Replace kubectl with Go server-side apply

Signed-off-by: Stefan Prodan <stefan.prodan@gmail.com>

cmd/flux/check.go

@@ -18,9 +18,7 @@ package main
 
 import (
 	"context"
-	"encoding/json"
 	"os"
-	"os/exec"
 	"time"
 
 	"github.com/Masterminds/semver/v3"
@@ -73,18 +71,11 @@ func init() {
 }
 
 func runCheckCmd(cmd *cobra.Command, args []string) error {
-	ctx, cancel := context.WithTimeout(context.Background(), rootArgs.timeout)
-	defer cancel()
-
 	logger.Actionf("checking prerequisites")
 	checkFailed := false
 
 	fluxCheck()
 
-	if !kubectlCheck(ctx, ">=1.18.0-0") {
-		checkFailed = true
-	}
-
 	if !kubernetesCheck(">=1.16.0-0") {
 		checkFailed = true
 	}
@@ -130,42 +121,6 @@ func fluxCheck() {
 	}
 }
 
-func kubectlCheck(ctx context.Context, constraint string) bool {
-	_, err := exec.LookPath("kubectl")
-	if err != nil {
-		logger.Failuref("kubectl not found")
-		return false
-	}
-
-	kubectlArgs := []string{"version", "--client", "--output", "json"}
-	output, err := utils.ExecKubectlCommand(ctx, utils.ModeCapture, rootArgs.kubeconfig, rootArgs.kubecontext, kubectlArgs...)
-	if err != nil {
-		logger.Failuref("kubectl version can't be determined")
-		return false
-	}
-
-	kv := &kubectlVersion{}
-	if err = json.Unmarshal([]byte(output), kv); err != nil {
-		logger.Failuref("kubectl version output can't be unmarshalled")
-		return false
-	}
-
-	v, err := version.ParseVersion(kv.ClientVersion.GitVersion)
-	if err != nil {
-		logger.Failuref("kubectl version can't be parsed")
-		return false
-	}
-
-	c, _ := semver.NewConstraint(constraint)
-	if !c.Check(v) {
-		logger.Failuref("kubectl version %s < %s", v.Original(), constraint)
-		return false
-	}
-
-	logger.Successf("kubectl %s %s", v.String(), constraint)
-	return true
-}
-
 func kubernetesCheck(constraint string) bool {
 	cfg, err := utils.KubeConfig(rootArgs.kubeconfig, rootArgs.kubecontext)
 	if err != nil {

cmd/flux/check_test.go

@@ -23,13 +23,11 @@ func TestCheckPre(t *testing.T) {
 		t.Fatalf("Error unmarshalling: %v", err.Error())
 	}
 
-	clientVersion := strings.TrimPrefix(versions["clientVersion"].GitVersion, "v")
 	serverVersion := strings.TrimPrefix(versions["serverVersion"].GitVersion, "v")
 
 	cmd := cmdTestCase{
 		args: "check --pre",
 		assert: assertGoldenTemplateFile("testdata/check/check_pre.golden", map[string]string{
-			"clientVersion": clientVersion,
 			"serverVersion": serverVersion,
 		}),
 	}

cmd/flux/install.go

@@ -41,13 +41,13 @@ If a previous version is installed, then an in-place upgrade will be performed.`
   flux install --version=latest --namespace=flux-system
 
   # Install a specific version and a series of components
-  flux install --dry-run --version=v0.0.7 --components="source-controller,kustomize-controller"
+  flux install --version=v0.0.7 --components="source-controller,kustomize-controller"
 
   # Install Flux onto tainted Kubernetes nodes
   flux install --toleration-keys=node.kubernetes.io/dedicated-to-flux
 
-  # Dry-run install with manifests preview
-  flux install --dry-run --verbose
+  # Dry-run install
+  flux install --export | kubectl apply --dry-run=client -f- 
 
   # Write install manifests to file
   flux install --export > flux-system.yaml`,
@@ -102,6 +102,7 @@ func init() {
 		"list of toleration keys used to schedule the components pods onto nodes with matching taints")
 	installCmd.Flags().MarkHidden("manifests")
 	installCmd.Flags().MarkDeprecated("arch", "multi-arch container image is now available for AMD64, ARMv7 and ARM64")
+	installCmd.Flags().MarkDeprecated("dry-run", "use 'flux install --export | kubectl apply --dry-run=client -f-'")
 	rootCmd.AddCommand(installCmd)
 }
 
@@ -188,25 +189,19 @@ func installCmdRun(cmd *cobra.Command, args []string) error {
 
 	logger.Successf("manifests build completed")
 	logger.Actionf("installing components in %s namespace", rootArgs.namespace)
-	applyOutput := utils.ModeStderrOS
-	if rootArgs.verbose {
-		applyOutput = utils.ModeOS
-	}
-
-	kubectlArgs := []string{"apply", "-f", filepath.Join(tmpDir, manifest.Path)}
-	if installArgs.dryRun {
-		kubectlArgs = append(kubectlArgs, "--dry-run=client")
-		applyOutput = utils.ModeOS
-	}
-	if _, err := utils.ExecKubectlCommand(ctx, applyOutput, rootArgs.kubeconfig, rootArgs.kubecontext, kubectlArgs...); err != nil {
-		return fmt.Errorf("install failed: %w", err)
-	}
 
 	if installArgs.dryRun {
 		logger.Successf("install dry-run finished")
 		return nil
 	}
 
+	applyOutput, err := utils.Apply(ctx, rootArgs.kubeconfig, rootArgs.kubecontext, filepath.Join(tmpDir, manifest.Path))
+	if err != nil {
+		return fmt.Errorf("install failed: %w", err)
+	}
+
+	fmt.Fprintln(os.Stderr, applyOutput)
+
 	kubeConfig, err := utils.KubeConfig(rootArgs.kubeconfig, rootArgs.kubecontext)
 	if err != nil {
 		return fmt.Errorf("install failed: %w", err)

cmd/flux/testdata/check/check_pre.golden

@@ -1,4 +1,3 @@
 ► checking prerequisites
-✔ kubectl {{ .clientVersion }} >=1.18.0-0
 ✔ Kubernetes {{ .serverVersion }} >=1.16.0-0
 ✔ prerequisites checks passed