Preflight check for a DNS pod (#289)

Signed-off-by: liz <liz@heptio.com>

cmd/sonobuoy/app/args.go

@@ -120,3 +120,11 @@ func AddRBACModeFlags(mode *RBACMode, cmd *cobra.Command, defaultMode RBACMode)
  `Whether to enable rbac on Sonobuoy. Options are "enable", "disable", and "detect" (query the server to see whether to enable Sonobuoy)`,
  )
 }
+
+// AddSkipPreflightFlag adds a boolean flag to skip preflight checks.
+func AddSkipPreflightFlag(flag *bool, cmd *cobra.Command) {
+ cmd.PersistentFlags().BoolVar(
+ flag, "preflight", false,
+ "If true, skip all checks before kicking off the sonobuoy run.",
+ )
+}

cmd/sonobuoy/app/run.go

@@ -51,6 +51,7 @@ func init() {
  AddKubeconfigFlag(&runFlags.kubecfg, cmd)
  // Default to detect since we need a kubeconfig regardless
  AddRBACModeFlags(&runFlags.rbacMode, cmd, DetectRBACMode)
+ AddSkipPreflightFlag(&runopts.SkipPreflight, cmd)
 
  RootCmd.AddCommand(cmd)
 }

pkg/client/interfaces.go

@@ -51,6 +51,8 @@ type E2EConfig struct {
 // RunConfig are the input options for running Sonobuoy.
 type RunConfig struct {
  GenConfig
+ // SkipPreflight means don't run any checks before kicking off the Sonobuoy run.
+ SkipPreflight bool
 }
 
 // RetrieveConfig are the options passed to RetrieveResults.

pkg/client/run.go

@@ -23,20 +23,31 @@ import (
  "github.com/pkg/errors"
  "github.com/sirupsen/logrus"
  "k8s.io/apimachinery/pkg/api/meta"
- "k8s.io/apimachinery/pkg/apis/meta/v1"
+ metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
  "k8s.io/apimachinery/pkg/apis/meta/v1/unstructured"
  "k8s.io/apimachinery/pkg/runtime"
  "k8s.io/apimachinery/pkg/runtime/schema"
  "k8s.io/apimachinery/pkg/util/yaml"
  "k8s.io/client-go/discovery"
  "k8s.io/client-go/dynamic"
+ "k8s.io/client-go/kubernetes"
  "k8s.io/client-go/kubernetes/scheme"
  "k8s.io/client-go/rest"
 )
 
 const bufferSize = 4096
 
 func (c *SonobuoyClient) Run(cfg *RunConfig, restConfig *rest.Config) error {
+ if !cfg.SkipPreflight {
+ client, err := kubernetes.NewForConfig(restConfig)
+ if err != nil {
+ return errors.Wrap(err, "couln't create Kubernetes client")
+ }
+ if err := preflightCheck(client); err != nil {
+ return errors.Wrap(err, "preflight check failed")
+ }
+ }
+
  manifest, err := c.GenerateManifest(&cfg.GenConfig)
  if err != nil {
  return errors.Wrap(err, "couldn't run invalid manifest")
@@ -99,7 +110,7 @@ func createObject(cfg *rest.Config, obj *unstructured.Unstructured, mapper meta.
  return errors.Wrap(err, "couldn't retrive object metadata")
  }
 
- _, err = client.Resource(&v1.APIResource{
+ _, err = client.Resource(&metav1.APIResource{
  Name: resource,
  Namespaced: namespace != "",
  }, namespace).Create(obj)
@@ -167,3 +178,26 @@ func unstructuredVersionInterface(version schema.GroupVersion) (*meta.VersionInt
  MetadataAccessor: meta.NewAccessor(),
  }, nil
 }
+
+const (
+ kubeSystemNamespace = "kube-system"
+ kubeDNSLabelKey = "k8s-app"
+ kubeDNSLabelValue = "kube-dns"
+)
+
+func preflightCheck(client kubernetes.Interface) error {
+ selector := metav1.AddLabelToSelector(&metav1.LabelSelector{}, kubeDNSLabelKey, kubeDNSLabelValue)
+
+ obj, err := client.CoreV1().Pods(kubeSystemNamespace).List(
+ metav1.ListOptions{LabelSelector: selector.String()},
+ )
+ if err != nil {
+ return errors.Wrap(err, "could not retrieve list of pods")
+ }
+
+ if len(obj.Items) == 0 {
+ return errors.New("no kube-dns tests found")
+ }
+
+ return nil
+}