Add support for Github Checks (#110)

Currently only Github status checks are supported. This change adds
support for the newer Github Checks API.

I replaced the CheckSuite handler with a CheckRun one. CheckSuiteEvents
are only sent once per ref, whereas a CheckRun can change after a ref is
created.

This change requires updated permissions to allow us to lookup Checks
for specific refs and to listen to CheckRunEvents.

README.md

@@ -274,6 +274,7 @@ Bulldozer requires the following permissions as a GitHub app:
 | Permission | Access | Reason |
 | ---------- | ------ | ------ |
 | Repository administration | Read-only | Determine required status checks |
+| Checks | Read-only | Read checks for ref |
 | Repository contents | Read & write | Read configuration, perform merges |
 | Issues | Read & write | Read comments, close linked issues |
 | Repository metadata | Read-only | Basic repository data |
@@ -282,6 +283,7 @@ Bulldozer requires the following permissions as a GitHub app:
 
 It should be subscribed to the following events:
 
+* Check run
 * Commit comment
 * Pull request
 * Status

pull/github_context.go

@@ -224,6 +224,25 @@ func (ghc *GithubContext) CurrentSuccessStatuses(ctx context.Context) ([]string,
 			opts.Page = res.NextPage
 		}
 
+		checkOpts := &github.ListCheckRunsOptions{ListOptions: github.ListOptions{PerPage: 100}}
+		for {
+			checkRuns, res, err := ghc.client.Checks.ListCheckRunsForRef(ctx, ghc.owner, ghc.repo, ghc.pr.GetHead().GetSHA(), checkOpts)
+			if err != nil {
+				return ghc.successStatuses, errors.Wrapf(err, "cannot get check runs for SHA %s on %s", ghc.pr.GetHead().GetSHA(), ghc.Locator())
+			}
+
+			for _, s := range checkRuns.CheckRuns {
+				if s.GetConclusion() == "success" {
+					successStatuses = append(successStatuses, s.GetName())
+				}
+			}
+
+			if res.NextPage == 0 {
+				break
+			}
+			checkOpts.Page = res.NextPage
+		}
+
 		ghc.successStatuses = successStatuses
 	}
 

server/handler/check_run.go

@@ -0,0 +1,85 @@
+// Copyright 2018 Palantir Technologies, 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 handler
+
+import (
+	"context"
+	"encoding/json"
+
+	"github.com/google/go-github/github"
+	"github.com/palantir/go-githubapp/githubapp"
+	"github.com/pkg/errors"
+
+	"github.com/palantir/bulldozer/pull"
+)
+
+type CheckRun struct {
+	Base
+}
+
+func (h *CheckRun) Handles() []string {
+	return []string{"check_run"}
+}
+
+func (h *CheckRun) Handle(ctx context.Context, eventType, deliveryID string, payload []byte) error {
+	var event github.CheckRunEvent
+
+	if err := json.Unmarshal(payload, &event); err != nil {
+		return errors.Wrap(err, "failed to parse check_run event payload")
+	}
+
+	repo := event.GetRepo()
+	installationID := githubapp.GetInstallationIDFromEvent(&event)
+
+	ctx, logger := githubapp.PrepareRepoContext(ctx, installationID, repo)
+
+	if event.GetAction() != "completed" {
+		logger.Debug().Msgf("Doing nothing since check_run action was %q instead of 'completed'", event.GetAction())
+		return nil
+	}
+
+	client, err := h.ClientCreator.NewInstallationClient(installationID)
+	if err != nil {
+		return errors.Wrap(err, "failed to instantiate github client")
+	}
+
+	prs := event.GetCheckRun().PullRequests
+	if len(prs) == 0 {
+		logger.Debug().Msg("Doing nothing since status change event affects no open pull requests")
+		return nil
+	}
+
+	for _, pr := range prs {
+		// The PR included in the CheckRun response is very slim on information.
+		// It does not contain the owner information or label information we
+		// need to process the pull request.
+
+		fullPR, _, err := client.PullRequests.Get(ctx, repo.GetOwner().GetLogin(), repo.GetName(), pr.GetNumber())
+		if err != nil {
+			return errors.Wrapf(err, "failed to fetch PR number %q for CheckRun", pr.GetNumber())
+		}
+		pullCtx := pull.NewGithubContext(client, fullPR)
+
+		logger := logger.With().Int(githubapp.LogKeyPRNum, pr.GetNumber()).Logger()
+		if err := h.ProcessPullRequest(logger.WithContext(ctx), pullCtx, client, pr); err != nil {
+			logger.Error().Err(errors.WithStack(err)).Msg("Error processing pull request")
+		}
+	}
+
+	return nil
+}
+
+// type assertion
+var _ githubapp.EventHandler = &CheckRun{}

server/server.go

@@ -69,6 +69,7 @@ func New(c *Config) (*Server, error) {
 	}
 
 	webhookHandler := githubapp.NewDefaultEventDispatcher(c.Github,
+		&handler.CheckRun{Base: baseHandler},
 		&handler.IssueComment{Base: baseHandler},
 		&handler.PullRequest{Base: baseHandler},
 		&handler.PullRequestReview{Base: baseHandler},