Automate the Hugo release process

This commit adds a work flow aroung GoReleaser to get the Hugo release process automated and more uniform:

* It can be run fully automated or in two steps to allow for manual edits of the relase notes.
* It supports both patch and full releases.
* It fetches author, issue, repo info. etc. for the release notes from GitHub.
* The file names produced are mainly the same as before, but we no use tar.gz as archive for all Unix versions.
* There isn't a fully automated CI setup in place yet, but the release tag is marked in the commit message with "[ci deploy]"

Fixes #3358

releaser/releaser.go

@@ -0,0 +1,267 @@
+// Copyright 2017-present The Hugo Authors. All rights reserved.
+//
+// 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 releaser implements a set of utilities and a wrapper around Goreleaser
+// to help automate the Hugo release process.
+package releaser
+
+import (
+	"errors"
+	"fmt"
+	"io/ioutil"
+	"log"
+	"os"
+	"os/exec"
+	"path/filepath"
+	"regexp"
+	"strings"
+
+	"github.com/spf13/hugo/helpers"
+)
+
+const commitPrefix = "releaser:"
+
+type ReleaseHandler struct {
+	patch       int
+	step        int
+	skipPublish bool
+}
+
+func (r ReleaseHandler) shouldRelease() bool {
+	return r.step < 1 || r.shouldContinue()
+}
+
+func (r ReleaseHandler) shouldContinue() bool {
+	return r.step == 2
+}
+
+func (r ReleaseHandler) shouldPrepare() bool {
+	return r.step < 1 || r.step == 1
+}
+
+func (r ReleaseHandler) calculateVersions(current helpers.HugoVersion) (helpers.HugoVersion, helpers.HugoVersion) {
+	var (
+		newVersion   = current
+		finalVersion = current
+	)
+
+	newVersion.Suffix = ""
+
+	if r.shouldContinue() {
+		// The version in the current code base is in the state we want for
+		// the release.
+		if r.patch == 0 {
+			finalVersion = newVersion.Next()
+		}
+	} else if r.patch > 0 {
+		newVersion = helpers.CurrentHugoVersion.NextPatchLevel(r.patch)
+	} else {
+		finalVersion = newVersion.Next()
+	}
+
+	finalVersion.Suffix = "-DEV"
+
+	return newVersion, finalVersion
+}
+
+func New(patch, step int, skipPublish bool) *ReleaseHandler {
+	return &ReleaseHandler{patch: patch, step: step, skipPublish: skipPublish}
+}
+
+func (r *ReleaseHandler) Run() error {
+	if os.Getenv("GITHUB_TOKEN") == "" {
+		return errors.New("GITHUB_TOKEN not set, create one here with the repo scope selected: https://github.com/settings/tokens/new")
+	}
+
+	newVersion, finalVersion := r.calculateVersions(helpers.CurrentHugoVersion)
+
+	version := newVersion.String()
+	tag := "v" + version
+
+	// Exit early if tag already exists
+	out, err := git("tag", "-l", tag)
+
+	if err != nil {
+		return err
+	}
+
+	if strings.Contains(out, tag) {
+		return fmt.Errorf("Tag %q already exists", tag)
+	}
+
+	var gitCommits gitInfos
+
+	if r.shouldPrepare() || r.shouldRelease() {
+		gitCommits, err = getGitInfos(true)
+		if err != nil {
+			return err
+		}
+	}
+
+	if r.shouldPrepare() {
+		if err := bumpVersions(newVersion); err != nil {
+			return err
+		}
+
+		if _, err := git("commit", "-a", "-m", fmt.Sprintf("%s Bump versions for release of %s\n\n[ci skip]", commitPrefix, newVersion)); err != nil {
+			return err
+		}
+
+		releaseNotesFile, err := writeReleaseNotesToDocsTemp(version, gitCommits)
+		if err != nil {
+			return err
+		}
+
+		if _, err := git("add", releaseNotesFile); err != nil {
+			return err
+		}
+		if _, err := git("commit", "-m", fmt.Sprintf("%s Add relase notes draft for release of %s\n\n[ci skip]", commitPrefix, newVersion)); err != nil {
+			return err
+		}
+	}
+
+	if !r.shouldRelease() {
+		fmt.Println("Skip release ... Use --state=2 to continue.")
+		return nil
+	}
+
+	releaseNotesFile := getRelaseNotesDocsTempFilename(version)
+
+	// Write the release notes to the docs site as well.
+	docFile, err := writeReleaseNotesToDocs(version, releaseNotesFile)
+	if err != nil {
+		return err
+	}
+
+	if _, err := git("add", docFile); err != nil {
+		return err
+	}
+	if _, err := git("commit", "-m", fmt.Sprintf("%s Add relase notes to /docs for release of %s\n\n[ci skip]", commitPrefix, newVersion)); err != nil {
+		return err
+	}
+
+	if _, err := git("tag", "-a", tag, "-m", fmt.Sprintf("%s %s [ci deploy]", commitPrefix, newVersion)); err != nil {
+		return err
+	}
+
+	if err := r.release(releaseNotesFile); err != nil {
+		return err
+	}
+
+	if err := bumpVersions(finalVersion); err != nil {
+		return err
+	}
+
+	// No longer needed.
+	if err := os.Remove(releaseNotesFile); err != nil {
+		return err
+	}
+
+	if _, err := git("commit", "-a", "-m", fmt.Sprintf("%s Prepare repository for %s\n\n[ci skip]", commitPrefix, finalVersion)); err != nil {
+		return err
+	}
+
+	return nil
+}
+
+func (r *ReleaseHandler) release(releaseNotesFile string) error {
+	cmd := exec.Command("goreleaser", "--release-notes", releaseNotesFile, "--skip-publish="+fmt.Sprint(r.skipPublish))
+	cmd.Stdout = os.Stdout
+	cmd.Stderr = os.Stderr
+	err := cmd.Run()
+	if err != nil {
+		return fmt.Errorf("goreleaser failed: %s", err)
+	}
+	return nil
+}
+
+func bumpVersions(ver helpers.HugoVersion) error {
+	fromDev := ""
+	toDev := ""
+
+	if ver.Suffix != "" {
+		toDev = "-DEV"
+	} else {
+		fromDev = "-DEV"
+	}
+
+	if err := replaceInFile("helpers/hugo.go",
+		`Number:(\s{4,})(.*),`, fmt.Sprintf(`Number:${1}%.2f,`, ver.Number),
+		`PatchLevel:(\s*)(.*),`, fmt.Sprintf(`PatchLevel:${1}%d,`, ver.PatchLevel),
+		fmt.Sprintf(`Suffix:(\s{4,})"%s",`, fromDev), fmt.Sprintf(`Suffix:${1}"%s",`, toDev)); err != nil {
+		return err
+	}
+
+	snapcraftGrade := "stable"
+	if ver.Suffix != "" {
+		snapcraftGrade = "devel"
+	}
+	if err := replaceInFile("snapcraft.yaml",
+		`version: "(.*)"`, fmt.Sprintf(`version: "%s"`, ver),
+		`grade: (.*) #`, fmt.Sprintf(`grade: %s #`, snapcraftGrade)); err != nil {
+		return err
+	}
+
+	var minVersion string
+	if ver.Suffix != "" {
+		// People use the DEV version in daily use, and we cannot create new themes
+		// with the next version before it is released.
+		minVersion = ver.Prev().String()
+	} else {
+		minVersion = ver.String()
+	}
+
+	if err := replaceInFile("commands/new.go",
+		`min_version = "(.*)"`, fmt.Sprintf(`min_version = "%s"`, minVersion)); err != nil {
+		return err
+	}
+
+	// docs/config.toml
+	if err := replaceInFile("docs/config.toml",
+		`release = "(.*)"`, fmt.Sprintf(`release = "%s"`, ver)); err != nil {
+		return err
+	}
+
+	return nil
+}
+
+func replaceInFile(filename string, oldNew ...string) error {
+	fullFilename := hugoFilepath(filename)
+	fi, err := os.Stat(fullFilename)
+	if err != nil {
+		return err
+	}
+
+	b, err := ioutil.ReadFile(fullFilename)
+	if err != nil {
+		return err
+	}
+	newContent := string(b)
+
+	for i := 0; i < len(oldNew); i += 2 {
+		re := regexp.MustCompile(oldNew[i])
+		newContent = re.ReplaceAllString(newContent, oldNew[i+1])
+	}
+
+	return ioutil.WriteFile(fullFilename, []byte(newContent), fi.Mode())
+
+	return nil
+}
+
+func hugoFilepath(filename string) string {
+	pwd, err := os.Getwd()
+	if err != nil {
+		log.Fatal(err)
+	}
+	return filepath.Join(pwd, filename)
+}