feat: support pull request templates (#4105)

check if there is a `.github/PULL_REQUEST_TEMPLATE.md` file, and use it
as body of the pull request if there is.

---------

Signed-off-by: Carlos Alexandro Becker <caarlos0@users.noreply.github.com>

internal/client/github.go

@@ -166,6 +166,22 @@ func headString(base, head Repo) string {
 	}, ":")
 }
 
+func (c *githubClient) getPRTemplate(ctx *context.Context, repo Repo) (string, error) {
+	content, _, _, err := c.client.Repositories.GetContents(
+		ctx, repo.Owner, repo.Name,
+		".github/PULL_REQUEST_TEMPLATE.md",
+		&github.RepositoryContentGetOptions{
+			Ref: repo.Branch,
+		},
+	)
+	if err != nil {
+		return "", err
+	}
+	return content.GetContent()
+}
+
+const prFooter = "###### Automated with [GoReleaser](https://goreleaser.com)"
+
 func (c *githubClient) OpenPullRequest(
 	ctx *context.Context,
 	base, head Repo,
@@ -180,26 +196,38 @@ func (c *githubClient) OpenPullRequest(
 		}
 		base.Branch = def
 	}
+	tpl, err := c.getPRTemplate(ctx, base)
+	if err != nil {
+		log.WithError(err).Debug("no pull request template found...")
+	}
+	if len(tpl) > 0 {
+		log.Info("got a pr template")
+	}
 	log := log.
 		WithField("base", headString(base, Repo{})).
 		WithField("head", headString(base, head)).
 		WithField("draft", draft)
 	log.Info("opening pull request")
-	pr, res, err := c.client.PullRequests.Create(ctx, base.Owner, base.Name, &github.NewPullRequest{
-		Title: github.String(title),
-		Base:  github.String(base.Branch),
-		Head:  github.String(headString(base, head)),
-		Body:  github.String("Automatically generated by [GoReleaser](https://goreleaser.com)"),
-		Draft: github.Bool(draft),
-	})
+	pr, res, err := c.client.PullRequests.Create(
+		ctx,
+		firstNonEmpty(base.Owner, head.Owner),
+		firstNonEmpty(base.Name, head.Name),
+		&github.NewPullRequest{
+			Title: github.String(title),
+			Base:  github.String(base.Branch),
+			Head:  github.String(headString(base, head)),
+			Body:  github.String(strings.Join([]string{tpl, prFooter}, "\n")),
+			Draft: github.Bool(draft),
+		},
+	)
 	if err != nil {
 		if res.StatusCode == 422 {
-			log.Warn("PR already exists, doing nothing...")
+			log.WithError(err).Warn("pull request validation failed")
 			return nil
 		}
 		return fmt.Errorf("could not create pull request: %w", err)
 	}
-	log.WithField("url", pr.GetHTMLURL()).Info("opened")
+	log.WithField("url", pr.GetHTMLURL()).Info("pull request created")
 	return nil
 }
 
@@ -240,6 +268,7 @@ func (c *githubClient) CreateFile(
 	log.
 		WithField("repository", repo.String()).
 		WithField("branch", repo.Branch).
+		WithField("file", path).
 		Info("pushing")
 
 	if defBranch != branch && branch != "" {

internal/client/github_test.go

@@ -1,6 +1,7 @@
 package client
 
 import (
+	"encoding/base64"
 	"encoding/json"
 	"fmt"
 	"io"
@@ -405,10 +406,22 @@ func TestCloseMilestone(t *testing.T) {
 	require.NoError(t, client.CloseMilestone(ctx, repo, "v1.13.0"))
 }
 
+const testPRTemplate = "fake template\n- [ ] mark this\n---"
+
 func TestOpenPullRequestCrossRepo(t *testing.T) {
 	srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
 		defer r.Body.Close()
 
+		if r.URL.Path == "/repos/someone/something/contents/.github/PULL_REQUEST_TEMPLATE.md" {
+			content := github.RepositoryContent{
+				Encoding: github.String("base64"),
+				Content:  github.String(base64.StdEncoding.EncodeToString([]byte(testPRTemplate))),
+			}
+			bts, _ := json.Marshal(content)
+			_, _ = w.Write(bts)
+			return
+		}
+
 		if r.URL.Path == "/repos/someone/something/pulls" {
 			got, err := io.ReadAll(r.Body)
 			require.NoError(t, err)
@@ -416,6 +429,7 @@ func TestOpenPullRequestCrossRepo(t *testing.T) {
 			require.NoError(t, json.Unmarshal(got, &pr))
 			require.Equal(t, "main", pr.GetBase())
 			require.Equal(t, "someoneelse:something:foo", pr.GetHead())
+			require.Equal(t, testPRTemplate+"\n"+prFooter, pr.GetBody())
 			r, err := os.Open("testdata/github/pull.json")
 			require.NoError(t, err)
 			_, err = io.Copy(w, r)
@@ -457,6 +471,16 @@ func TestOpenPullRequestHappyPath(t *testing.T) {
 	srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
 		defer r.Body.Close()
 
+		if r.URL.Path == "/repos/someone/something/contents/.github/PULL_REQUEST_TEMPLATE.md" {
+			content := github.RepositoryContent{
+				Encoding: github.String("base64"),
+				Content:  github.String(base64.StdEncoding.EncodeToString([]byte(testPRTemplate))),
+			}
+			bts, _ := json.Marshal(content)
+			_, _ = w.Write(bts)
+			return
+		}
+
 		if r.URL.Path == "/repos/someone/something/pulls" {
 			r, err := os.Open("testdata/github/pull.json")
 			require.NoError(t, err)
@@ -495,6 +519,11 @@ func TestOpenPullRequestNoBaseBranchDraft(t *testing.T) {
 	srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
 		defer r.Body.Close()
 
+		if r.URL.Path == "/repos/someone/something/contents/.github/PULL_REQUEST_TEMPLATE.md" {
+			w.WriteHeader(http.StatusNotFound)
+			return
+		}
+
 		if r.URL.Path == "/repos/someone/something/pulls" {
 			got, err := io.ReadAll(r.Body)
 			require.NoError(t, err)
@@ -548,6 +577,11 @@ func TestOpenPullRequestPRExists(t *testing.T) {
 	srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
 		defer r.Body.Close()
 
+		if r.URL.Path == "/repos/someone/something/contents/.github/PULL_REQUEST_TEMPLATE.md" {
+			w.WriteHeader(http.StatusNotFound)
+			return
+		}
+
 		if r.URL.Path == "/repos/someone/something/pulls" {
 			w.WriteHeader(http.StatusUnprocessableEntity)
 			r, err := os.Open("testdata/github/pull.json")
@@ -587,6 +621,11 @@ func TestOpenPullRequestBaseEmpty(t *testing.T) {
 	srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
 		defer r.Body.Close()
 
+		if r.URL.Path == "/repos/someone/something/contents/.github/PULL_REQUEST_TEMPLATE.md" {
+			w.WriteHeader(http.StatusNotFound)
+			return
+		}
+
 		if r.URL.Path == "/repos/someone/something/pulls" {
 			r, err := os.Open("testdata/github/pull.json")
 			require.NoError(t, err)