Added bot command to enforce changelog requirements

bot/go.mod

@@ -23,4 +23,5 @@ require (
 	google.golang.org/appengine v1.6.7 // indirect
 	google.golang.org/protobuf v1.28.1 // indirect
 	gopkg.in/yaml.v3 v3.0.0 // indirect
+	k8s.io/utils v0.0.0-20230726121419-3b25d923346b
 )

bot/go.sum

@@ -167,3 +167,5 @@ gopkg.in/yaml.v3 v3.0.0 h1:hjy8E9ON/egN1tAYqKb61G10WtihqetD4sz2H+8nIeA=
 gopkg.in/yaml.v3 v3.0.0/go.mod h1:K4uyk7z7BCEPqu6E+C64Yfv1cQ7kz7rIZviUmN+EgEM=
 honnef.co/go/tools v0.0.0-20190102054323-c2f93a96b099/go.mod h1:rf3lG4BRIbNafJWhAfAdb/ePZxsR/4RtNHQocxwk9r4=
 honnef.co/go/tools v0.0.0-20190523083050-ea95bdfd59fc/go.mod h1:rf3lG4BRIbNafJWhAfAdb/ePZxsR/4RtNHQocxwk9r4=
+k8s.io/utils v0.0.0-20230726121419-3b25d923346b h1:sgn3ZU783SCgtaSJjpcVVlRqd6GSnlTLKgpAAttJvpI=
+k8s.io/utils v0.0.0-20230726121419-3b25d923346b/go.mod h1:OLgZIPagt7ERELqWJFomSt595RzquPNLL48iOWgYOg0=

bot/internal/bot/changelog.go

@@ -0,0 +1,123 @@
+/*
+Copyright 2022 Gravitational, Inc.
+
+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 bot
+
+import (
+	"context"
+	"fmt"
+	"log"
+	"regexp"
+	"strings"
+	"unicode"
+
+	"github.com/gravitational/trace"
+	"k8s.io/utils/strings/slices"
+)
+
+const NoChangelogLabel string = "no-changelog"
+const ChangelogPrefix string = "changelog: "
+const ChangelogRegex string = "(?mi)^changelog: .*"
+
+// Checks if the PR contains a changelog entry in the PR body, or a "no-changelog" label.
+//
+// A few tests are performed on the extracted changelog entry to ensure it conforms to a
+// common standard.
+func (b *Bot) CheckChangelog(ctx context.Context) error {
+	pull, err := b.c.GitHub.GetPullRequest(ctx,
+		b.c.Environment.Organization,
+		b.c.Environment.Repository,
+		b.c.Environment.Number,
+	)
+	if err != nil {
+		return trace.Wrap(err, "failed to retrieve pull request for https://github.com/%s/%s/pull/%d", b.c.Environment.Organization, b.c.Environment.Repository, b.c.Environment.Number)
+	}
+
+	if slices.Contains(pull.UnsafeLabels, NoChangelogLabel) {
+		log.Printf("PR contains %q label, skipping changelog check", NoChangelogLabel)
+		return nil
+	}
+
+	changelogEntry, err := b.getChangelogEntry(ctx, pull.UnsafeBody)
+	if err != nil {
+		return trace.Wrap(err, "failed to get changelog entry")
+	}
+
+	err = b.validateChangelogEntry(ctx, changelogEntry)
+	if err != nil {
+		return trace.Wrap(err, "failed to validate changelog entry")
+	}
+
+	return nil
+}
+
+func (b *Bot) getChangelogEntry(ctx context.Context, prBody string) (string, error) {
+	changelogRegex := regexp.MustCompile(ChangelogRegex)
+
+	changelogMatches := changelogRegex.FindAllString(prBody, 2) // Two or more changelog entries is invalid, so no need to search for more than two.
+	if len(changelogMatches) == 0 {
+		return "", b.logFailedCheck(ctx, "Changelog entry not found in the PR body. Please add a %q label to the PR, or a changelog line starting with `%s` followed by the changelog entry for the PR.", NoChangelogLabel, ChangelogPrefix)
+	}
+
+	if len(changelogMatches) > 1 {
+		return "", b.logFailedCheck(ctx, "Found two or more changelog entries in the PR body: %v", changelogMatches)
+	}
+
+	changelogEntry := changelogMatches[0][len(ChangelogPrefix):] // Case insensitive prefix removal
+	log.Printf("Found changelog entry %q", changelogEntry)
+	return changelogEntry, nil
+}
+
+// Checks for common issues with the changelog entry.
+// This is not intended to be comprehensive, rather, it is intended to cover the majority of problems.
+func (b *Bot) validateChangelogEntry(ctx context.Context, changelogEntry string) error {
+	if strings.TrimSpace(changelogEntry) == "" {
+		return b.logFailedCheck(ctx, "The changelog entry must contain one or more non-whitespace characters")
+	}
+
+	if !unicode.IsLetter([]rune(changelogEntry)[0]) {
+		return b.logFailedCheck(ctx, "The changelog entry must start with a letter")
+	}
+
+	if strings.HasPrefix(strings.ToLower(changelogEntry), "backport of") ||
+		strings.HasPrefix(strings.ToLower(changelogEntry), "backports") {
+		return b.logFailedCheck(ctx, "The changelog entry must contain the actual change, not a reference to the source PR of the backport.")
+	}
+
+	if strings.Contains(changelogEntry, "](") {
+		return b.logFailedCheck(ctx, "The changelog entry must not contain a Markdown link or image")
+	}
+
+	if strings.Contains(changelogEntry, "```") {
+		return b.logFailedCheck(ctx, "The changelog entry must not contain a multiline code block")
+	}
+
+	return nil
+}
+
+func (b *Bot) logFailedCheck(ctx context.Context, format string, args ...interface{}) error {
+	err := b.c.GitHub.CreateComment(ctx,
+		b.c.Environment.Organization,
+		b.c.Environment.Repository,
+		b.c.Environment.Number,
+		fmt.Sprintf(format, args...),
+	)
+	if err != nil {
+		return trace.Wrap(err, "failed to create or update the changelog comment")
+	}
+
+	return trace.Errorf(format, args...)
+}

bot/internal/bot/changelog_test.go

@@ -0,0 +1,207 @@
+/*
+Copyright 2021 Gravitational, Inc.
+
+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 bot
+
+import (
+	"context"
+	"fmt"
+	"strings"
+	"testing"
+
+	"github.com/gravitational/shared-workflows/bot/internal/env"
+	"github.com/gravitational/shared-workflows/bot/internal/github"
+	"github.com/stretchr/testify/require"
+)
+
+func TestChangelog(t *testing.T) {
+	t.Run("pass-no-changelog-label", func(t *testing.T) {
+		b, ctx := buildTestingFixtures()
+		b.c.GitHub.(*fakeGithub).pull.UnsafeLabels = []string{NoChangelogLabel}
+
+		err := b.CheckChangelog(ctx)
+		require.True(t, err == nil)
+	})
+}
+
+func TestGetChangelogEntry(t *testing.T) {
+	tests := []struct {
+		desc        string
+		body        string
+		shouldError bool
+		expected    string
+	}{
+		{
+			desc:        "pass-simple",
+			body:        strings.Join([]string{"some typical PR entry", fmt.Sprintf("%schangelog entry", ChangelogPrefix)}, "\n"),
+			shouldError: false,
+			expected:    "changelog entry",
+		},
+		{
+			desc:        "pass-case-invariant",
+			body:        strings.Join([]string{"some typical PR entry", fmt.Sprintf("%schangelog entry", strings.ToUpper(ChangelogPrefix))}, "\n"),
+			shouldError: false,
+			expected:    "changelog entry",
+		},
+		{
+			desc:        "pass-prefix-in-changelog-entry",
+			body:        strings.Join([]string{"some typical PR entry", strings.Repeat(ChangelogPrefix, 5)}, "\n"),
+			shouldError: false,
+			expected:    strings.Repeat(ChangelogPrefix, 4),
+		},
+		{
+			desc:        "pass-only-changelog-in-body",
+			body:        fmt.Sprintf("%schangelog entry", ChangelogPrefix),
+			shouldError: false,
+			expected:    "changelog entry",
+		},
+		{
+			desc:        "fail-if-no-body",
+			body:        "",
+			shouldError: true,
+		},
+		{
+			desc:        "fail-if-no-entry",
+			body:        "some typical PR entry",
+			shouldError: true,
+		},
+		{
+			desc:        "fail-if-multiple-entries",
+			body:        strings.Join([]string{ChangelogPrefix, ChangelogPrefix, ChangelogPrefix}, "\n"),
+			shouldError: true,
+		},
+	}
+	for _, test := range tests {
+		t.Run(test.desc, func(t *testing.T) {
+			b, ctx := buildTestingFixtures()
+
+			changelogEntry, err := b.getChangelogEntry(ctx, test.body)
+			require.Equal(t, test.shouldError, err != nil)
+			if !test.shouldError {
+				require.Equal(t, test.expected, changelogEntry)
+			}
+		})
+	}
+}
+
+func TestValidateGetChangelogEntry(t *testing.T) {
+	tests := []struct {
+		desc        string
+		entry       string
+		shouldError bool
+	}{
+		{
+			desc:        "pass-simple",
+			entry:       "Changelog entry",
+			shouldError: false,
+		},
+		{
+			desc:        "pass-markdown-single-line-code-block",
+			entry:       "Changelog `entry`",
+			shouldError: false,
+		},
+		{
+			desc:        "fail-empty",
+			entry:       "",
+			shouldError: true,
+		},
+		{
+			desc:        "fail-whitespace",
+			entry:       " \t ",
+			shouldError: true,
+		},
+		{
+			desc:        "fail-non-alphabetical-starting-character",
+			entry:       "1234Changelog entry",
+			shouldError: true,
+		},
+		{
+			desc:        "fail-refers-to-backport",
+			entry:       "Backport of #1234",
+			shouldError: true,
+		},
+		{
+			desc:        "fail-ends-with-markdown-link",
+			entry:       "Changelog [entry](https://some-link.com).",
+			shouldError: true,
+		},
+		{
+			desc:        "fail-ends-with-markdown-image",
+			entry:       "Changelog ![entry](https://some-link.com).",
+			shouldError: true,
+		},
+		{
+			desc:        "fail-ends-with-markdown-header",
+			entry:       "## Changelog entry",
+			shouldError: true,
+		},
+		{
+			desc:        "fail-ends-with-markdown-ordered-list",
+			entry:       "1. Changelog entry",
+			shouldError: true,
+		},
+		{
+			desc:        "fail-ends-with-markdown-unordered-list",
+			entry:       "- Changelog entry",
+			shouldError: true,
+		},
+		{
+			desc:        "fail-ends-with-markdown-multiline-code-block",
+			entry:       "Changelog entry ```",
+			shouldError: true,
+		},
+	}
+	for _, test := range tests {
+		t.Run(test.desc, func(t *testing.T) {
+			b, ctx := buildTestingFixtures()
+
+			err := b.validateChangelogEntry(ctx, test.entry)
+			require.Equal(t, test.shouldError, err != nil)
+		})
+	}
+}
+
+func TestLogFailedCheck(t *testing.T) {
+	t.Run("fail-contains-passed-message", func(t *testing.T) {
+		b, ctx := buildTestingFixtures()
+
+		err := b.logFailedCheck(ctx, "error %s", "message")
+		require.ErrorContains(t, err, "error message")
+	})
+}
+
+func buildTestingFixtures() (*Bot, context.Context) {
+	return &Bot{
+		c: &Config{
+			Environment: &env.Environment{
+				Organization: "foo",
+				Author:       "9",
+				Repository:   "bar",
+				Number:       0,
+				UnsafeBase:   "branch/v8",
+				UnsafeHead:   "fix",
+			},
+			GitHub: &fakeGithub{
+				comments: []github.Comment{
+					{
+						Author: "[email protected]",
+						Body:   "PR comment body",
+					},
+				},
+			},
+		},
+	}, context.Background()
+}

bot/main.go

@@ -78,6 +78,8 @@ func main() {
 		err = b.CalculateBinarySizes(ctx, flags.buildDir, flags.artifacts, out)
 	case "bloat":
 		err = b.BloatCheck(ctx, flags.baseStats, flags.buildDir, flags.artifacts, os.Stdout)
+	case "changelog":
+		err = b.CheckChangelog(ctx)
 	default:
 		err = trace.BadParameter("unknown workflow: %v", flags.workflow)
 	}