Merge pull request #4983 from gofogo/chore-4260

chore(docs): docs/flags.md generation

Makefile

@@ -160,3 +160,8 @@ release.prod: test
 .PHONY: ko
 ko:
 	scripts/install-ko.sh
+
+# generate-flags-documentation: Generate documentation (docs/flags.md)
+.PHONE: generate-flags-documentation
+generate-flags-documentation:
+	go run internal/gen/docs/flags/main.go

internal/gen/docs/flags/main.go

@@ -0,0 +1,115 @@
+/*
+Copyright 2017 The Kubernetes Authors.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+package main
+
+import (
+	"bytes"
+	"fmt"
+	"os"
+	"strings"
+	"text/template"
+
+	cfg "sigs.k8s.io/external-dns/pkg/apis/externaldns"
+)
+
+type Flag struct {
+	Name        string
+	Description string
+}
+type Flags []Flag
+
+// AddFlag adds a new flag to the Flags struct
+func (f *Flags) addFlag(name, description string) {
+	*f = append(*f, Flag{Name: name, Description: description})
+}
+
+const markdownTemplate = `# Flags
+
+<!-- THIS FILE MUST NOT BE EDITED BY HAND -->
+<!-- ON NEW FLAG ADDED PLEASE RUN 'make generate-flags-documentation' -->
+
+| Flag | Description  |
+| :------ | :----------- |
+{{- range . }}
+| {{ .Name }} | {{ .Description }} | {{- end -}}
+`
+
+// It generates a markdown file
+// with the supported flags and writes it to the 'docs/flags.md' file.
+// to re-generate `docs/flags.md` execute 'go run internal/gen/main.go'
+func main() {
+	testPath, _ := os.Getwd()
+	path := fmt.Sprintf("%s/docs/flags.md", testPath)
+	fmt.Printf("generate file '%s' with supported flags\n", path)
+
+	flags := computeFlags()
+	content, err := flags.generateMarkdownTable()
+	if err != nil {
+		_ = fmt.Errorf("failed to generate markdown file '%s': %v\n", path, err.Error())
+	}
+	_ = writeToFile(path, content)
+}
+
+func computeFlags() Flags {
+	app := cfg.App(&cfg.Config{})
+	modelFlags := app.Model().Flags
+
+	flags := Flags{}
+
+	for _, flag := range modelFlags {
+		// do not include helpers and completion flags
+		if strings.Contains(flag.Name, "help") || strings.Contains(flag.Name, "completion-") {
+			continue
+		}
+		flagString := ""
+		flagName := flag.Name
+		if flag.IsBoolFlag() {
+			flagName = "[no-]" + flagName
+		}
+		flagString += fmt.Sprintf("--%s", flagName)
+
+		if !flag.IsBoolFlag() {
+			flagString += fmt.Sprintf("=%s", flag.FormatPlaceHolder())
+		}
+		flags.addFlag(fmt.Sprintf("`%s`", flagString), flag.HelpWithEnvar())
+	}
+	return flags
+}
+
+func (f *Flags) generateMarkdownTable() (string, error) {
+	tmpl := template.Must(template.New("flags.md.tpl").Parse(markdownTemplate))
+
+	var b bytes.Buffer
+	err := tmpl.Execute(&b, f)
+	if err != nil {
+		return "", err
+	}
+	return b.String(), nil
+}
+
+func writeToFile(filename string, content string) error {
+	file, fileErr := os.Create(filename)
+	if fileErr != nil {
+		_ = fmt.Errorf("failed to create file: %v", fileErr)
+	}
+	defer file.Close()
+	_, writeErr := file.WriteString(content)
+	if writeErr != nil {
+		_ = fmt.Errorf("failed to write to file: %s", filename)
+	}
+	return nil
+}

internal/gen/docs/flags/main_test.go

@@ -0,0 +1,92 @@
+/*
+Copyright 2017 The Kubernetes Authors.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+package main
+
+import (
+	"fmt"
+	"io/fs"
+	"os"
+	"strings"
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+)
+
+const pathToDocs = "%s/../../../../docs"
+
+func TestComputeFlags(t *testing.T) {
+	flags := computeFlags()
+
+	if len(flags) == 0 {
+		t.Errorf("Expected non-zero flags, got %d", len(flags))
+	}
+
+	for _, flag := range flags {
+		if strings.Contains(flag.Name, "help") || strings.Contains(flag.Name, "completion-") {
+			t.Errorf("Unexpected flag: %s", flag.Name)
+		}
+	}
+}
+
+func TestGenerateMarkdownTableRenderer(t *testing.T) {
+	flags := Flags{
+		{Name: "flag1", Description: "description1"},
+	}
+
+	got, err := flags.generateMarkdownTable()
+	assert.NoError(t, err)
+
+	assert.Contains(t, got, "<!-- THIS FILE MUST NOT BE EDITED BY HAND -->")
+	assert.Contains(t, got, "| flag1 | description1 |")
+}
+
+func TestFlagsMdExists(t *testing.T) {
+	testPath, _ := os.Getwd()
+	fsys := os.DirFS(fmt.Sprintf(pathToDocs, testPath))
+	fileName := "flags.md"
+	st, err := fs.Stat(fsys, fileName)
+	assert.NoError(t, err, "expected file %s to exist", fileName)
+	assert.Equal(t, fileName, st.Name())
+}
+
+func TestFlagsMdUpToDate(t *testing.T) {
+	testPath, _ := os.Getwd()
+	fsys := os.DirFS(fmt.Sprintf(pathToDocs, testPath))
+	fileName := "flags.md"
+	expected, err := fs.ReadFile(fsys, fileName)
+	assert.NoError(t, err, "expected file %s to exist", fileName)
+
+	flags := computeFlags()
+	actual, err := flags.generateMarkdownTable()
+	assert.NoError(t, err)
+	assert.True(t, len(expected) == len(actual), "expected file '%s' to be up to date. execute 'make generate-flags-documentation", fileName)
+}
+
+func TestFlagsMdExtraFlagAdded(t *testing.T) {
+	testPath, _ := os.Getwd()
+	fsys := os.DirFS(fmt.Sprintf(pathToDocs, testPath))
+	filePath := "flags.md"
+	expected, err := fs.ReadFile(fsys, filePath)
+	assert.NoError(t, err, "expected file %s to exist", filePath)
+
+	flags := computeFlags()
+	flags.addFlag("new-flag", "description2")
+	actual, err := flags.generateMarkdownTable()
+
+	assert.NoError(t, err)
+	assert.NotEqual(t, string(expected), actual)
+}

mkdocs.yml

@@ -12,6 +12,7 @@ nav:
       - Changelog: charts/external-dns/CHANGELOG.md
   - About:
       - FAQ: docs/faq.md
+      - Flags: docs/flags.md
       - Out of Incubator: docs/20190708-external-dns-incubator.md
       - Code of Conduct: code-of-conduct.md
       - License: LICENSE.md

pkg/apis/externaldns/types.go

@@ -400,6 +400,17 @@ func allLogLevelsAsStrings() []string {
 
 // ParseFlags adds and parses flags from command line
 func (cfg *Config) ParseFlags(args []string) error {
+	app := App(cfg)
+
+	_, err := app.Parse(args)
+	if err != nil {
+		return err
+	}
+
+	return nil
+}
+
+func App(cfg *Config) *kingpin.Application {
 	app := kingpin.New("external-dns", "ExternalDNS synchronizes exposed Kubernetes Services and Ingresses with DNS providers.\n\nNote that all flags may be replaced with env vars - `--flag` -> `EXTERNAL_DNS_FLAG=1` or `--flag value` -> `EXTERNAL_DNS_FLAG=value`")
 	app.Version(Version)
 	app.DefaultEnvars()
@@ -603,10 +614,5 @@ func (cfg *Config) ParseFlags(args []string) error {
 
 	app.Flag("webhook-server", "When enabled, runs as a webhook server instead of a controller. (default: false).").BoolVar(&cfg.WebhookServer)
 
-	_, err := app.Parse(args)
-	if err != nil {
-		return err
-	}
-
-	return nil
+	return app
 }