LogDog: Split CLI tool into package and main.

logdog/client/cli/main.go

Index: logdog/client/cli/main.go
diff --git a/logdog/client/cmd/logdog/main.go b/logdog/client/cli/main.go
similarity index 87%
copy from logdog/client/cmd/logdog/main.go
copy to logdog/client/cli/main.go
index 4ab743d21e14561cf168a6fcd3b1ab31a79f6302..2e9f7f07242038ab0f9d922239139dc1e036ea91 100644
--- a/logdog/client/cmd/logdog/main.go
+++ b/logdog/client/cli/main.go
@@ -2,7 +2,7 @@
 // Use of this source code is governed under the Apache License, Version 2.0
 // that can be found in the LICENSE file.
 
-package main
+package cli
 
 import (
 	"flag"
@@ -31,25 +31,37 @@ func init() {
 	prpc.DefaultUserAgent = "logdog CLI"
 }
 
+// Parameters is the set of application parametesr that can be supplied.
+type Parameters struct {
+	// Args is the command-line arguments. This should not include the command name,
+	// args[0].
+	Args []string
+
+	// Host is the default host name.
+	Host string
+}
+
 type application struct {
 	cli.Application
 	context.Context
 
+	// p is the set of runtime parameters to use.
+	p Parameters
+
 	// project is the project name. This may either be a valid project name or
 	// empty. Subcommands that support "unified" project-in-path paths should use
 	// splitPath to get the project form the path. Those that don't should assert
 	// that this is non-empty.
-	project     config.ProjectName
-	authFlags   authcli.Flags
-	coordinator string
-	insecure    bool
-	timeout     clockflag.Duration
+	project   config.ProjectName
+	authFlags authcli.Flags
+	insecure  bool
+	timeout   clockflag.Duration
 
 	coord *coordinator.Client
 }
 
 func (a *application) addToFlagSet(ctx context.Context, fs *flag.FlagSet) {
-	fs.StringVar(&a.coordinator, "host", "",
+	fs.StringVar(&a.p.Host, "host", a.p.Host,
 		"The LogDog Coordinator [host][:port].")
 	fs.BoolVar(&a.insecure, "insecure", false,
 		"Use insecure transport for RPC.")
@@ -94,8 +106,8 @@ func (a *application) timeoutCtx(c context.Context) (context.Context, context.Ca
 	return context.WithTimeout(c, time.Duration(a.timeout))
 }
 
-func mainImpl() int {
-	ctx := context.Background()
+// Main is the entry point for the CLI application.
+func Main(ctx context.Context, params Parameters) int {
 	ctx = gologger.StdConfig.Use(ctx)
 
 	authOptions := auth.Options{
@@ -119,6 +131,7 @@ func mainImpl() int {
 				authcli.SubcommandInfo(authOptions, "auth-info"),
 			},
 		},
+		p: params,
 	}
 	loggingConfig := log.Config{
 		Level: log.Level(log.Info),
@@ -130,7 +143,7 @@ func mainImpl() int {
 	a.authFlags.Register(flags, authOptions)
 
 	// Parse flags.
-	if err := flags.Parse(os.Args[1:]); err != nil {
+	if err := flags.Parse(params.Args); err != nil {
 		log.Errorf(log.SetError(ctx, err), "Failed to parse command-line.")
 		return 1
 	}
@@ -138,7 +151,7 @@ func mainImpl() int {
 	// Install our log formatter.
 	ctx = loggingConfig.Set(ctx)
 
-	if a.coordinator == "" {
+	if a.p.Host == "" {
 		log.Errorf(ctx, "Missing coordinator host (-host).")
 		return 1
 	}
@@ -181,7 +194,7 @@ func mainImpl() int {
 	// Get our Coordinator client instance.
 	prpcClient := &prpc.Client{
 		C:       httpClient,
-		Host:    a.coordinator,
+		Host:    a.p.Host,
 		Options: prpc.DefaultOptions(),
 	}
 	prpcClient.Options.Insecure = a.insecure
@@ -190,7 +203,3 @@ func mainImpl() int {
 	a.Context = ctx
 	return subcommands.Run(&a, flags.Args())
 }
-
-func main() {
-	os.Exit(mainImpl())
-}