // For more details, see:
 // https://developers.google.com/accounts/docs/application-default-credentials
 // Credentials from external accounts (workload identity federation) are used to
 // identify a particular application from an on-prem or non-Google Cloud platform
 // including Amazon Web Services (AWS), Microsoft Azure or any identity provider
 // that supports OpenID Connect (OIDC).
 type Credentials struct {
 	ProjectID   string // may be empty
 	TokenSource oauth2.TokenSource

 	// JSON contains the raw bytes from a JSON credentials file.
 	// This field may be nil if authentication is provided by the
 	// environment and not with a credentials file, e.g. when code is
 	// running on Google Cloud Platform.
 	JSON []byte

 	// universeDomain is the default service domain for a given Cloud universe.
 	universeDomain string
 }

 // UniverseDomain returns the default service domain for a given Cloud universe.
 // The default value is "googleapis.com".
 func (c *Credentials) UniverseDomain() string {
 	if c.universeDomain == "" {
 		return universeDomainDefault
 	}
 	return c.universeDomain
 }

 // DefaultCredentials is the old name of Credentials.
 //
 // Deprecated: use Credentials instead.
 type DefaultCredentials = Credentials

 // CredentialsParams holds user supplied parameters that are used together
 // with a credentials file for building a Credentials object.
 type CredentialsParams struct {
 	// Scopes is the list OAuth scopes. Required.
 	// Example: https://www.googleapis.com/auth/cloud-platform
 	Scopes []string

 	// Subject is the user email used for domain wide delegation (see
 	// https://developers.google.com/identity/protocols/oauth2/service-account#delegatingauthority).
 	// Optional.
 	Subject string

 	// AuthHandler is the AuthorizationHandler used for 3-legged OAuth flow. Required for 3LO flow.
 	AuthHandler authhandler.AuthorizationHandler

 	// State is a unique string used with AuthHandler. Required for 3LO flow.
 	State string

 	// PKCE is used to support PKCE flow. Optional for 3LO flow.
 	PKCE *authhandler.PKCEParams

 	// The OAuth2 TokenURL default override. This value overrides the default TokenURL,
 	// unless explicitly specified by the credentials config file. Optional.
 	TokenURL string

 	// EarlyTokenRefresh is the amount of time before a token expires that a new
 	// token will be preemptively fetched. If unset the default value is 10
 	// seconds.
 	//
 	// Note: This option is currently only respected when using credentials
 	// fetched from the GCE metadata server.
 	EarlyTokenRefresh time.Duration
 }

 func (params CredentialsParams) deepCopy() CredentialsParams {
 	paramsCopy := params
 	paramsCopy.Scopes = make([]string, len(params.Scopes))
 	copy(paramsCopy.Scopes, params.Scopes)
 	return paramsCopy
 }

 // DefaultClient returns an HTTP Client that uses the
 // DefaultTokenSource to obtain authentication credentials.
 func DefaultClient(ctx context.Context, scope ...string) (*http.Client, error) {
 	ts, err := DefaultTokenSource(ctx, scope...)
 	if err != nil {
 		return nil, err
 	}
 	return oauth2.NewClient(ctx, ts), nil
 }

 // DefaultTokenSource returns the token source for
 // "Application Default Credentials".
 // It is a shortcut for FindDefaultCredentials(ctx, scope).TokenSource.
 func DefaultTokenSource(ctx context.Context, scope ...string) (oauth2.TokenSource, error) {
 	creds, err := FindDefaultCredentials(ctx, scope...)
 	if err != nil {
 		return nil, err
 	}
 	return creds.TokenSource, nil
 }

 // FindDefaultCredentialsWithParams searches for "Application Default Credentials".
 //
 // It looks for credentials in the following places,
 // preferring the first location found:
 //
 //  1. 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.
 //  2. 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.
 //  3. On Google App Engine standard first generation runtimes (<= Go 1.9) it uses
 //     the appengine.AccessToken function.
 //  4. On Google Compute Engine, Google App Engine standard second generation runtimes
 //     (>= Go 1.11), and Google App Engine flexible environment, it fetches
 //     credentials from the metadata server.
 func FindDefaultCredentialsWithParams(ctx context.Context, params CredentialsParams) (*Credentials, error) {
 	// Make defensive copy of the slices in params.
 	params = params.deepCopy()

 	// First, try the environment variable.
 	const envVar = "GOOGLE_APPLICATION_CREDENTIALS"
 	if filename := os.Getenv(envVar); filename != "" {
 		creds, err := readCredentialsFile(ctx, filename, params)
 		if err != nil {
 			return nil, fmt.Errorf("google: error getting credentials using %v environment variable: %v", envVar, err)
 		}
 		return creds, nil
 	}

 	// Second, try a well-known file.
 	filename := wellKnownFile()
 	if b, err := os.ReadFile(filename); err == nil {
 		return CredentialsFromJSONWithParams(ctx, b, params)
 	}

 	// Third, if we're on a Google App Engine standard first generation runtime (<= Go 1.9)
 	// use those credentials. App Engine standard second generation runtimes (>= Go 1.11)
 	// and App Engine flexible use ComputeTokenSource and the metadata server.
 	if appengineTokenFunc != nil {
 		return &Credentials{
 			ProjectID:   appengineAppIDFunc(ctx),
 			TokenSource: AppEngineTokenSource(ctx, params.Scopes...),
 		}, nil
 	}

 	// Fourth, if we're on Google Compute Engine, an App Engine standard second generation runtime,
 	// or App Engine flexible, use the metadata server.
 	if metadata.OnGCE() {
 		id, _ := metadata.ProjectID()
 		return &Credentials{
 			ProjectID:   id,
 			TokenSource: computeTokenSource("", params.EarlyTokenRefresh, params.Scopes...),
 		}, nil
 	}

 	// None are found; return helpful error.
 	return nil, fmt.Errorf("google: could not find default credentials. See %v for more information", adcSetupURL)
 }

 // FindDefaultCredentials invokes FindDefaultCredentialsWithParams with the specified scopes.
 func FindDefaultCredentials(ctx context.Context, scopes ...string) (*Credentials, error) {
 	var params CredentialsParams
 	params.Scopes = scopes
 	return FindDefaultCredentialsWithParams(ctx, params)
 }

 // CredentialsFromJSONWithParams obtains Google credentials from a JSON value. The JSON can
 // represent either a Google Developers Console client_credentials.json file (as in ConfigFromJSON),
 // a Google Developers service account key file, a gcloud user credentials file (a.k.a. refresh
 // token JSON), or the JSON configuration file for workload identity federation in non-Google cloud
 // platforms (see https://cloud.google.com/iam/docs/how-to#using-workload-identity-federation).
 func CredentialsFromJSONWithParams(ctx context.Context, jsonData []byte, params CredentialsParams) (*Credentials, error) {
 	// Make defensive copy of the slices in params.
 	params = params.deepCopy()

 	// First, attempt to parse jsonData as a Google Developers Console client_credentials.json.
 	config, _ := ConfigFromJSON(jsonData, params.Scopes...)
 	if config != nil {
 		return &Credentials{
 			ProjectID:   "",
 			TokenSource: authhandler.TokenSourceWithPKCE(ctx, config, params.State, params.AuthHandler, params.PKCE),
 			JSON:        jsonData,
 		}, nil
 	}

 	// Otherwise, parse jsonData as one of the other supported credentials files.
 	var f credentialsFile
 	if err := json.Unmarshal(jsonData, &f); err != nil {
 		return nil, err
 	}

 	ts, err := f.tokenSource(ctx, params)
 	if err != nil {
 		return nil, err
 	}
 	ts = newErrWrappingTokenSource(ts)
 	return &Credentials{
 		ProjectID:      f.ProjectID,
 		TokenSource:    ts,
 		JSON:           jsonData,
 		universeDomain: f.UniverseDomain,
 	}, nil
 }

 // CredentialsFromJSON invokes CredentialsFromJSONWithParams with the specified scopes.
 func CredentialsFromJSON(ctx context.Context, jsonData []byte, scopes ...string) (*Credentials, error) {
 	var params CredentialsParams
 	params.Scopes = scopes
 	return CredentialsFromJSONWithParams(ctx, jsonData, params)
 }

 func wellKnownFile() string {
 	const f = "application_default_credentials.json"
 	if runtime.GOOS == "windows" {
 		return filepath.Join(os.Getenv("APPDATA"), "gcloud", f)
 	}
 	return filepath.Join(guessUnixHomeDir(), ".config", "gcloud", f)
 }

 func readCredentialsFile(ctx context.Context, filename string, params CredentialsParams) (*Credentials, error) {
 	b, err := os.ReadFile(filename)
 	if err != nil {
 		return nil, err
 	}
 	return CredentialsFromJSONWithParams(ctx, b, params)
 }
	// Copyright 2015 The Go Authors. All rights reserved.
	// Use of this source code is governed by a BSD-style
	// license that can be found in the LICENSE file.

	package google

	import (
	"context"
	"encoding/json"
	"fmt"
	"net/http"
	"os"
	"path/filepath"
	"runtime"
	"time"

	"cloud.google.com/go/compute/metadata"
	"golang.org/x/oauth2"
	"golang.org/x/oauth2/authhandler"
	)

	const (
	adcSetupURL = "https://cloud.google.com/docs/authentication/external/set-up-adc"
	universeDomainDefault = "googleapis.com"
	)

	// Credentials holds Google credentials, including "Application Default Credentials".
	// For more details, see:
	// https://developers.google.com/accounts/docs/application-default-credentials
	// Credentials from external accounts (workload identity federation) are used to
	// identify a particular application from an on-prem or non-Google Cloud platform
	// including Amazon Web Services (AWS), Microsoft Azure or any identity provider
	// that supports OpenID Connect (OIDC).
	type Credentials struct {
	ProjectID string // may be empty
	TokenSource oauth2.TokenSource

	// JSON contains the raw bytes from a JSON credentials file.
	// This field may be nil if authentication is provided by the
	// environment and not with a credentials file, e.g. when code is
	// running on Google Cloud Platform.
	JSON []byte

	// universeDomain is the default service domain for a given Cloud universe.
	universeDomain string
	}

	// UniverseDomain returns the default service domain for a given Cloud universe.
	// The default value is "googleapis.com".
	func (c *Credentials) UniverseDomain() string {
	if c.universeDomain == "" {
	return universeDomainDefault
	}
	return c.universeDomain
	}

	// DefaultCredentials is the old name of Credentials.
	//
	// Deprecated: use Credentials instead.
	type DefaultCredentials = Credentials

	// CredentialsParams holds user supplied parameters that are used together
	// with a credentials file for building a Credentials object.
	type CredentialsParams struct {
	// Scopes is the list OAuth scopes. Required.
	// Example: https://www.googleapis.com/auth/cloud-platform
	Scopes []string

	// Subject is the user email used for domain wide delegation (see
	// https://developers.google.com/identity/protocols/oauth2/service-account#delegatingauthority).
	// Optional.
	Subject string

	// AuthHandler is the AuthorizationHandler used for 3-legged OAuth flow. Required for 3LO flow.
	AuthHandler authhandler.AuthorizationHandler

	// State is a unique string used with AuthHandler. Required for 3LO flow.
	State string

	// PKCE is used to support PKCE flow. Optional for 3LO flow.
	PKCE *authhandler.PKCEParams

	// The OAuth2 TokenURL default override. This value overrides the default TokenURL,
	// unless explicitly specified by the credentials config file. Optional.
	TokenURL string

	// EarlyTokenRefresh is the amount of time before a token expires that a new
	// token will be preemptively fetched. If unset the default value is 10
	// seconds.
	//
	// Note: This option is currently only respected when using credentials
	// fetched from the GCE metadata server.
	EarlyTokenRefresh time.Duration
	}

	func (params CredentialsParams) deepCopy() CredentialsParams {
	paramsCopy := params
	paramsCopy.Scopes = make([]string, len(params.Scopes))
	copy(paramsCopy.Scopes, params.Scopes)
	return paramsCopy
	}

	// DefaultClient returns an HTTP Client that uses the
	// DefaultTokenSource to obtain authentication credentials.
	func DefaultClient(ctx context.Context, scope ...string) (*http.Client, error) {
	ts, err := DefaultTokenSource(ctx, scope...)
	if err != nil {
	return nil, err
	}
	return oauth2.NewClient(ctx, ts), nil
	}

	// DefaultTokenSource returns the token source for
	// "Application Default Credentials".
	// It is a shortcut for FindDefaultCredentials(ctx, scope).TokenSource.
	func DefaultTokenSource(ctx context.Context, scope ...string) (oauth2.TokenSource, error) {
	creds, err := FindDefaultCredentials(ctx, scope...)
	if err != nil {
	return nil, err
	}
	return creds.TokenSource, nil
	}

	// FindDefaultCredentialsWithParams searches for "Application Default Credentials".
	//
	// It looks for credentials in the following places,
	// preferring the first location found:
	//
	// 1. 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.
	// 2. 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.
	// 3. On Google App Engine standard first generation runtimes (<= Go 1.9) it uses
	// the appengine.AccessToken function.
	// 4. On Google Compute Engine, Google App Engine standard second generation runtimes
	// (>= Go 1.11), and Google App Engine flexible environment, it fetches
	// credentials from the metadata server.
	func FindDefaultCredentialsWithParams(ctx context.Context, params CredentialsParams) (*Credentials, error) {
	// Make defensive copy of the slices in params.
	params = params.deepCopy()

	// First, try the environment variable.
	const envVar = "GOOGLE_APPLICATION_CREDENTIALS"
	if filename := os.Getenv(envVar); filename != "" {
	creds, err := readCredentialsFile(ctx, filename, params)
	if err != nil {
	return nil, fmt.Errorf("google: error getting credentials using %v environment variable: %v", envVar, err)
	}
	return creds, nil
	}

	// Second, try a well-known file.
	filename := wellKnownFile()
	if b, err := os.ReadFile(filename); err == nil {
	return CredentialsFromJSONWithParams(ctx, b, params)
	}

	// Third, if we're on a Google App Engine standard first generation runtime (<= Go 1.9)
	// use those credentials. App Engine standard second generation runtimes (>= Go 1.11)
	// and App Engine flexible use ComputeTokenSource and the metadata server.
	if appengineTokenFunc != nil {
	return &Credentials{
	ProjectID: appengineAppIDFunc(ctx),
	TokenSource: AppEngineTokenSource(ctx, params.Scopes...),
	}, nil
	}

	// Fourth, if we're on Google Compute Engine, an App Engine standard second generation runtime,
	// or App Engine flexible, use the metadata server.
	if metadata.OnGCE() {
	id, _ := metadata.ProjectID()
	return &Credentials{
	ProjectID: id,
	TokenSource: computeTokenSource("", params.EarlyTokenRefresh, params.Scopes...),
	}, nil
	}

	// None are found; return helpful error.
	return nil, fmt.Errorf("google: could not find default credentials. See %v for more information", adcSetupURL)
	}

	// FindDefaultCredentials invokes FindDefaultCredentialsWithParams with the specified scopes.
	func FindDefaultCredentials(ctx context.Context, scopes ...string) (*Credentials, error) {
	var params CredentialsParams
	params.Scopes = scopes
	return FindDefaultCredentialsWithParams(ctx, params)
	}

	// CredentialsFromJSONWithParams obtains Google credentials from a JSON value. The JSON can
	// represent either a Google Developers Console client_credentials.json file (as in ConfigFromJSON),
	// a Google Developers service account key file, a gcloud user credentials file (a.k.a. refresh
	// token JSON), or the JSON configuration file for workload identity federation in non-Google cloud
	// platforms (see https://cloud.google.com/iam/docs/how-to#using-workload-identity-federation).
	func CredentialsFromJSONWithParams(ctx context.Context, jsonData []byte, params CredentialsParams) (*Credentials, error) {
	// Make defensive copy of the slices in params.
	params = params.deepCopy()

	// First, attempt to parse jsonData as a Google Developers Console client_credentials.json.
	config, _ := ConfigFromJSON(jsonData, params.Scopes...)
	if config != nil {
	return &Credentials{
	ProjectID: "",
	TokenSource: authhandler.TokenSourceWithPKCE(ctx, config, params.State, params.AuthHandler, params.PKCE),
	JSON: jsonData,
	}, nil
	}

	// Otherwise, parse jsonData as one of the other supported credentials files.
	var f credentialsFile
	if err := json.Unmarshal(jsonData, &f); err != nil {
	return nil, err
	}

	ts, err := f.tokenSource(ctx, params)
	if err != nil {
	return nil, err
	}
	ts = newErrWrappingTokenSource(ts)
	return &Credentials{
	ProjectID: f.ProjectID,
	TokenSource: ts,
	JSON: jsonData,
	universeDomain: f.UniverseDomain,
	}, nil
	}

	// CredentialsFromJSON invokes CredentialsFromJSONWithParams with the specified scopes.
	func CredentialsFromJSON(ctx context.Context, jsonData []byte, scopes ...string) (*Credentials, error) {
	var params CredentialsParams
	params.Scopes = scopes
	return CredentialsFromJSONWithParams(ctx, jsonData, params)
	}

	func wellKnownFile() string {
	const f = "application_default_credentials.json"
	if runtime.GOOS == "windows" {
	return filepath.Join(os.Getenv("APPDATA"), "gcloud", f)
	}
	return filepath.Join(guessUnixHomeDir(), ".config", "gcloud", f)
	}

	func readCredentialsFile(ctx context.Context, filename string, params CredentialsParams) (*Credentials, error) {
	b, err := os.ReadFile(filename)
	if err != nil {
	return nil, err
	}
	return CredentialsFromJSONWithParams(ctx, b, params)
	}