cmd/k8s-operator/{deploy,crdsforhelm}: generate Helm templates with the Connector CRD

Add functionality to insert Connector CRD into Helm templates
so that a Helm chart package can be built that contains the CRD.
Add an 'installCRDs' configuration knob to the Helm chart
to allow users to optionally NOT install the CRD with the chart.

Updates tailscale/tailscale#10641

Signed-off-by: Irbe Krumina <irbe@tailscale.com>

cmd/k8s-operator/crdsforhelm/main.go

@@ -0,0 +1,75 @@
+// Copyright (c) Tailscale Inc & AUTHORS
+// SPDX-License-Identifier: BSD-3-Clause
+
+//go:build !plan9 && !windows
+
+package main
+
+import (
+	"fmt"
+	"log"
+	"os"
+	"path/filepath"
+)
+
+const (
+	operatorDeploymentFilesPath = "cmd/k8s-operator/deploy"
+	crdPath                     = operatorDeploymentFilesPath + "/crds/tailscale.com_connectors.yaml"
+	helmTemplatesPath           = operatorDeploymentFilesPath + "/chart/templates"
+	crdTemplatePath             = helmTemplatesPath + "/connectors.yaml"
+
+	helmConditionalStart = "{{ if and .Values.installCRDs -}}\n"
+	helmConditionalEnd   = "{{- end -}}"
+)
+
+func main() {
+
+	if len(os.Args) != 3 {
+		log.Fatal("usage: ./chartgen [generate|cleanup] <path to tailscale.com source directory>")
+	}
+	baseDir := os.Args[2]
+	switch os.Args[1] {
+	case "generate":
+		if err := generate(baseDir); err != nil {
+			log.Fatalf("error generating CRD template: %v", err)
+		}
+	case "cleanup":
+		if err := cleanup(baseDir); err != nil {
+			log.Fatalf("error cleaning CRD template: %v", err)
+		}
+	default:
+		log.Fatalf("unknown command %s, known commands are 'generate' and 'cleanup'", os.Args[1])
+	}
+}
+
+func generate(baseDir string) error {
+	log.Print("Placing Connector CRD into Helm templates..")
+	chartBytes, err := os.ReadFile(filepath.Join(baseDir, crdPath))
+	if err != nil {
+		return fmt.Errorf("error reading CRD contents: %w", err)
+	}
+	// Place a new temporary Helm template file with the templated CRD
+	// contents into Helm templates.
+	file, err := os.Create(filepath.Join(baseDir, crdTemplatePath))
+	if err != nil {
+		return fmt.Errorf("error creating CRD template file: %w", err)
+	}
+	if _, err := file.Write([]byte(helmConditionalStart)); err != nil {
+		return fmt.Errorf("error writing helm if statement start: %w", err)
+	}
+	if _, err := file.Write(chartBytes); err != nil {
+		return fmt.Errorf("error writing chart bytes: %w", err)
+	}
+	if _, err := file.Write([]byte(helmConditionalEnd)); err != nil {
+		return fmt.Errorf("error writing helm if-statement end: %w", err)
+	}
+	return nil
+}
+
+func cleanup(baseDir string) error {
+	log.Print("Cleaning up CRD from Helm templates")
+	if err := os.Remove(filepath.Join(baseDir, crdTemplatePath)); err != nil && !os.IsNotExist(err) {
+		return fmt.Errorf("error cleaning up CRD template: %w", err)
+	}
+	return nil
+}

cmd/k8s-operator/crdsforhelm/main_test.go

@@ -0,0 +1,68 @@
+// Copyright (c) Tailscale Inc & AUTHORS
+// SPDX-License-Identifier: BSD-3-Clause
+
+//go:build !plan9 && !windows
+
+package main
+
+import (
+	"bytes"
+	"os"
+	"os/exec"
+	"path/filepath"
+	"strings"
+	"testing"
+)
+
+func TestGenerate(t *testing.T) {
+	base, err := os.Getwd()
+	base = filepath.Join(base, "../../../")
+	if err != nil {
+		t.Fatalf("error getting current working directory: %v", err)
+	}
+	defer cleanup(base)
+	if err := generate(base); err != nil {
+		t.Fatalf("CRD template generation: %v", err)
+	}
+
+	tempDir := t.TempDir()
+	helmCLIPath := filepath.Join(base, "tool/helm")
+	helmChartTemplatesPath := filepath.Join(base, "cmd/k8s-operator/deploy/chart")
+	helmPackageCmd := exec.Command(helmCLIPath, "package", helmChartTemplatesPath, "--destination", tempDir, "--version", "0.0.1")
+	helmPackageCmd.Stderr = os.Stderr
+	helmPackageCmd.Stdout = os.Stdout
+	if err := helmPackageCmd.Run(); err != nil {
+		t.Fatalf("error packaging Helm chart: %v", err)
+	}
+	helmPackagePath := filepath.Join(tempDir, "tailscale-operator-0.0.1.tgz")
+	helmLintCmd := exec.Command(helmCLIPath, "lint", helmPackagePath)
+	helmLintCmd.Stderr = os.Stderr
+	helmLintCmd.Stdout = os.Stdout
+	if err := helmLintCmd.Run(); err != nil {
+		t.Fatalf("Helm chart linter failed: %v", err)
+	}
+
+	// Test that default Helm install contains the CRD
+	installContentsWithCRD := bytes.NewBuffer([]byte{})
+	helmTemplateWithCRDCmd := exec.Command(helmCLIPath, "template", helmPackagePath)
+	helmTemplateWithCRDCmd.Stderr = os.Stderr
+	helmTemplateWithCRDCmd.Stdout = installContentsWithCRD
+	if err := helmTemplateWithCRDCmd.Run(); err != nil {
+		t.Fatalf("templating Helm chart with CRDs failed: %v", err)
+	}
+	if !strings.Contains(installContentsWithCRD.String(), "name: connectors.tailscale.com") {
+		t.Errorf("CRD not found in default chart install")
+	}
+
+	// Test that CRD can be excluded from Helm chart install
+	installContentsWithoutCRD := bytes.NewBuffer([]byte{})
+	helmTemplateWithoutCRDCmd := exec.Command(helmCLIPath, "template", helmPackagePath, "--set", "installCRDs=false")
+	helmTemplateWithoutCRDCmd.Stderr = os.Stderr
+	helmTemplateWithoutCRDCmd.Stdout = installContentsWithoutCRD
+	if err := helmTemplateWithoutCRDCmd.Run(); err != nil {
+		t.Fatalf("templating Helm chart without CRDs failed: %v", err)
+	}
+	if strings.Contains(installContentsWithoutCRD.String(), "name: connectors.tailscale.com") {
+		t.Errorf("CRD found in chart install that should not contain a CRD")
+	}
+}

cmd/k8s-operator/deploy/chart/values.yaml

@@ -9,11 +9,15 @@ oauth: {}
   # clientSecret: ""
 
 # enableConnector determines whether the operator should reconcile
-# connector.tailscale.com custom resources. If set to true you have to install
-# connector CRD in a separate step.
-# You can do so by running 'kubectl apply -f ./cmd/k8s-operator/deploy/crds'.
+# connector.tailscale.com custom resources.
 enableConnector: "false"
 
+# installCRDs determines whether tailscale.com CRDs should be installed as part
+# of chart installation. We do not use Helm's CRD installation mechanism as that
+# does not allow for upgrading CRDs.
+# https://helm.sh/docs/chart_best_practices/custom_resource_definitions/
+installCRDs: "true"
+
 operatorConfig:
   image:
     repo: tailscale/k8s-operator