Extend LUCI_CONTEXT["local_auth"] protocol to understand accounts.

client/authcli/authcli.go

 // Copyright 2015 The LUCI Authors. All rights reserved.
 // Use of this source code is governed under the Apache License, Version 2.0
 // that can be found in the LICENSE file.
 
 // Package authcli implements authentication related flags parsing and CLI
 // subcommands.
 //
 // It can be used from CLI tools that want customize authentication
 // configuration from the command line.
 //
@@ skipping 485 matching lines @@
         } else {
                 // An authenticator preconfigured with given list of scopes.
                 logging.Debugf(ctx, "Using rigid token generator: %s (scopes %s)", opts.Method, opts.Scopes)
                 gen, err = localauth.NewRigidGenerator(ctx, authenticator)
         }
         if err != nil {
                 fmt.Fprintln(os.Stderr, err)
                 return ExitCodeNoValidToken
         }
 
+        // We currently always setup a context with one account (which is also
+        // default). To avoid confusion where it comes from, we name it 'authutil'.
+        // Most tools should not care how it is named, as long as it is specified as
+        // 'default_account_id' in LUCI_CONTEXT["local_auth"].
+        srv := &localauth.Server{
+                TokenGenerators: map[string]localauth.TokenGenerator{
+                        "authutil": gen,
+                },
+                DefaultAccountID: "authutil",
+        }
+
         // Enter the environment with the local auth server.
-        srv := &localauth.Server{TokenGenerator: gen}
         err = localauth.WithLocalAuth(ctx, srv, func(ctx context.Context) error {
                 // Put the new LUCI_CONTEXT file, prepare cmd environ.
                 exported, err := lucictx.Export(ctx, "")
                 if err != nil {
                         logging.WithError(err).Errorf(ctx, "Failed to prepare LUCI_CONTEXT file")
                         return err
                 }
                 defer func() {
                         if err := exported.Close(); err != nil {
                                 logging.WithError(err).Warningf(ctx, "Failed to remove LUCI_CONTEXT file")
@@ skipping 50 matching lines @@
         }
         fmt.Printf("OAuth token details:\n")
         fmt.Printf("  Client ID: %s\n", info.Aud)
         fmt.Printf("  Scopes:\n")
         for _, scope := range strings.Split(info.Scope, " ") {
                 fmt.Printf("    %s\n", scope)
         }
 
         return ExitCodeSuccess
 }