Add k8ssandra demo support to CLI (#1367)

Summary: We want to add a K8ssandra demo to our list of demos. A few
changes needed to be made to ensure the demo can be deployed properly:
- We should check for cert-manager as a required dep. We decided not to
deploy this with the demo, since deploying 2 cert-managers can break
things. If we deploy cert-manager for the user, there's a bit of
bookkeeping we'd need to do if the user runs `px demo delete` to decide
whether or not we should also clean up cert-manager. Instead, we'll
leave this up to the user for the time-being.
- The demo deploys some CRDs. This can lead to race conditions if
deploying everything in the manifest at once. To handle this, added a
retry in the deploy block.

Relevant Issues: #680

Type of change: /kind cleanup

Test Plan: Push to dev demo manifest, `px demo deploy` with and without
cert-manager installed.

---------

Signed-off-by: Michelle Nguyen <michellenguyen@pixielabs.ai>

Author: aimichelle

demos/BUILD.bazel

@@ -45,11 +45,19 @@ pkg_tar(
     strip_prefix = "online-boutique",
 )
 
+pkg_tar(
+    name = "px-k8ssandra",
+    srcs = glob(["k8ssandra/*"]),
+    extension = "tar.gz",
+    strip_prefix = "k8ssandra",
+)
+
 ARCHIVES = [
     ":px-finagle",
     ":px-kafka",
     ":px-sock-shop",
     ":px-online-boutique",
+    ":px-k8ssandra",
 ]
 
 demo_upload(

demos/manifest.json

@@ -42,5 +42,12 @@
             "Mux tracing is only enabled on newer kernels (>= 5.2) by default.",
             "Make sure your system meets these requirements before deploying."
         ]
+    },
+    "px-k8ssandra": {
+        "description": "Microservice demo that spins up Cassandra and the Spring PetClinic demo app.",
+	"instructions": ["Use the px/cql_data script to view the Cassandra traffic flowing from the demo app."],
+	"dependencies": {
+            "cert-manager": true
+        }
     }
 }

src/pixie_cli/pkg/cmd/BUILD.bazel

@@ -66,6 +66,7 @@ go_library(
         "@com_github_alecthomas_chroma//quick",
         "@com_github_blang_semver//:semver",
         "@com_github_bmatcuk_doublestar//:doublestar",
+        "@com_github_cenkalti_backoff_v4//:backoff",
         "@com_github_dustin_go_humanize//:go-humanize",
         "@com_github_fatih_color//:color",
         "@com_github_gofrs_uuid//:uuid",

src/pixie_cli/pkg/cmd/demo.go

@@ -32,6 +32,7 @@ import (
 	"strings"
 	"time"
 
+	"github.com/cenkalti/backoff/v4"
 	"github.com/fatih/color"
 	"github.com/segmentio/analytics-go/v3"
 	log "github.com/sirupsen/logrus"
@@ -51,6 +52,7 @@ import (
 const manifestFile = "manifest.json"
 
 var errNamespaceAlreadyExists = errors.New("namespace already exists")
+var errCertMgrDoesNotExist = errors.New("cert-manager does not exist")
 
 func init() {
 	DemoCmd.PersistentFlags().String("artifacts", "https://storage.googleapis.com/pixie-prod-artifacts/prod-demo-apps", "The path to the demo apps")
@@ -324,11 +326,14 @@ func deployCmd(cmd *cobra.Command, args []string) {
 		return
 	}
 
-	err = setupDemoApp(appName, yamls)
+	err = setupDemoApp(appName, yamls, appSpec.Dependencies)
 	if err != nil {
 		if errors.Is(err, errNamespaceAlreadyExists) {
 			utils.Error("Failed to deploy demo application: namespace already exists.")
 			return
+		} else if errors.Is(err, errCertMgrDoesNotExist) {
+			utils.Error("Failed to deploy demo application: cert-manager needs to be installed. To deploy, please follow instructions at https://cert-manager.io/docs/getting-started/")
+			return
 		}
 		// Using log.Errorf rather than CLI log in order to track this unexpected error in Sentry.
 		log.WithError(err).Errorf("Error deploying demo application, deleting namespace %s", appName)
@@ -351,8 +356,9 @@ func deployCmd(cmd *cobra.Command, args []string) {
 }
 
 type manifestAppSpec struct {
-	Description  string   `json:"description"`
-	Instructions []string `json:"instructions"`
+	Description  string          `json:"description"`
+	Instructions []string        `json:"instructions"`
+	Dependencies map[string]bool `json:"dependencies"`
 }
 
 type manifest = map[string]*manifestAppSpec
@@ -468,9 +474,40 @@ func createNamespace(namespace string) error {
 	return err
 }
 
-func setupDemoApp(appName string, yamls map[string][]byte) error {
+func certManagerExists() (bool, error) {
 	kubeConfig := k8s.GetConfig()
 	clientset := k8s.GetClientset(kubeConfig)
+
+	deps, err := clientset.AppsV1().Deployments("").List(context.Background(), metav1.ListOptions{})
+	if err != nil {
+		return false, err
+	}
+
+	for _, d := range deps.Items {
+		if d.Name == "cert-manager" {
+			return true, nil
+		}
+	}
+
+	return false, err
+}
+
+func setupDemoApp(appName string, yamls map[string][]byte, deps map[string]bool) error {
+	kubeConfig := k8s.GetConfig()
+	clientset := k8s.GetClientset(kubeConfig)
+
+	// Check deps.
+	if deps["cert-manager"] {
+		certMgrExists, err := certManagerExists()
+		if err != nil && !k8s_errors.IsNotFound(err) {
+			return err
+		}
+
+		if !certMgrExists || k8s_errors.IsNotFound(err) {
+			return errCertMgrDoesNotExist
+		}
+	}
+
 	if namespaceExists(appName) {
 		fmt.Printf("%s: namespace %s already exists. If created with px, run %s to remove\n",
 			color.RedString("Error"), color.RedString(appName), color.GreenString(fmt.Sprintf("px demo delete %s", appName)))
@@ -484,7 +521,14 @@ func setupDemoApp(appName string, yamls map[string][]byte) error {
 		newTaskWrapper(fmt.Sprintf("Deploying %s YAMLs", appName), func() error {
 			for _, yamlBytes := range yamls {
 				yamlBytes := yamlBytes
-				err := k8s.ApplyYAML(clientset, kubeConfig, appName, bytes.NewReader(yamlBytes), false)
+				bo := backoff.NewExponentialBackOff()
+				bo.MaxElapsedTime = 5 * time.Minute
+
+				op := func() error {
+					return k8s.ApplyYAML(clientset, kubeConfig, appName, bytes.NewReader(yamlBytes), false)
+				}
+
+				err := backoff.Retry(op, bo)
 				if err != nil {
 					return err
 				}

src/utils/shared/k8s/apply.go

@@ -236,7 +236,7 @@ func ApplyResources(clientset kubernetes.Interface, config *rest.Config, resourc
 		nsRes := res.Namespace(objNS)
 
 		createRes := nsRes
-		if k8sRes == "namespaces" || k8sRes == "configmap" || k8sRes == "clusterrolebindings" || k8sRes == "clusterroles" || k8sRes == "customresourcedefinitions" {
+		if k8sRes == "validatingwebhookconfigurations" || k8sRes == "mutatingwebhookconfigurations" || k8sRes == "namespaces" || k8sRes == "configmap" || k8sRes == "clusterrolebindings" || k8sRes == "clusterroles" || k8sRes == "customresourcedefinitions" {
 			createRes = res
 		}