Add GitHub status updates to Pull Request CRD.

This adds support for the GitHub Status API
(https://developer.github.com/v3/repos/statuses/).

This accompanies tektoncd#778 and tektoncd#895 to complete initial Pull Request support
support for GitHub OAuth.

cmd/pullrequest-init/README.md

@@ -44,7 +44,16 @@ like:
             "Text": "my-label"
         }
     ],
-    "Raw": "/tmp/prtest/github/pr.json"
+    "Statuses": [
+        {
+            "Code": "success",
+            "Description": "Job succeeded.",
+            "ID": "pull-tekton-pipeline-go-coverage",
+            "URL": "https://tekton-releases.appspot.com/build/tekton-prow/pr-logs/pull/tektoncd_pipeline/895/pull-tekton-pipeline-go-coverage/1141483806818045953/"
+        },
+    ],
+    "Raw": "/tmp/prtest/github/pr.json",
+    "RawStatus": "/tmp/pr/github/status.json"
 }
 ```
 
@@ -54,6 +63,9 @@ GitHub pull requests will output these additional files:
 
 *   `$PATH/github/pr.json`: The raw GitHub payload as specified by
     https://developer.github.com/v3/pulls/#get-a-single-pull-request
+*   `$PATH/github/status.json`: The raw GitHub combined status payload as
+    specified by
+    https://developer.github.com/v3/repos/statuses/#get-the-combined-status-for-a-specific-ref
 *   `$PATH/github/comments/#.json`: Comments associated to the PR as specified
     by https://developer.github.com/v3/issues/comments/#get-a-single-comment
 
@@ -62,3 +74,18 @@ For now, these files are *read-only*.
 The binary will look for GitHub credentials in the `${GITHUBTOKEN}` environment
 variable. This should generally be specified as a secret with the field name
 `githubToken` in the `PullRequestResource` definition.
+
+### Status code conversion
+
+Tekton Status Code | GitHub Status State
+------------------ | -------------------
+success            | success
+neutral            | success
+queued             | pending
+in_progress        | pending
+failure            | failure
+unknown            | error
+error              | error
+timeout            | error
+canceled           | error
+action_required    | error

cmd/pullrequest-init/fake_github.go

@@ -35,6 +35,7 @@ type FakeGitHub struct {
 	// We need to store references to both to emulate the API properly.
 	prComments map[key][]*github.IssueComment
 	comments   map[key]*github.IssueComment
+	status     map[statusKey]map[string]*github.RepoStatus
 }
 
 // NewFakeGitHub returns a new FakeGitHub.
@@ -44,13 +45,16 @@ func NewFakeGitHub() *FakeGitHub {
 		pr:         make(map[key]*github.PullRequest),
 		prComments: make(map[key][]*github.IssueComment),
 		comments:   make(map[key]*github.IssueComment),
+		status:     make(map[statusKey]map[string]*github.RepoStatus),
 	}
 	s.HandleFunc("/repos/{owner}/{repo}/pulls/{number}", s.getPullRequest).Methods(http.MethodGet)
 	s.HandleFunc("/repos/{owner}/{repo}/issues/{number}/comments", s.getComments).Methods(http.MethodGet)
 	s.HandleFunc("/repos/{owner}/{repo}/issues/{number}/comments", s.createComment).Methods(http.MethodPost)
 	s.HandleFunc("/repos/{owner}/{repo}/issues/comments/{number}", s.updateComment).Methods(http.MethodPatch)
 	s.HandleFunc("/repos/{owner}/{repo}/issues/comments/{number}", s.deleteComment).Methods(http.MethodDelete)
 	s.HandleFunc("/repos/{owner}/{repo}/issues/{number}/labels", s.updateLabels).Methods(http.MethodPut)
+	s.HandleFunc("/repos/{owner}/{repo}/statuses/{revision}", s.createStatus).Methods(http.MethodPost)
+	s.HandleFunc("/repos/{owner}/{repo}/commits/{revision}/status", s.getStatuses).Methods(http.MethodGet)
 
 	return s
 }
@@ -230,3 +234,50 @@ func (g *FakeGitHub) updateLabels(w http.ResponseWriter, r *http.Request) {
 
 	w.WriteHeader(http.StatusOK)
 }
+
+type statusKey struct {
+	owner    string
+	repo     string
+	revision string
+}
+
+func getStatusKey(r *http.Request) statusKey {
+	return statusKey{
+		owner:    mux.Vars(r)["owner"],
+		repo:     mux.Vars(r)["repo"],
+		revision: mux.Vars(r)["revision"],
+	}
+}
+
+func (g *FakeGitHub) createStatus(w http.ResponseWriter, r *http.Request) {
+	k := getStatusKey(r)
+
+	rs := new(github.RepoStatus)
+	if err := json.NewDecoder(r.Body).Decode(rs); err != nil {
+		http.Error(w, err.Error(), http.StatusInternalServerError)
+		return
+	}
+
+	if _, ok := g.status[k]; !ok {
+		g.status[k] = make(map[string]*github.RepoStatus)
+	}
+	g.status[k][rs.GetContext()] = rs
+}
+
+func (g *FakeGitHub) getStatuses(w http.ResponseWriter, r *http.Request) {
+	k := getStatusKey(r)
+
+	s := make([]github.RepoStatus, 0, len(g.status[k]))
+	for _, v := range g.status[k] {
+		s = append(s, *v)
+	}
+
+	cs := &github.CombinedStatus{
+		TotalCount: github.Int(len(s)),
+		Statuses:   s,
+	}
+	if err := json.NewEncoder(w).Encode(cs); err != nil {
+		http.Error(w, err.Error(), http.StatusInternalServerError)
+		return
+	}
+}

cmd/pullrequest-init/fake_github_test.go

@@ -64,3 +64,38 @@ func TestFakeGitHubBadKey(t *testing.T) {
 		t.Errorf("want BadRequest, got %+v, %v", resp, err)
 	}
 }
+
+func TestFakeGitHubStatus(t *testing.T) {
+	ctx := context.Background()
+	gh := NewFakeGitHub()
+	client, close := githubClient(t, gh)
+	defer close()
+
+	sha := "tacocat"
+
+	if got, resp, err := client.Repositories.GetCombinedStatus(ctx, owner, repo, sha, nil); err != nil || resp.StatusCode != http.StatusOK || len(got.Statuses) != 0 {
+		t.Fatalf("GetCombinedStatus: wanted [], got %+v, %+v, %v", got, resp, err)
+	}
+
+	rs := &github.RepoStatus{
+		Context:     github.String("Tekton"),
+		Description: github.String("Test all the things!"),
+		State:       github.String("success"),
+		TargetURL:   github.String("https://tekton.dev"),
+	}
+	if _, _, err := client.Repositories.CreateStatus(ctx, owner, repo, sha, rs); err != nil {
+		t.Fatalf("CreateStatus: %v", err)
+	}
+
+	got, resp, err := client.Repositories.GetCombinedStatus(ctx, owner, repo, sha, nil)
+	if err != nil || resp.StatusCode != http.StatusOK {
+		t.Fatalf("GetCombinedStatus: wanted OK, got %+v, %v", resp, err)
+	}
+	want := &github.CombinedStatus{
+		TotalCount: github.Int(1),
+		Statuses:   []github.RepoStatus{*rs},
+	}
+	if diff := cmp.Diff(want, got); diff != "" {
+		t.Errorf("GetCombinedStatus: -want +got: %s", diff)
+	}
+}

cmd/pullrequest-init/github.go

@@ -18,6 +18,29 @@ import (
 	"go.uber.org/zap"
 )
 
+var (
+	toGitHub = map[StatusCode]string{
+		Unknown: "error",
+		Success: "success",
+		Failure: "failure",
+		Error:   "error",
+		// There's no analog for neutral in GitHub statuses, so default to success
+		// to make this non-blocking.
+		Neutral:        "success",
+		Queued:         "pending",
+		InProgress:     "pending",
+		Timeout:        "error",
+		Canceled:       "error",
+		ActionRequired: "error",
+	}
+	toTekton = map[string]StatusCode{
+		"success": Success,
+		"failure": Failure,
+		"error":   Error,
+		"pending": Queued,
+	}
+)
+
 // GitHubHandler handles interactions with the GitHub API.
 type GitHubHandler struct {
 	*github.Client
@@ -97,6 +120,14 @@ func (h *GitHubHandler) Download(ctx context.Context, path string) error {
 	}
 	pr := baseGitHubPullRequest(gpr)
 
+	rawStatus := filepath.Join(rawPrefix, "status.json")
+	statuses, err := h.getStatuses(ctx, pr.Head.SHA, rawStatus)
+	if err != nil {
+		return err
+	}
+	pr.RawStatus = rawStatus
+	pr.Statuses = statuses
+
 	rawPR := filepath.Join(rawPrefix, "pr.json")
 	if err := writeJSON(rawPR, gpr); err != nil {
 		return err
@@ -197,6 +228,11 @@ func (h *GitHubHandler) Upload(ctx context.Context, path string) error {
 	}
 
 	var merr error
+
+	if err := h.uploadStatuses(ctx, pr.Head.SHA, pr.Statuses); err != nil {
+		merr = multierror.Append(merr, err)
+	}
+
 	if err := h.uploadLabels(ctx, pr.Labels); err != nil {
 		merr = multierror.Append(merr, err)
 	}
@@ -297,3 +333,53 @@ func (h *GitHubHandler) createNewComments(ctx context.Context, comments []*Comme
 	}
 	return merr
 }
+
+func (h *GitHubHandler) getStatuses(ctx context.Context, sha string, path string) ([]*Status, error) {
+	resp, _, err := h.Repositories.GetCombinedStatus(ctx, h.owner, h.repo, sha, nil)
+	if err != nil {
+		return nil, err
+	}
+	if err := writeJSON(path, resp); err != nil {
+		return nil, err
+	}
+
+	statuses := make([]*Status, 0, len(resp.Statuses))
+	for _, s := range resp.Statuses {
+		code, ok := toTekton[s.GetState()]
+		if !ok {
+			return nil, fmt.Errorf("unknown GitHub status state: %s", s.GetState())
+		}
+		statuses = append(statuses, &Status{
+			ID:          s.GetContext(),
+			Code:        code,
+			Description: s.GetDescription(),
+			URL:         s.GetTargetURL(),
+		})
+	}
+	return statuses, nil
+}
+
+func (h *GitHubHandler) uploadStatuses(ctx context.Context, sha string, statuses []*Status) error {
+	var merr error
+
+	for _, s := range statuses {
+		state, ok := toGitHub[s.Code]
+		if !ok {
+			merr = multierror.Append(merr, fmt.Errorf("unknown status code %s", s.Code))
+			continue
+		}
+
+		rs := &github.RepoStatus{
+			Context:     github.String(s.ID),
+			State:       github.String(state),
+			Description: github.String(s.Description),
+			TargetURL:   github.String(s.URL),
+		}
+		if _, _, err := h.Client.Repositories.CreateStatus(ctx, h.owner, h.repo, sha, rs); err != nil {
+			merr = multierror.Append(merr, err)
+			continue
+		}
+	}
+
+	return merr
+}