Issue #4: Fix - validate namespaces input by user via cmdline

* New function allNamespacesExist() checks for the existence of all the input namespaces in the k8s cluster
* Any namespace that is not found is logged to the user and the data collection aborted

Author: mrajagopal

cmd/nic-supportpkg.go

@@ -1,10 +1,12 @@
 package cmd
 
 import (
+	"context"
 	"fmt"
 	"github.com/nginxinc/nginx-k8s-supportpkg/pkg/data_collector"
 	"github.com/nginxinc/nginx-k8s-supportpkg/pkg/jobs"
 	"github.com/spf13/cobra"
+	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
 	"os"
 )
 
@@ -24,32 +26,55 @@ func Execute() {
 				os.Exit(1)
 			}
 
-			for _, job := range jobs.JobList() {
-				fmt.Printf("Running job %s...", job.Name)
-				err = job.Collect(collector)
+			if allNamespacesExist(collector) == true {
+
+				for _, job := range jobs.JobList() {
+					fmt.Printf("Running job %s...", job.Name)
+					err = job.Collect(collector)
+					if err != nil {
+						fmt.Printf(" Error: %s\n", err)
+					} else {
+						fmt.Print(" OK\n")
+					}
+				}
+
+				tarFile, err := collector.WrapUp()
 				if err != nil {
-					fmt.Printf(" Error: %s\n", err)
+					fmt.Println(fmt.Errorf("error when wrapping up: %s", err))
+					os.Exit(1)
 				} else {
-					fmt.Print(" OK\n")
+					fmt.Printf("Supportpkg successfully generated: %s\n", tarFile)
 				}
-			}
-
-			tarFile, err := collector.WrapUp()
-			if err != nil {
-				fmt.Println(fmt.Errorf("error when wrapping up: %s", err))
-				os.Exit(1)
 			} else {
-				fmt.Printf("Supportpkg successfully generated: %s\n", tarFile)
+				fmt.Println(" Error: all namespaces do not exist")
 			}
 		},
 	}
 
 	rootCmd.Flags().StringSliceVarP(&namespaces, "namespace", "n", []string{}, "list of namespaces to collect information from")
-	rootCmd.MarkFlagRequired("namespace")
+	if err := rootCmd.MarkFlagRequired("namespace"); err != nil {
+		fmt.Println(err)
+		os.Exit(1)
+	}
 	rootCmd.SetUsageTemplate("Usage: \n nic supportpkg [-n|--namespace] ns1 [-n|--namespace] ns2 ...\n nic supportpkg [-n|--namespace] ns1,ns2 ...\n")
 
 	if err := rootCmd.Execute(); err != nil {
 		fmt.Println(err)
 		os.Exit(1)
 	}
 }
+
+func allNamespacesExist(dc *data_collector.DataCollector) bool {
+
+	var allExist bool = true
+	for _, namespace := range dc.Namespaces {
+		_, err := dc.K8sCoreClientSet.CoreV1().Namespaces().Get(context.TODO(), namespace, metav1.GetOptions{})
+		if err != nil {
+			dc.Logger.Printf("\t%s: %v\n", namespace, err)
+			fmt.Printf("\t%s: %v\n", namespace, err)
+			allExist = false
+		}
+	}
+
+	return allExist
+}