Retry get pull request calls to github

server/events/vcs/github_client.go

@@ -17,6 +17,7 @@ import (
 	"context"
 	"fmt"
 	"strings"
+	"time"
 
 	"github.com/runatlantis/atlantis/server/events/models"
 	"github.com/runatlantis/atlantis/server/events/vcs/common"
@@ -273,7 +274,25 @@ func (g *GithubClient) PullIsMergeable(repo models.Repo, pull models.PullRequest
 
 // GetPullRequest returns the pull request.
 func (g *GithubClient) GetPullRequest(repo models.Repo, num int) (*github.PullRequest, error) {
-	pull, _, err := g.client.PullRequests.Get(g.ctx, repo.Owner, repo.Name, num)
+	var err error
+	var pull *github.PullRequest
+
+	// GitHub has started to return 404's here (#1019) even after they send the webhook.
+	// They've got some eventual consistency issues going on so we're just going
+	// to retry up to 3 times with a 1s sleep.
+	numRetries := 3
+	retryDelay := 1 * time.Second
+	for i := 0; i < numRetries; i++ {
+		pull, _, err = g.client.PullRequests.Get(g.ctx, repo.Owner, repo.Name, num)
+		if err == nil {
+			return pull, nil
+		}
+		ghErr, ok := err.(*github.ErrorResponse)
+		if !ok || ghErr.Response.StatusCode != 404 {
+			return pull, err
+		}
+		time.Sleep(retryDelay)
+	}
 	return pull, err
 }
 

server/events/vcs/github_client_test.go

@@ -852,3 +852,48 @@ func TestGithubClient_SplitComments(t *testing.T) {
 	Assert(t, strings.Contains(firstSplit, models.PlanCommand.String()), fmt.Sprintf("comment should contain the command name but was %q", firstSplit))
 	Assert(t, strings.Contains(secondSplit, "continued from previous comment"), fmt.Sprintf("comment should contain no reference to the command name but was %q", secondSplit))
 }
+
+// Test that we retry the get pull request call if it 404s.
+func TestGithubClient_Retry404(t *testing.T) {
+	var numCalls = 0
+
+	testServer := httptest.NewTLSServer(
+		http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+
+			switch r.Method + " " + r.RequestURI {
+			case "GET /api/v3/repos/runatlantis/atlantis/pulls/1":
+				defer r.Body.Close() // nolint: errcheck
+				numCalls++
+				if numCalls < 3 {
+					w.WriteHeader(404)
+				} else {
+					w.WriteHeader(200)
+				}
+				return
+			default:
+				t.Errorf("got unexpected request at %q", r.RequestURI)
+				http.Error(w, "not found", http.StatusNotFound)
+				return
+			}
+		}))
+
+	testServerURL, err := url.Parse(testServer.URL)
+	Ok(t, err)
+	client, err := vcs.NewGithubClient(testServerURL.Host, &vcs.GithubUserCredentials{"user", "pass"}, nil)
+	Ok(t, err)
+	defer disableSSLVerification()()
+	repo := models.Repo{
+		FullName:          "runatlantis/atlantis",
+		Owner:             "runatlantis",
+		Name:              "atlantis",
+		CloneURL:          "",
+		SanitizedCloneURL: "",
+		VCSHost: models.VCSHost{
+			Type:     models.Github,
+			Hostname: "github.com",
+		},
+	}
+	_, err = client.GetPullRequest(repo, 1)
+	Ok(t, err)
+	Equals(t, 3, numCalls)
+}