Canary deployments for fission functions. (#892)

fission/util/util.go

@@ -23,6 +23,7 @@ import (
 	"regexp"
 	"strings"
 
+	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
 	"k8s.io/client-go/kubernetes"
 	restclient "k8s.io/client-go/rest"
 	"k8s.io/client-go/tools/clientcmd"
@@ -140,3 +141,25 @@ func GetKubernetesClient(kubeConfig string) (*restclient.Config, *kubernetes.Cli
 
 	return config, clientset
 }
+
+// given a list of functions, this checks if the functions actually exist on the cluster
+func CheckFunctionExistence(fissionClient *client.Client, functions []string, fnNamespace string) (err error) {
+	fnMissing := make([]string, 0)
+	for _, fnName := range functions {
+		meta := &metav1.ObjectMeta{
+			Name:      fnName,
+			Namespace: fnNamespace,
+		}
+
+		_, err := fissionClient.FunctionGet(meta)
+		if err != nil {
+			fnMissing = append(fnMissing, fnName)
+		}
+	}
+
+	if len(fnMissing) > 0 {
+		return fmt.Errorf("function(s) %s, not present in namespace : %s", fnMissing, fnNamespace)
+	}
+
+	return nil
+}