Make merge gatekeeper more resilient

README.md

@@ -16,7 +16,7 @@ At UPSIDER, we have a few internal repositories set up with a monorepo structure
 
 We are looking to add a few more features, such as extra signoff from non-coder, label based check, etc.
 
-<sup><sub>NOTE:  
+<sup><sub>NOTE:
 <sup>(\*1)</sup> There are some other hacks, such as using an empty job with the same name to override the status, but those solutions do not provide the flexible control we are after.</sub></sup>
 
 <!-- == imptr: background / end == -->
@@ -85,6 +85,7 @@ There are some customisation available for Merge Gatekeeper.
 | `token`    | `GITHUB_TOKEN` or Personal Access Token with `repo` scope                                                                                                                                                                                                                                            |   Yes    |
 | `self`     | The name of Merge Gatekeeper job, and defaults to `merge-gatekeeper`. This is used to check other job status, and do not check Merge Gatekeeper itself. If you updated the GitHub Action job name from `merge-gatekeeper` to something else, you would need to specify the new name with this value. |          |
 | `interval` | Check interval to recheck the job status. Default is set to 5 (sec).                                                                                                                                                                                                                                 |          |
+| `github-client-retry` | Retry the request if the GitHub client returns 5xx error. Default is set to 0.                                                                                                                                                                                                                                 |          |
 | `timeout`  | Timeout setup to give up further check. Default is set to 600 (sec).                                                                                                                                                                                                                                 |          |
 | `ignored`  | Jobs to ignore regardless of their statuses. Defined as a comma-separated list.                                                                                                                                                                                                                      |          |
 | `ref`      | Git ref to check out. This falls back to the HEAD for given PR, but can be set to any ref.                                                                                                                                                                                                           |          |

action.yml

@@ -15,6 +15,10 @@ inputs:
     description: "set validate interval second (default 5)"
     required: false
     default: "5"
+  github-client-retry:
+    description: "set retry count for GitHub client (default 0)"
+    required: false
+    default: "0"
   timeout:
     description: "set validate timeout second (default 600)"
     required: false
@@ -35,6 +39,7 @@ runs:
     - "--token=${{ inputs.token }}"
     - "--self=${{ inputs.self }}"
     - "--interval=${{ inputs.interval }}"
+    - "--github-client-retry=${{ inputs.github-client-retry }}"
     - "--ref=${{ inputs.ref }}"
     - "--timeout=${{ inputs.timeout }}"
     - "--ignored=${{ inputs.ignored }}"

go.sum

@@ -115,11 +115,9 @@ github.com/google/go-cmp v0.5.1/go.mod h1:v8dTdLbMG2kIc/vJvl+f65V22dbkXbowE6jgT/
 github.com/google/go-cmp v0.5.2/go.mod h1:v8dTdLbMG2kIc/vJvl+f65V22dbkXbowE6jgT/gNBxE=
 github.com/google/go-cmp v0.5.3/go.mod h1:v8dTdLbMG2kIc/vJvl+f65V22dbkXbowE6jgT/gNBxE=
 github.com/google/go-cmp v0.5.4/go.mod h1:v8dTdLbMG2kIc/vJvl+f65V22dbkXbowE6jgT/gNBxE=
-github.com/google/go-cmp v0.5.5 h1:Khx7svrCpmxxtHBq5j2mp/xVjsi8hQMfNLvJFAlrGgU=
 github.com/google/go-cmp v0.5.5/go.mod h1:v8dTdLbMG2kIc/vJvl+f65V22dbkXbowE6jgT/gNBxE=
+github.com/google/go-cmp v0.5.6 h1:BKbKCqvP6I+rmFHt06ZmyQtvB8xAkWdhFyr0ZUNZcxQ=
 github.com/google/go-cmp v0.5.6/go.mod h1:v8dTdLbMG2kIc/vJvl+f65V22dbkXbowE6jgT/gNBxE=
-github.com/google/go-github v17.0.0+incompatible h1:N0LgJ1j65A7kfXrZnUDaYCs/Sf4rEjNlfyDHW9dolSY=
-github.com/google/go-github v17.0.0+incompatible/go.mod h1:zLgOLi98H3fifZn+44m+umXrS52loVEgC2AApnigrVQ=
 github.com/google/go-github/v38 v38.1.0 h1:C6h1FkaITcBFK7gAmq4eFzt6gbhEhk7L5z6R3Uva+po=
 github.com/google/go-github/v38 v38.1.0/go.mod h1:cStvrz/7nFr0FoENgG6GLbp53WaelXucT+BBz/3VKx4=
 github.com/google/go-querystring v1.0.0/go.mod h1:odCYkC5MyYFN7vkCjXpyrEuKhc/BUO6wN/zVPAxq5ck=

internal/cli/validate.go

@@ -3,6 +3,7 @@ package cli
 import (
 	"context"
 	"fmt"
+	"net/http"
 	"os"
 	"strings"
 	"time"
@@ -25,6 +26,7 @@ var (
 	validateInvalSecond uint
 	selfJobName         string
 	ignoredJobs         string
+	githubClientRetry   int
 )
 
 func validateCmd() *cobra.Command {
@@ -45,7 +47,12 @@ func validateCmd() *cobra.Command {
 				return fmt.Errorf("github owner or repository is empty. owner: %s, repository: %s", owner, repo)
 			}
 
-			statusValidator, err := status.CreateValidator(github.NewClient(ctx, ghToken),
+			t := http.DefaultTransport
+			if githubClientRetry > 0 {
+				t = github.NewRetryTransport(githubClientRetry)
+			}
+			statusValidator, err := status.CreateValidator(
+				github.NewClient(ctx, ghToken, github.WithTransport(t)),
 				status.WithSelfJob(selfJobName),
 				status.WithGitHubOwnerAndRepo(owner, repo),
 				status.WithGitHubRef(ghRef),
@@ -72,6 +79,8 @@ func validateCmd() *cobra.Command {
 
 	cmd.PersistentFlags().StringVarP(&ignoredJobs, "ignored", "i", "", "set ignored jobs (comma-separated list)")
 
+	cmd.PersistentFlags().IntVar(&githubClientRetry, "github-client-retry", 0, "set retry count for GitHub client")
+
 	return cmd
 }
 

internal/github/github.go

@@ -2,6 +2,7 @@ package github
 
 import (
 	"context"
+	"net/http"
 
 	"github.com/google/go-github/v38/github"
 	"golang.org/x/oauth2"
@@ -25,17 +26,40 @@ type Client interface {
 	ListCheckRunsForRef(ctx context.Context, owner, repo, ref string, opts *ListCheckRunsOptions) (*ListCheckRunsResults, *Response, error)
 }
 
+type clientConfigOption func(*clientConfig)
+
 type client struct {
 	ghc *github.Client
 }
 
-func NewClient(ctx context.Context, token string) Client {
+type clientConfig struct {
+	transport http.RoundTripper
+}
+
+func WithTransport(transport http.RoundTripper) clientConfigOption {
+	return func(c *clientConfig) {
+		c.transport = transport
+	}
+}
+
+func NewClient(ctx context.Context, token string, opts ...clientConfigOption) Client {
+	clientConfig := &clientConfig{}
+
+	for _, opt := range opts {
+		opt(clientConfig)
+	}
+
 	return &client{
-		ghc: github.NewClient(oauth2.NewClient(ctx, oauth2.StaticTokenSource(
-			&oauth2.Token{
-				AccessToken: token,
+		ghc: github.NewClient(&http.Client{
+			Transport: &oauth2.Transport{
+				Base: clientConfig.transport,
+				Source: oauth2.ReuseTokenSource(nil, oauth2.StaticTokenSource(
+					&oauth2.Token{
+						AccessToken: token,
+					},
+				)),
 			},
-		))),
+		}),
 	}
 }
 

internal/github/retry_roundtripper.go

@@ -0,0 +1,48 @@
+package github
+
+import (
+	"log"
+	"math"
+	"net/http"
+	"time"
+)
+
+type RetryTransport struct {
+	next    http.RoundTripper
+	Retries int
+	log     log.Logger
+}
+
+func NewRetryTransport(retry int) *RetryTransport {
+	return &RetryTransport{
+		next:    http.DefaultTransport,
+		Retries: retry,
+	}
+}
+
+func (t *RetryTransport) RoundTrip(req *http.Request) (*http.Response, error) {
+	var (
+		resp *http.Response
+		err  error
+	)
+
+	for i := 0; i <= t.Retries; i++ {
+		resp, err = t.next.RoundTrip(req)
+		if err != nil {
+			return resp, err
+		}
+
+		if resp.StatusCode >= 500 && resp.StatusCode < 600 {
+			log.Printf("Retrying request due to status code: %d\n", resp.StatusCode)
+			delay := time.Duration(math.Pow(2, float64(i))) * time.Second
+			time.Sleep(delay)
+
+			resp.Body.Close()
+			continue
+		}
+
+		break
+	}
+
+	return resp, err
+}