1 files changed, 144 insertions, 0 deletions
diff --git a/tools/gerrit-hook/gerrit.go b/tools/gerrit-hook/gerrit.go
new file mode 100644
index 0000000..6a23527
--- /dev/null
+++ b/tools/gerrit-hook/gerrit.go
@@ -0,0 +1,144 @@
+package main
+
+import (
+	"bytes"
+	"context"
+	"encoding/json"
+	"flag"
+	"fmt"
+	"io/ioutil"
+	"log"
+	"log/syslog"
+	"net/http"
+	"os"
+	"regexp"
+	"strconv"
+	"time"
+)
+
+// Regular expression to extract change ID out of a URL
+var changeIdRegexp = regexp.MustCompile(`^.*/(\d+)$`)
+
+func gerritHookMain(cfg *config, log *syslog.Writer, trigger *buildTrigger) {
+	if trigger == nil {
+		os.Exit(0)
+	}
+
+	err := triggerBuild(cfg, log, trigger)
+	if err != nil {
+		log.Err(fmt.Sprintf("failed to trigger Buildkite build: %s", err))
+		os.Exit(1)
+	}
+}
+
+type reviewInput struct {
+	Message                        string         `json:"message"`
+	Labels                         map[string]int `json:"labels,omitempty"`
+	OmitDuplicateComments          bool           `json:"omit_duplicate_comments"`
+	IgnoreDefaultAttentionSetRules bool           `json:"ignore_default_attention_set_rules"`
+	Tag                            string         `json:"tag"`
+	Notify                         string         `json:"notify,omitempty"`
+}
+
+type buildTrigger struct {
+	project             string
+	change              string
+	kind                string
+	changeUrl           string
+	changeOwner         string
+	changeOwnerUserName string
+	branch              string
+	topic               string
+	uploader            string
+	uploaderUserName    string
+	commit              string
+	patchset            string
+	changeId            string
+	ref                 string
+}
+
+// https://gerrit.googlesource.com/plugins/hooks/+/HEAD/src/main/resources/Documentation/hooks.md#patchset_created
+func triggerForPatchsetCreated() (*buildTrigger, error) {
+	var trigger buildTrigger
+
+	flag.StringVar(&trigger.project, "project", "", "Gerrit project")
+	flag.StringVar(&trigger.change, "change", "", "Gerrit change")
+	flag.StringVar(&trigger.kind, "kind", "", "Gerrit kind")
+	flag.StringVar(&trigger.changeUrl, "change-url", "", "Gerrit URL for the change")
+	flag.StringVar(&trigger.changeOwner, "change-owner", "", "Gerrit owner")
+	flag.StringVar(&trigger.changeOwnerUserName, "change-owner-username", "", "Gerrit username")
+	flag.StringVar(&trigger.branch, "branch", "", "name of the branch")
+	flag.StringVar(&trigger.topic, "topic", "", "name of the topic")
+	flag.StringVar(&trigger.uploader, "uploader", "", "name ofthe uploader")
+	flag.StringVar(&trigger.uploaderUserName, "uploader-username", "", "")
+	flag.StringVar(&trigger.commit, "commit", "", "")
+	flag.StringVar(&trigger.patchset, "patchset", "", "")
+
+	flag.Parse()
+
+	// for now we only care about the project named `world' and the
+	// branch named 'main'
+	if trigger.project != "world" || trigger.branch != "main" {
+		return nil, nil
+	}
+
+	// We only care about patchset that are actually modifying the
+	// code. See
+	// https://gerrit-review.googlesource.com/Documentation/config-labels.html
+	if trigger.kind == "NO_CODE_CHANGE" || trigger.kind == "NO_CHANGE" {
+		return nil, nil
+	}
+
+	// extract the changeId from the URL
+	matches := changeIdRegexp.FindStringSubmatch(trigger.changeUrl)
+	trigger.changeId = matches[1]
+
+	// build the ref
+	changeId, _ := strconv.Atoi(trigger.changeId)
+	trigger.ref = fmt.Sprintf(
+		"refs/changes/%02d/%s/%s",
+		changeId%100, trigger.changeId, trigger.patchset,
+	)
+
+	return &trigger, nil
+}
+
+// after triggering a build with buildKite, we update gerrit to add a
+// comment that links to the build.
+func updateGerrit(cfg *config, review reviewInput, changeId string, patchSet string) {
+	body, err := json.Marshal(review)
+	if err != nil {
+		log.Fatal(fmt.Sprintf("failed to marshal gerrit update: %v", err))
+		os.Exit(1)
+	}
+
+	reader := ioutil.NopCloser(bytes.NewReader(body))
+	url := fmt.Sprintf("%s/a/changes/%s/revisions/%s/review", cfg.GerritUrl, changeId, patchSet)
+	req, err := http.NewRequest("POST", url, reader)
+	if err != nil {
+		fmt.Fprintf(os.Stderr, "failed to create an HTTP request: %v", err)
+		os.Exit(1)
+	}
+
+	req.SetBasicAuth(cfg.GerritUser, cfg.GerritPassword)
+	req.Header.Add("Content-Type", "application/json")
+
+	// Let's budget this to 10 seconds maximum, this should be more
+	// than enough to add a comment to gerrit.
+	ctx, cancel := context.WithTimeout(context.Background(), 10*time.Second)
+	defer cancel()
+
+	resp, err := http.DefaultClient.Do(req.WithContext(ctx))
+	if err != nil {
+		fmt.Fprintf(os.Stderr, "failed to send gerrit request: %v", err)
+		os.Exit(1)
+	}
+	defer resp.Body.Close()
+
+	if resp.StatusCode != http.StatusOK {
+		respBody, _ := ioutil.ReadAll(resp.Body)
+		fmt.Fprintf(os.Stderr, "failed to update gerrit: %s: %s ", respBody, resp.Status)
+	} else {
+		fmt.Printf("added link to CI build to %s", patchSet)
+	}
+}