Add option to format output as JSON/YAML

A new flag '-o' ('output') is introduced, allowing the user to choose the output format of the command. The options are json/yaml. The default behavior remains the same. The flag supports auto-completion for the output format options, implemented in the code of the command. To enable auto-completion when using the command as a plugin, an additional file 'kubectl_complete-cluster_compare' was added. The file should be present in a location in PATH along with the plugin to enable auto-completion. Also added supporting tests for JSON and YAML output modes.

Signed-off-by: Alina Sudakov <asudakov@redhat.com>

kubectl_complete-cluster_compare

@@ -0,0 +1,3 @@
+#!/usr/bin/env bash
+
+kubectl cluster-compare __complete "$@"

pkg/compare/compare.go

@@ -4,7 +4,9 @@ package compare
 
 import (
 	"bytes"
+	"encoding/json"
 	"fmt"
+	"io"
 	"io/fs"
 	"os"
 	"path/filepath"
@@ -27,6 +29,7 @@ import (
 	"k8s.io/kubectl/pkg/util/i18n"
 	"k8s.io/kubectl/pkg/util/templates"
 	"k8s.io/utils/exec"
+	"sigs.k8s.io/yaml"
 )
 
 var (
@@ -96,12 +99,20 @@ const (
 	DiffSeparator            = "**********************************"
 )
 
+const (
+	Json string = "json"
+	Yaml        = "yaml"
+)
+
+var OutputFormats = []string{Json, Yaml}
+
 type Options struct {
 	CRs                resource.FilenameOptions
 	templatesDir       string
 	diffConfigFileName string
 	diffAll            bool
 	ShowManagedFields  bool
+	OutputFormat       string
 
 	builder     *resource.Builder
 	corelator   *MetricsCorelatorDecorator
@@ -149,7 +160,6 @@ func NewCmd(f kcmdutil.Factory, streams genericiooptions.IOStreams) *cobra.Comma
 		kcmdutil.CheckDiffErr(kcmdutil.UsageErrorf(cmd, err.Error()))
 		return nil
 	})
-
 	cmd.Flags().IntVar(&options.Concurrency, "concurrency", 4,
 		"Number of objects to process in parallel when diffing against the live version. Larger number = faster,"+
 			" but more memory, I/O and CPU over that shorter period of time.")
@@ -161,6 +171,20 @@ func NewCmd(f kcmdutil.Factory, streams genericiooptions.IOStreams) *cobra.Comma
 		"If present, In live mode will try to match all resources that are from the types mentioned in the reference. "+
 			"In local mode will try to match all resources passed to the command")
 
+	cmd.Flags().StringVarP(&options.OutputFormat, "output", "o", "", fmt.Sprintf(`Output format. One of: (%s)`, strings.Join(OutputFormats, ", ")))
+	kcmdutil.CheckErr(cmd.RegisterFlagCompletionFunc(
+		"output",
+		func(cmd *cobra.Command, args []string, toComplete string) ([]string, cobra.ShellCompDirective) {
+			var comps []string
+			for _, format := range OutputFormats {
+				if strings.HasPrefix(format, toComplete) {
+					comps = append(comps, format)
+				}
+			}
+			return comps, cobra.ShellCompDirectiveNoFileComp
+		},
+	))
+
 	return cmd
 }
 
@@ -439,7 +463,11 @@ func (o *Options) Run() error {
 		return err
 	}
 	sum := newSummary(&o.reff, o.corelator, numDiffCRs)
-	o.Out.Write([]byte(Output{Summary: sum, Diffs: &diffs}.String()))
+
+	_, err = Output{Summary: sum, Diffs: &diffs}.Print(o.OutputFormat, o.Out)
+	if err != nil {
+		return err
+	}
 
 	// We will return exit code 1 in case there are differences between the reference CRs and cluster CRs.
 	//The differences can be differences found in specific CRs or the absence of CRs from the cluster.
@@ -487,9 +515,9 @@ func (obj InfoObject) Name() string {
 
 // DiffSum Contains the diff output and correlation info of a specific CR
 type DiffSum struct {
-	DiffOutput         string
-	CorrelatedTemplate string
-	CRName             string
+	DiffOutput         string `json:"DiffOutput"`
+	CorrelatedTemplate string `json:"CorrelatedTemplate"`
+	CRName             string `json:"CRName"`
 }
 
 func (s DiffSum) String() string {
@@ -509,10 +537,10 @@ Diff Output: None
 
 // Summary Contains all info included in the Summary output of the compare command
 type Summary struct {
-	RequiredCRS  map[string]map[string][]string
-	NumMissing   int
-	UnmatchedCRS []string
-	NumDiffCRs   int
+	RequiredCRS  map[string]map[string][]string `json:"RequiredCRS"`
+	NumMissing   int                            `json:"NumMissing"`
+	UnmatchedCRS []string                       `json:"UnmatchedCRS"`
+	NumDiffCRs   int                            `json:"NumDiffCRs"`
 }
 
 func newSummary(reference *Reference, c *MetricsCorelatorDecorator, numDiffCRs int) *Summary {
@@ -549,8 +577,8 @@ No CRs are unmatched to reference CRs
 
 // Output Contains the complete output of the command
 type Output struct {
-	Summary *Summary
-	Diffs   *[]DiffSum
+	Summary *Summary   `json:"Summary"`
+	Diffs   *[]DiffSum `json:"Diffs"`
 }
 
 func (o Output) String() string {
@@ -563,3 +591,22 @@ func (o Output) String() string {
 	}
 	return fmt.Sprintf("\n%s\n%s%s", DiffSeparator, str, o.Summary.String())
 }
+
+func (o Output) Print(format string, out io.Writer) (int, error) {
+	switch format {
+	case Json:
+		content, err := json.Marshal(o)
+		if err != nil {
+			return 0, err
+		}
+		return out.Write(append(content, []byte("\n")...))
+	case Yaml:
+		content, err := yaml.Marshal(o)
+		if err != nil {
+			return 0, err
+		}
+		return out.Write(content)
+	default:
+		return out.Write([]byte(o.String()))
+	}
+}

pkg/compare/compare_test.go

@@ -73,6 +73,7 @@ type Test struct {
 	mode                  []Mode
 	shouldPassUserConfig  bool
 	shouldDiffAll         bool
+	outputFormat          string
 }
 
 func (test *Test) getTestDir() string {
@@ -198,6 +199,16 @@ func TestCompareRun(t *testing.T) {
 			name: "Reff With Template Functions Renders As Expected",
 			mode: []Mode{{Live, LocalReff}, {Local, LocalReff}, {Local, URL}},
 		},
+		{
+			name:         "YAML Output",
+			mode:         []Mode{DefaultMode},
+			outputFormat: string(Yaml),
+		},
+		{
+			name:         "JSON Output",
+			mode:         []Mode{DefaultMode},
+			outputFormat: string(Json),
+		},
 	}
 	tf := cmdtesting.NewTestFactory()
 	testFlags := flag.NewFlagSet("test", flag.ContinueOnError)
@@ -230,7 +241,7 @@ func removeInconsistentInfo(t *testing.T, text string) []byte {
 	re := regexp.MustCompile("\\/tmp\\/(?:LIVE|MERGED)-[0-9]*")
 	text = re.ReplaceAllString(text, "TEMP")
 	//remove diff datetime
-	re = regexp.MustCompile("(\\d{4}-\\d{2}-\\d{2} \\d{2}:\\d{2}:\\d{2}\\.\\d{9} [+-]\\d{4})")
+	re = regexp.MustCompile("(\\d{4}-\\d{2}-\\d{2}\\s*\\d{2}:\\d{2}:\\d{2}\\.\\d{9} [+-]\\d{4})")
 	text = re.ReplaceAllString(text, "DATE")
 	pwd, err := os.Getwd()
 	require.NoError(t, err)
@@ -262,6 +273,9 @@ func getCommand(t *testing.T, test *Test, modeIndex int, tf *cmdtesting.TestFact
 	if test.shouldPassUserConfig {
 		require.NoError(t, cmd.Flags().Set("diff-config", path.Join(test.getTestDir(), userConfigFileName)))
 	}
+	if test.outputFormat != "" {
+		require.NoError(t, cmd.Flags().Set("output", test.outputFormat))
+	}
 	resourcesDir := path.Join(test.getTestDir(), resourceDirName)
 	switch mode.crSource {
 	case Local:

pkg/compare/testdata/JSONOutput/localerr.golden

@@ -0,0 +1,2 @@
+
+error code:1

pkg/compare/testdata/JSONOutput/localout.golden

@@ -0,0 +1 @@
+{"Summary":{"RequiredCRS":{"ExamplePart":{"Dashboard":["deploymentDashboard.yaml"]}},"NumMissing":1,"UnmatchedCRS":[],"NumDiffCRs":1},"Diffs":[{"DiffOutput":"diff -u -N TEMP/apps-v1_deployment_kubernetes-dashboard_dashboard-metrics-scraper TEMP/apps-v1_deployment_kubernetes-dashboard_dashboard-metrics-scraper\n--- TEMP/apps-v1_deployment_kubernetes-dashboard_dashboard-metrics-scraper\tDATE\n+++ TEMP/apps-v1_deployment_kubernetes-dashboard_dashboard-metrics-scraper\tDATE\n@@ -10,7 +10,7 @@\n   revisionHistoryLimit: 10\n   selector:\n     matchLabels:\n-      k8s-app: dashboard-metrics-scraper\n+      k8s-app: dashboard-metrics-scraper-diff\n   template:\n     metadata:\n       labels:\n","CorrelatedTemplate":"deploymentMetrics.yaml","CRName":"apps/v1_Deployment_kubernetes-dashboard_dashboard-metrics-scraper"}]}

pkg/compare/testdata/JSONOutput/reference/deploymentDashboard.yaml

@@ -0,0 +1,66 @@
+kind: Deployment
+apiVersion: apps/v1
+metadata:
+  labels:
+    k8s-app: kubernetes-dashboard
+  name: kubernetes-dashboard
+  namespace: kubernetes-dashboard
+spec:
+  replicas: 1
+  revisionHistoryLimit: 10
+  selector:
+    matchLabels:
+      k8s-app: kubernetes-dashboard
+  template:
+    metadata:
+      labels:
+        k8s-app: kubernetes-dashboard
+    spec:
+      securityContext:
+        seccompProfile:
+          type: RuntimeDefault
+      containers:
+        - name: kubernetes-dashboard
+          image: kubernetesui/dashboard:v2.7.0
+          imagePullPolicy: Always
+          ports:
+            - containerPort: 8443
+              protocol: TCP
+          args:
+            - --auto-generate-certificates
+            - --namespace=kubernetes-dashboard
+            # Uncomment the following line to manually specify Kubernetes API server Host
+            # If not specified, Dashboard will attempt to auto discover the API server and connect
+            # to it. Uncomment only if the default does not work.
+            # - --apiserver-host=http://my-address:port
+          volumeMounts:
+            - name: kubernetes-dashboard-certs
+              mountPath: /certs
+              # Create on-disk volume to store exec logs
+            - mountPath: /tmp
+              name: tmp-volume
+          livenessProbe:
+            httpGet:
+              scheme: HTTPS
+              path: /
+              port: 8443
+            initialDelaySeconds: 30
+            timeoutSeconds: 30
+          securityContext:
+            allowPrivilegeEscalation: false
+            readOnlyRootFilesystem: true
+            runAsUser: 1001
+            runAsGroup: 2001
+      volumes:
+        - name: kubernetes-dashboard-certs
+          secret:
+            secretName: kubernetes-dashboard-certs
+        - name: tmp-volume
+          emptyDir: { }
+      serviceAccountName: kubernetes-dashboard
+      nodeSelector:
+        "kubernetes.io/os": linux
+      # Comment the following tolerations if Dashboard must not be deployed on master
+      tolerations:
+        - key: node-role.kubernetes.io/master
+          effect: NoSchedule

pkg/compare/testdata/JSONOutput/reference/deploymentMetrics.yaml

@@ -0,0 +1,19 @@
+kind: Deployment
+apiVersion: apps/v1
+metadata:
+  labels:
+    k8s-app: dashboard-metrics-scraper
+  name: dashboard-metrics-scraper
+  namespace: kubernetes-dashboard
+spec:
+  replicas: 1
+  revisionHistoryLimit: 10
+  selector:
+    matchLabels:
+      k8s-app: dashboard-metrics-scraper
+  template:
+    metadata:
+      labels:
+        k8s-app: dashboard-metrics-scraper
+    spec:
+{{ if .spec.template.spec }}{{ .spec.template.spec | toYaml | indent 6 }}{{ end }}

pkg/compare/testdata/JSONOutput/reference/metadata.yaml

@@ -0,0 +1,8 @@
+Parts:
+  - name: ExamplePart
+    Components:
+      - name: Dashboard
+        type: Required
+        requiredTemplates:
+          - deploymentDashboard.yaml
+          - deploymentMetrics.yaml

pkg/compare/testdata/JSONOutput/resources/d2.yaml

@@ -0,0 +1,52 @@
+kind: Deployment
+apiVersion: apps/v1
+metadata:
+  labels:
+    k8s-app: dashboard-metrics-scraper
+  name: dashboard-metrics-scraper
+  namespace: kubernetes-dashboard
+spec:
+  replicas: 1
+  revisionHistoryLimit: 10
+  selector:
+    matchLabels:
+      k8s-app: dashboard-metrics-scraper-diff
+  template:
+    metadata:
+      labels:
+        k8s-app: dashboard-metrics-scraper
+    spec:
+      securityContext:
+        seccompProfile:
+          type: RuntimeDefault
+      containers:
+        - name: dashboard-metrics-scraper
+          image: kubernetesui/metrics-scraper:v1.0.8
+          ports:
+            - containerPort: 8000
+              protocol: TCP
+          livenessProbe:
+            httpGet:
+              scheme: HTTP
+              path: /
+              port: 8000
+            initialDelaySeconds: 30
+            timeoutSeconds: 30
+          volumeMounts:
+            - mountPath: /tmp
+              name: tmp-volume
+          securityContext:
+            allowPrivilegeEscalation: false
+            readOnlyRootFilesystem: true
+            runAsUser: 1001
+            runAsGroup: 2001
+      serviceAccountName: kubernetes-dashboard
+      nodeSelector:
+        "kubernetes.io/os": linux
+      # Comment the following tolerations if Dashboard must not be deployed on master
+      tolerations:
+        - key: node-role.kubernetes.io/master
+          effect: NoSchedule
+      volumes:
+        - name: tmp-volume
+          emptyDir: { }

pkg/compare/testdata/YAMLOutput/localerr.golden

@@ -0,0 +1,2 @@
+
+error code:1

pkg/compare/testdata/YAMLOutput/localout.golden

@@ -0,0 +1,16 @@
+Diffs:
+- CRName: apps/v1_Deployment_kubernetes-dashboard_kubernetes-dashboard
+  CorrelatedTemplate: deploymentDashboard.yaml
+  DiffOutput: "diff -u -N TEMP/apps-v1_deployment_kubernetes-dashboard_kubernetes-dashboard
+    TEMP/apps-v1_deployment_kubernetes-dashboard_kubernetes-dashboard\n---
+    TEMP/apps-v1_deployment_kubernetes-dashboard_kubernetes-dashboard\tDATE\n+++ TEMP/apps-v1_deployment_kubernetes-dashboard_kubernetes-dashboard\tDATE\n@@ -14,7 +14,7 @@\n   template:\n     metadata:\n       labels:\n-
+    \       k8s-app: kubernetes-dashboard\n+        k8s-app: kubernetes-dashboard-diff\n
+    \    spec:\n       containers:\n       - args:\n"
+Summary:
+  NumDiffCRs: 1
+  NumMissing: 1
+  RequiredCRS:
+    ExamplePart:
+      Dashboard:
+      - deploymentMetrics.yaml
+  UnmatchedCRS: []