extension: add jaeger dashboard sub-command (#5291)

This branch adds `jaeger dashboard` sub-command which is used
to view the jaeger dashboard. This follows the same logic/pattern
of that of `linkerd-dashboard`. Also, provides the same flags.

Signed-off-by: Tarun Pothulapati <tarunpothulapati@outlook.com>

jaeger/cmd/dashboard.go

@@ -0,0 +1,127 @@
+package cmd
+
+import (
+	"fmt"
+	"os"
+	"os/signal"
+	"time"
+
+	"github.com/linkerd/linkerd2/pkg/k8s"
+	"github.com/pkg/browser"
+	"github.com/spf13/cobra"
+)
+
+const (
+
+	// jaegerDeployment is the name of the jaeger deployment
+	jaegerDeployment = "jaeger"
+
+	// webPort is the http port of the jaeger deployment
+	webPort = 16686
+
+	// defaultHost is the default host used for port-forwarding via `jaeger dashboard`
+	defaultHost = "localhost"
+
+	// defaultPort is for port-forwarding via `jaeger dashboard`
+	defaultPort = 16686
+)
+
+// dashboardOptions holds values for command line flags that apply to the dashboard
+// command.
+type dashboardOptions struct {
+	host    string
+	port    int
+	showURL bool
+	wait    time.Duration
+}
+
+// newDashboardOptions initializes dashboard options with default
+// values for host, port. Also, set max wait time duration for
+// 300 seconds for the dashboard to become available
+//
+// These options may be overridden on the CLI at run-time
+func newDashboardOptions() *dashboardOptions {
+	return &dashboardOptions{
+		host: defaultHost,
+		port: defaultPort,
+		wait: 300 * time.Second,
+	}
+}
+
+// newCmdDashboard creates a new cobra command `dashboard` which contains commands for visualizing jaeger extension's dashboards.
+// After validating flag values, it will use the Kubernetes API to portforward requests to the Jaeger deployment
+// until the process gets killed/canceled
+func newCmdDashboard() *cobra.Command {
+	options := newDashboardOptions()
+
+	cmd := &cobra.Command{
+		Use:   "dashboard [flags]",
+		Short: "Open the Jaeger extension dashboard in a web browser",
+		Args:  cobra.NoArgs,
+		RunE: func(cmd *cobra.Command, args []string) error {
+			if options.port < 0 {
+				return fmt.Errorf("port must be greater than or equal to zero, was %d", options.port)
+			}
+
+			// TODO: Add a jaeger check here
+
+			k8sAPI, err := k8s.NewAPI(kubeconfigPath, kubeContext, impersonate, impersonateGroup, 0)
+			if err != nil {
+				return err
+			}
+
+			signals := make(chan os.Signal, 1)
+			signal.Notify(signals, os.Interrupt)
+			defer signal.Stop(signals)
+
+			portforward, err := k8s.NewPortForward(
+				cmd.Context(),
+				k8sAPI,
+				namespace,
+				jaegerDeployment,
+				options.host,
+				options.port,
+				webPort,
+				verbose,
+			)
+			if err != nil {
+				fmt.Fprintf(os.Stderr, "Failed to initialize port-forward: %s\n", err)
+				os.Exit(1)
+			}
+
+			if err = portforward.Init(); err != nil {
+				// TODO: consider falling back to an ephemeral port if defaultPort is taken
+				fmt.Fprintf(os.Stderr, "Error running port-forward: %s\nCheck for `jaeger dashboard` running in other terminal sessions, or use the `--port` flag.\n", err)
+				os.Exit(1)
+			}
+
+			go func() {
+				<-signals
+				portforward.Stop()
+			}()
+
+			webURL := portforward.URLFor("")
+
+			fmt.Printf("Jaeger extension dashboard available at:\n%s\n", webURL)
+
+			if !options.showURL {
+				err = browser.OpenURL(webURL)
+				if err != nil {
+					fmt.Fprintln(os.Stderr, "Failed to open dashboard automatically")
+					fmt.Fprintf(os.Stderr, "Visit %s in your browser to view the dashboard\n", webURL)
+				}
+			}
+
+			<-portforward.GetStop()
+			return nil
+		},
+	}
+
+	// This is identical to what `kubectl proxy --help` reports, `--port 0` indicates a random port.
+	cmd.PersistentFlags().StringVar(&options.host, "address", options.host, "The address at which to serve requests")
+	cmd.PersistentFlags().IntVarP(&options.port, "port", "p", options.port, "The local port on which to serve requests (when set to 0, a random port will be used)")
+	cmd.PersistentFlags().BoolVar(&options.showURL, "show-url", options.showURL, "show only URL in the CLI, and do not open the browser")
+	cmd.PersistentFlags().DurationVar(&options.wait, "wait", options.wait, "Wait for dashboard to become available if it's not available when the command is run")
+
+	return cmd
+}

jaeger/cmd/root.go

@@ -10,11 +10,13 @@ import (
 
 const (
 	defaultLinkerdNamespace = "linkerd"
+	defaultJaegerNamespace  = "linkerd-jaeger"
 )
 
 var (
 	apiAddr               string // An empty value means "use the Kubernetes configuration"
 	controlPlaneNamespace string
+	namespace             string
 	kubeconfigPath        string
 	kubeContext           string
 	impersonate           string
@@ -48,7 +50,8 @@ func NewCmdJaeger() *cobra.Command {
 		},
 	}
 
-	jaegerCmd.PersistentFlags().StringVarP(&controlPlaneNamespace, "linkerd-namespace", "L", defaultLinkerdNamespace, "Namespace in which Linkerd is installed [$LINKERD_NAMESPACE]")
+	jaegerCmd.PersistentFlags().StringVarP(&controlPlaneNamespace, "linkerd-namespace", "L", defaultLinkerdNamespace, "Namespace in which Linkerd is installed")
+	jaegerCmd.PersistentFlags().StringVarP(&namespace, "namespace", "n", defaultJaegerNamespace, "Namespace in which Jaeger extension is installed")
 	jaegerCmd.PersistentFlags().StringVar(&kubeconfigPath, "kubeconfig", "", "Path to the kubeconfig file to use for CLI requests")
 	jaegerCmd.PersistentFlags().StringVar(&kubeContext, "context", "", "Name of the kubeconfig context to use")
 	jaegerCmd.PersistentFlags().StringVar(&impersonate, "as", "", "Username to impersonate for Kubernetes operations")
@@ -56,6 +59,7 @@ func NewCmdJaeger() *cobra.Command {
 	jaegerCmd.PersistentFlags().StringVar(&apiAddr, "api-addr", "", "Override kubeconfig and communicate directly with the control plane at host:port (mostly for testing)")
 	jaegerCmd.PersistentFlags().BoolVar(&verbose, "verbose", false, "Turn on debug logging")
 	jaegerCmd.AddCommand(newCmdInstall())
+	jaegerCmd.AddCommand(newCmdDashboard())
 
 	return jaegerCmd
 }