Add release notes generation

RELEASE.md

@@ -5,5 +5,6 @@ https://github.com/kubernetes-sigs/controller-runtime/blob/main/RELEASE.md
 
 1. Create a new release branch from main: `git checkout -b release-<MAJOR.MINOR>`
 2. Push the new branch to the remote repository: ` git push --set-upstream origin release-<MAJOR.MINOR>`
-3. Generate the release notes: `go run sigs.k8s.io/kubebuilder-release-tools/notes --project hsbc/cost-manager`
-4. Create a new release in GitHub from the release branch, pasting the generated release notes
+3. Fetch all tags from the remote: `git fetch --all --tags`
+4. Generate the release notes from the previous tag: `go run ./hack/notes --from vMAJOR.MINOR.PATCH`
+5. Create a new release in GitHub from the release branch, pasting the generated release notes

hack/notes/notes.go

@@ -0,0 +1,108 @@
+package main
+
+import (
+	"flag"
+	"fmt"
+	"os"
+	"os/exec"
+	"strings"
+)
+
+/*
+This tool generates release notes from the commits between two Git references
+*/
+
+var (
+	warnings      = ":warning: Breaking Changes"
+	features      = ":sparkles: New Features"
+	bugs          = ":bug: Bug Fixes"
+	documentation = ":book: Documentation"
+	others        = ":seedling: Others"
+	unknown       = ":question: Sort these by hand"
+
+	outputOrder = []string{
+		warnings,
+		features,
+		bugs,
+		documentation,
+		others,
+		unknown,
+	}
+)
+
+func main() {
+	from := flag.String("from", "", "Include commits starting from this Git reference")
+	to := flag.String("to", "", "Include commits up to and including this Git reference. Defaults to HEAD")
+	flag.Parse()
+
+	err := run(*from, *to)
+	if err != nil {
+		os.Exit(1)
+	}
+}
+
+func run(from, to string) error {
+	if from == "" {
+		return fmt.Errorf("Git reference to start from must be specified")
+	}
+	if to == "" {
+		to = "HEAD"
+	}
+
+	cmd := exec.Command("git", "rev-list", fmt.Sprintf("%s..%s", from, to), "--pretty=format:%B")
+	out, err := cmd.CombinedOutput()
+	if err != nil {
+		return err
+	}
+
+	commits := map[string][]string{}
+	for _, output := range outputOrder {
+		commits[output] = []string{}
+	}
+	outLines := strings.Split(string(out), "\n")
+	for i, line := range outLines {
+		// If we have found a commit then we pick the next line
+		if !strings.HasPrefix(line, "commit ") {
+			continue
+		}
+		title := outLines[i+1]
+		var key string
+		switch {
+		case strings.HasPrefix(title, "⚠️"):
+			key = warnings
+			title = strings.TrimPrefix(title, "⚠️")
+		case strings.HasPrefix(title, "✨"):
+			key = features
+			title = strings.TrimPrefix(title, "✨")
+		case strings.HasPrefix(title, "🐛"):
+			key = bugs
+			title = strings.TrimPrefix(title, "🐛")
+		case strings.HasPrefix(title, "📖"):
+			key = documentation
+			title = strings.TrimPrefix(title, "📖")
+		case strings.HasPrefix(title, "🌱"):
+			key = others
+			title = strings.TrimPrefix(title, "🌱")
+		default:
+			key = unknown
+		}
+		title = strings.TrimSpace(title)
+		commits[key] = append(commits[key], title)
+	}
+
+	fmt.Printf("## Changes since [%s](https://github.com/hsbc/cost-manager/releases/%s)\n\n", from, from)
+	for _, key := range outputOrder {
+		commits := commits[key]
+		if len(commits) == 0 {
+			continue
+		}
+
+		fmt.Printf("### %s\n\n", key)
+		for _, commit := range commits {
+			fmt.Printf("- %s\n", commit)
+		}
+		fmt.Println()
+	}
+
+	return nil
+}