cmd/gitops-pusher: port to use ffcli (#5113)

Signed-off-by: Xe <xe@tailscale.com>

cmd/gitops-pusher/gitops-pusher.go

@@ -20,39 +20,27 @@ import (
 	"strings"
 	"time"
 
+	"github.com/peterbourgon/ff/v3/ffcli"
 	"github.com/tailscale/hujson"
 )
 
 var (
-	policyFname  = flag.String("policy-file", "./policy.hujson", "filename for policy file")
+	rootFlagSet  = flag.NewFlagSet("gitops-pusher", flag.ExitOnError)
-	timeout      = flag.Duration("timeout", 5*time.Minute, "timeout for the entire CI run")
+	policyFname  = rootFlagSet.String("policy-file", "./policy.hujson", "filename for policy file")
-	githubSyntax = flag.Bool("github-syntax", true, "use GitHub Action error syntax (https://docs.github.com/en/actions/using-workflows/workflow-commands-for-github-actions#setting-an-error-message)")
+	timeout      = rootFlagSet.Duration("timeout", 5*time.Minute, "timeout for the entire CI run")
+	githubSyntax = rootFlagSet.Bool("github-syntax", true, "use GitHub Action error syntax (https://docs.github.com/en/actions/using-workflows/workflow-commands-for-github-actions#setting-an-error-message)")
 )
 
-func main() {
+func apply(tailnet, apiKey string) func(context.Context, []string) error {
-	flag.Parse()
+	return func(ctx context.Context, args []string) error {
-	ctx, cancel := context.WithTimeout(context.Background(), *timeout)
-	defer cancel()
-
-	tailnet, ok := os.LookupEnv("TS_TAILNET")
-	if !ok {
-		log.Fatal("set envvar TS_TAILNET to your tailnet's name")
-	}
-	apiKey, ok := os.LookupEnv("TS_API_KEY")
-	if !ok {
-		log.Fatal("set envvar TS_API_KEY to your Tailscale API key")
-	}
-
-	switch flag.Arg(0) {
-	case "apply":
 		controlEtag, err := getACLETag(ctx, tailnet, apiKey)
 		if err != nil {
-			log.Fatal(err)
+			return err
 		}
 
 		localEtag, err := sumFile(*policyFname)
 		if err != nil {
-			log.Fatal(err)
+			return err
 		}
 
 		log.Printf("control: %s", controlEtag)
@@ -60,23 +48,27 @@ func main() {
 
 		if controlEtag == localEtag {
 			log.Println("no update needed, doing nothing")
-			os.Exit(0)
+			return nil
 		}
 
 		if err := applyNewACL(ctx, tailnet, apiKey, *policyFname, controlEtag); err != nil {
-			fmt.Println(err)
+			return err
-			os.Exit(1)
+		}
+
+		return nil
+	}
 }
 
-	case "test":
+func test(tailnet, apiKey string) func(context.Context, []string) error {
+	return func(ctx context.Context, args []string) error {
 		controlEtag, err := getACLETag(ctx, tailnet, apiKey)
 		if err != nil {
-			log.Fatal(err)
+			return err
 		}
 
 		localEtag, err := sumFile(*policyFname)
 		if err != nil {
-			log.Fatal(err)
+			return err
 		}
 
 		log.Printf("control: %s", controlEtag)
@@ -84,16 +76,87 @@ func main() {
 
 		if controlEtag == localEtag {
 			log.Println("no updates found, doing nothing")
-			os.Exit(0)
+			return nil
 		}
 
 		if err := testNewACLs(ctx, tailnet, apiKey, *policyFname); err != nil {
+			return err
+		}
+		return nil
+	}
+}
+
+func getChecksums(tailnet, apiKey string) func(context.Context, []string) error {
+	return func(ctx context.Context, args []string) error {
+		controlEtag, err := getACLETag(ctx, tailnet, apiKey)
+		if err != nil {
+			return err
+		}
+
+		localEtag, err := sumFile(*policyFname)
+		if err != nil {
+			return err
+		}
+
+		log.Printf("control: %s", controlEtag)
+		log.Printf("local:   %s", localEtag)
+
+		return nil
+	}
+}
+
+func main() {
+	tailnet, ok := os.LookupEnv("TS_TAILNET")
+	if !ok {
+		log.Fatal("set envvar TS_TAILNET to your tailnet's name")
+	}
+	apiKey, ok := os.LookupEnv("TS_API_KEY")
+	if !ok {
+		log.Fatal("set envvar TS_API_KEY to your Tailscale API key")
+	}
+
+	applyCmd := &ffcli.Command{
+		Name:       "apply",
+		ShortUsage: "gitops-pusher [options] apply",
+		ShortHelp:  "Pushes changes to CONTROL",
+		LongHelp:   `Pushes changes to CONTROL`,
+		Exec:       apply(tailnet, apiKey),
+	}
+
+	testCmd := &ffcli.Command{
+		Name:       "test",
+		ShortUsage: "gitops-pusher [options] test",
+		ShortHelp:  "Tests ACL changes",
+		LongHelp:   "Tests ACL changes",
+		Exec:       test(tailnet, apiKey),
+	}
+
+	cksumCmd := &ffcli.Command{
+		Name:       "checksum",
+		ShortUsage: "Shows checksums of ACL files",
+		ShortHelp:  "Fetch checksum of CONTROL's ACL and the local ACL for comparison",
+		LongHelp:   "Fetch checksum of CONTROL's ACL and the local ACL for comparison",
+		Exec:       getChecksums(tailnet, apiKey),
+	}
+
+	root := &ffcli.Command{
+		ShortUsage:  "gitops-pusher [options] <command>",
+		ShortHelp:   "Push Tailscale ACLs to CONTROL using a GitOps workflow",
+		Subcommands: []*ffcli.Command{applyCmd, cksumCmd, testCmd},
+		FlagSet:     rootFlagSet,
+	}
+
+	if err := root.Parse(os.Args[1:]); err != nil {
+		log.Fatal(err)
+	}
+
+	ctx, cancel := context.WithTimeout(context.Background(), *timeout)
+	defer cancel()
+
+	if err := root.Run(ctx); err != nil {
 		fmt.Println(err)
 		os.Exit(1)
 	}
-	default:
-		log.Fatalf("usage: %s [options] <test|apply>", os.Args[0])
-	}
 }
 
 func sumFile(fname string) (string, error) {