google: Updating 3pi documentation

Fixing dead links in workload docs, adds workforce documentation

Change-Id: Ifad86e1937997f96ef577f5469d1e6fe496197b5
GitHub-Last-Rev: af28808
GitHub-Pull-Request: #638
Reviewed-on: https://go-review.googlesource.com/c/oauth2/+/478555
Auto-Submit: Cody Oss <codyoss@google.com>
Reviewed-by: Leo Siracusa <leosiracusa@google.com>
Reviewed-by: Cody Oss <codyoss@google.com>
Run-TryBot: Cody Oss <codyoss@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>

Author: aeitzman

google/doc.go

@@ -26,7 +26,7 @@
 //
 // Using workload identity federation, your application can access Google Cloud
 // resources from Amazon Web Services (AWS), Microsoft Azure or any identity
-// provider that supports OpenID Connect (OIDC).
+// provider that supports OpenID Connect (OIDC) or SAML 2.0.
 // Traditionally, applications running outside Google Cloud have used service
 // account keys to access Google Cloud resources. Using identity federation,
 // you can allow your workload to impersonate a service account.
@@ -36,26 +36,70 @@
 // Follow the detailed instructions on how to configure Workload Identity Federation
 // in various platforms:
 //
-//	Amazon Web Services (AWS): https://cloud.google.com/iam/docs/access-resources-aws
-//	Microsoft Azure: https://cloud.google.com/iam/docs/access-resources-azure
-//	OIDC identity provider: https://cloud.google.com/iam/docs/access-resources-oidc
+//	Amazon Web Services (AWS): https://cloud.google.com/iam/docs/workload-identity-federation-with-other-clouds#aws
+//	Microsoft Azure: https://cloud.google.com/iam/docs/workload-identity-federation-with-other-clouds#azure
+//	OIDC identity provider: https://cloud.google.com/iam/docs/workload-identity-federation-with-other-providers#oidc
+//	SAML 2.0 identity provider: https://cloud.google.com/iam/docs/workload-identity-federation-with-other-providers#saml
 //
 // For OIDC and SAML providers, the library can retrieve tokens in three ways:
 // from a local file location (file-sourced credentials), from a server
 // (URL-sourced credentials), or from a local executable (executable-sourced
 // credentials).
 // For file-sourced credentials, a background process needs to be continuously
-// refreshing the file location with a new OIDC token prior to expiration.
+// refreshing the file location with a new OIDC/SAML token prior to expiration.
 // For tokens with one hour lifetimes, the token needs to be updated in the file
 // every hour. The token can be stored directly as plain text or in JSON format.
 // For URL-sourced credentials, a local server needs to host a GET endpoint to
-// return the OIDC token. The response can be in plain text or JSON.
+// return the OIDC/SAML token. The response can be in plain text or JSON.
 // Additional required request headers can also be specified.
 // For executable-sourced credentials, an application needs to be available to
-// output the OIDC token and other information in a JSON format.
+// output the OIDC/SAML token and other information in a JSON format.
 // For more information on how these work (and how to implement
 // executable-sourced credentials), please check out:
-// https://cloud.google.com/iam/docs/using-workload-identity-federation#oidc
+// https://cloud.google.com/iam/docs/workload-identity-federation-with-other-providers#create_a_credential_configuration
+//
+// Note that this library does not perform any validation on the token_url, token_info_url,
+// or service_account_impersonation_url fields of the credential configuration.
+// It is not recommended to use a credential configuration that you did not generate with
+// the gcloud CLI unless you verify that the URL fields point to a googleapis.com domain.
+//
+// # Workforce Identity Federation
+//
+// Workforce identity federation lets you use an external identity provider (IdP) to
+// authenticate and authorize a workforce—a group of users, such as employees, partners,
+// and contractors—using IAM, so that the users can access Google Cloud services.
+// Workforce identity federation extends Google Cloud's identity capabilities to support
+// syncless, attribute-based single sign on.
+//
+// With workforce identity federation, your workforce can access Google Cloud resources
+// using an external identity provider (IdP) that supports OpenID Connect (OIDC) or
+// SAML 2.0 such as Azure Active Directory (Azure AD), Active Directory Federation
+// Services (AD FS), Okta, and others.
+//
+// Follow the detailed instructions on how to configure Workload Identity Federation
+// in various platforms:
+//
+//	Azure AD: https://cloud.google.com/iam/docs/workforce-sign-in-azure-ad
+//	Okta: https://cloud.google.com/iam/docs/workforce-sign-in-okta
+//	OIDC identity provider: https://cloud.google.com/iam/docs/configuring-workforce-identity-federation#oidc
+//	SAML 2.0 identity provider: https://cloud.google.com/iam/docs/configuring-workforce-identity-federation#saml
+//
+// For workforce identity federation, the library can retrieve tokens in three ways:
+// from a local file location (file-sourced credentials), from a server
+// (URL-sourced credentials), or from a local executable (executable-sourced
+// credentials).
+// For file-sourced credentials, a background process needs to be continuously
+// refreshing the file location with a new OIDC/SAML token prior to expiration.
+// For tokens with one hour lifetimes, the token needs to be updated in the file
+// every hour. The token can be stored directly as plain text or in JSON format.
+// For URL-sourced credentials, a local server needs to host a GET endpoint to
+// return the OIDC/SAML token. The response can be in plain text or JSON.
+// Additional required request headers can also be specified.
+// For executable-sourced credentials, an application needs to be available to
+// output the OIDC/SAML token and other information in a JSON format.
+// For more information on how these work (and how to implement
+// executable-sourced credentials), please check out:
+// https://cloud.google.com/iam/docs/workforce-obtaining-short-lived-credentials#generate_a_configuration_file_for_non-interactive_sign-in
 //
 // Note that this library does not perform any validation on the token_url, token_info_url,
 // or service_account_impersonation_url fields of the credential configuration.
@@ -86,5 +130,4 @@
 // same as the one obtained from the oauth2.Config returned from ConfigFromJSON or
 // JWTConfigFromJSON, but the Credentials may contain additional information
 // that is useful is some circumstances.
-//
 package google // import "golang.org/x/oauth2/google"