Add experimental "enable Pushpin" mode

Author: harmony7

CHANGELOG.md

@@ -5,6 +5,7 @@
 ### Breaking:
 
 ### Enhancements:
+- Add experimental "enable Pushpin" mode
 
 ### Bug fixes:
 

pkg/commands/compute/compute_test.go

@@ -101,8 +101,11 @@ func TestFlagDivergenceServe(t *testing.T) {
 	ignoreServeFlags := []string{
 		"addr",
 		"debug",
+		"experimental-enable-pushpin",
 		"file",
 		"profile-guest",
+		"pushpin-path",
+		"pushpin-port",
 		"profile-guest-dir",
 		"skip-build",
 		"viceroy-args",

pkg/commands/compute/serve.go

@@ -61,16 +61,19 @@ type ServeCommand struct {
 	ViceroyVersioner        github.AssetVersioner
 
 	// Serve private fields
-	addr            string
-	debug           bool
-	env             argparser.OptionalString
-	file            argparser.OptionalString
-	profileGuest    bool
-	profileGuestDir argparser.OptionalString
-	projectDir      string
-	skipBuild       bool
-	watch           bool
-	watchDir        argparser.OptionalString
+	addr                 string
+	debug                bool
+	enablePushpin        bool
+	pushpinRunnerBinPath string
+	pushpinProxyPort     string
+	env                  argparser.OptionalString
+	file                 argparser.OptionalString
+	profileGuest         bool
+	profileGuestDir      argparser.OptionalString
+	projectDir           string
+	skipBuild            bool
+	watch                bool
+	watchDir             argparser.OptionalString
 }
 
 // NewServeCommand returns a usable command registered under the parent.
@@ -92,6 +95,9 @@ func NewServeCommand(parent argparser.Registerer, g *global.Data, build *BuildCo
 	c.CmdClause.Flag("metadata-filter-envvars", "Redact specified environment variables from [scripts.env_vars] using comma-separated list").Action(c.metadataFilterEnvVars.Set).StringVar(&c.metadataFilterEnvVars.Value)
 	c.CmdClause.Flag("metadata-show", "Inspect the Wasm binary metadata").Action(c.metadataShow.Set).BoolVar(&c.metadataShow.Value)
 	c.CmdClause.Flag("package-name", "Package name").Action(c.packageName.Set).StringVar(&c.packageName.Value)
+	c.CmdClause.Flag("experimental-enable-pushpin", "Enable experimental Pushpin support for local testing of Fanout and WebSockets").BoolVar(&c.enablePushpin)
+	c.CmdClause.Flag("pushpin-path", "The path to a user installed version of the Pushpin runner binary").StringVar(&c.pushpinRunnerBinPath)
+	c.CmdClause.Flag("pushpin-port", "The port to run the Pushpin runner on. Defaults to 7677.").Default("7677").StringVar(&c.pushpinProxyPort)
 	c.CmdClause.Flag("profile-guest", "Profile the Wasm guest under Viceroy (requires Viceroy 0.9.1 or higher). View profiles at https://profiler.firefox.com/.").BoolVar(&c.profileGuest)
 	c.CmdClause.Flag("profile-guest-dir", "The directory where the per-request profiles are saved to. Defaults to guest-profiles.").Action(c.profileGuestDir.Set).StringVar(&c.profileGuestDir.Value)
 	c.CmdClause.Flag("skip-build", "Skip the build step").BoolVar(&c.skipBuild)
@@ -197,6 +203,51 @@ func (c *ServeCommand) Exec(in io.Reader, out io.Writer) (err error) {
 		return err
 	}
 
+	if c.enablePushpin {
+		pushpinRunnerBin, err := c.GetPushpinRunner(out)
+		if err != nil {
+			return err
+		}
+
+		var pushpinCmd *exec.Cmd
+		if pushpinRunnerBin != "" {
+			// The port should match what we tell Viceroy.
+			args := []string{"--port=" + c.pushpinProxyPort}
+
+			// Iterate backends and add them
+			routes := c.BuildPushpinRoutes()
+			args = append(args, routes...)
+
+			args = append(args, "--verbose")
+			pushpinCmd = exec.Command(pushpinRunnerBin, args...)
+
+			// If verbose, show the user what's happening and pipe Pushpin's output.
+			if c.Globals.Verbose() {
+				text.Info(out, "Starting Pushpin runner in the background...")
+				text.Output(out, "%s: %s", text.BoldYellow("Pushpin command"), strings.Join(pushpinCmd.Args, " "))
+				pushpinCmd.Stdout = out
+				pushpinCmd.Stderr = out
+			}
+
+			if err := pushpinCmd.Start(); err != nil {
+				return fmt.Errorf("failed to start Pushpin runner: %w", err)
+			}
+
+			// Ensure the Pushpin process is terminated when the serve command exits.
+			defer func() {
+				if pushpinCmd != nil && pushpinCmd.Process != nil {
+					if c.Globals.Verbose() {
+						text.Info(out, "Stopping Pushpin runner...")
+					}
+					// Attempt to kill the process. We don't block on waiting for it to exit.
+					if err := pushpinCmd.Process.Kill(); err != nil {
+						c.Globals.ErrLog.Add(fmt.Errorf("failed to kill Pushpin process: %w", err))
+					}
+				}
+			}()
+		}
+	}
+
 	err = spinner.Start()
 	if err != nil {
 		return err
@@ -217,20 +268,22 @@ func (c *ServeCommand) Exec(in io.Reader, out io.Writer) (err error) {
 	var restart bool
 	for {
 		err = local(localOpts{
-			addr:            c.addr,
-			bin:             bin,
-			debug:           c.debug,
-			errLog:          c.Globals.ErrLog,
-			extraArgs:       c.ViceroyBinExtraArgs,
-			manifestPath:    manifestPath,
-			out:             out,
-			profileGuest:    c.profileGuest,
-			profileGuestDir: c.profileGuestDir,
-			restarted:       restart,
-			verbose:         c.Globals.Verbose(),
-			wasmBinPath:     wasmBinaryToRun,
-			watch:           c.watch,
-			watchDir:        c.watchDir,
+			addr:             c.addr,
+			bin:              bin,
+			debug:            c.debug,
+			errLog:           c.Globals.ErrLog,
+			extraArgs:        c.ViceroyBinExtraArgs,
+			manifestPath:     manifestPath,
+			out:              out,
+			profileGuest:     c.profileGuest,
+			profileGuestDir:  c.profileGuestDir,
+			enablePushpin:    c.enablePushpin,
+			pushpinProxyPort: c.pushpinProxyPort,
+			restarted:        restart,
+			verbose:          c.Globals.Verbose(),
+			wasmBinPath:      wasmBinaryToRun,
+			watch:            c.watch,
+			watchDir:         c.watchDir,
 		})
 		if err != nil {
 			if err != fsterr.ErrViceroyRestart {
@@ -552,22 +605,105 @@ func (c *ServeCommand) InstallViceroy(
 	return spinner.Stop()
 }
 
+// GetPushpinRunner returns the path to the installed binary.
+//
+// This value comes from searching the system path for `pushpin`
+// It can be overridden by providing the --pushpin-path command-line parameter.
+func (c *ServeCommand) GetPushpinRunner(out io.Writer) (bin string, err error) {
+	if c.pushpinRunnerBinPath != "" {
+		if c.Globals.Verbose() {
+			text.Info(out, "Using user provided install of Pushpin runner via --pushpin-path flag: %s\n\n", c.pushpinRunnerBinPath)
+		}
+		return filepath.Abs(c.pushpinRunnerBinPath)
+	}
+
+	if c.Globals.Verbose() {
+		text.Info(out, "No --pushpin-path provided, attempting to find 'pushpin' in your PATH...")
+	}
+	path, err := exec.LookPath("pushpin")
+	if err != nil {
+		return "", fsterr.RemediationError{
+			Inner:       fmt.Errorf("failed to find 'pushpin' in your $PATH"),
+			Remediation: "Pushpin support was enabled via --enable-experimental-pushpin, but the 'pushpin' binary could not be found in your $PATH. Please install Pushpin (see: https://pushpin.org/docs/install/) or provide a path to the binary using the --pushpin-path flag.",
+		}
+	}
+
+	if c.Globals.Verbose() {
+		text.Info(out, "Found Pushpin runner via $PATH lookup: %s\n\n", path)
+	}
+	return filepath.Abs(path)
+}
+
+// BuildPushpinRoutes builds a slice of strings based on the backends
+// defined in the manifest's backend section.
+func (c *ServeCommand) BuildPushpinRoutes() []string {
+	var routes []string
+	for name, backend := range c.Globals.Manifest.File.LocalServer.Backends {
+
+		// e.g. a backend named "origin" will be mapped from "/origin".
+		pathPrefix := "/" + name
+
+		// The target should be a URL
+		u, err := url.Parse(backend.URL)
+		if err != nil {
+			// This is unlikely as we parse it elsewhere, but good to be safe.
+			// We'll just skip this backend if the URL is invalid.
+			continue
+		}
+
+		// A backend may have a path component. If it does, then
+		// it will be prepended during forwarding.
+		forwardPrefix := strings.TrimSuffix(u.Path, "/")
+
+		// Route Rule:
+		// 1. `*`: Match any Host header from the incoming request.
+		// 2. `path_beg`: Match requests whose path begins with the backend name prefix.
+		// 3. `replace_beg`: Replace the matched prefix with the forward prefix.
+		rules := fmt.Sprintf(
+			"*,path_beg=%s,replace_beg=%s",
+			pathPrefix,
+			forwardPrefix,
+		)
+		// 4. `as_host`: If the backend has an override_host.
+		if backend.OverrideHost != "" {
+			rules += fmt.Sprintf(",as_host=%s", backend.OverrideHost)
+		}
+
+		// Target:
+		// 1. `over_http`: Enable WebSocket-over-HTTP
+		target := u.Host + ",over_http"
+		// 2. `ssl`: If backend is https
+		if u.Scheme == "https" {
+			target += ",ssl"
+		}
+
+		// The final argument format is "--route=<rules> <target_url>"
+		routeArg := fmt.Sprintf("--route=%s %s", rules, target)
+		routes = append(routes, routeArg)
+
+	}
+
+	return routes
+}
+
 // localOpts represents the inputs for `local()`.
 type localOpts struct {
-	addr            string
-	bin             string
-	debug           bool
-	errLog          fsterr.LogInterface
-	extraArgs       string
-	manifestPath    string
-	out             io.Writer
-	profileGuest    bool
-	profileGuestDir argparser.OptionalString
-	restarted       bool
-	verbose         bool
-	wasmBinPath     string
-	watch           bool
-	watchDir        argparser.OptionalString
+	addr             string
+	bin              string
+	debug            bool
+	errLog           fsterr.LogInterface
+	extraArgs        string
+	manifestPath     string
+	out              io.Writer
+	profileGuest     bool
+	profileGuestDir  argparser.OptionalString
+	enablePushpin    bool
+	pushpinProxyPort string
+	restarted        bool
+	verbose          bool
+	wasmBinPath      string
+	watch            bool
+	watchDir         argparser.OptionalString
 }
 
 // local spawns a subprocess that runs the compiled binary.
@@ -592,6 +728,10 @@ func local(opts localOpts) error {
 		}
 	}
 
+	if opts.enablePushpin {
+		args = append(args, "--local-pushpin-proxy-port="+opts.pushpinProxyPort)
+	}
+
 	if opts.extraArgs != "" {
 		extraArgs := strings.Split(opts.extraArgs, " ")
 		args = append(args, extraArgs...)