Adds Gerrit webhook support

pkg/webhook/gerrit/gerrit.go

@@ -0,0 +1,116 @@
+package gerrit
+
+import (
+	"encoding/json"
+	"errors"
+	"fmt"
+	"io"
+	"net/http"
+	"strings"
+)
+
+var (
+	ErrEventNotSpecifiedToParse = errors.New("no Event specified to parse")
+	ErrInvalidHTTPMethod = errors.New("invalid HTTP Method")
+	ErrMissingGerritEvent = errors.New("missing type field")
+	ErrMissingHubSignatureHeader = errors.New("missing X-Hub-Signature-256 Header")
+	ErrEventNotFound = errors.New("event not defined to be parsed")
+	ErrParsingPayload = errors.New("error parsing payload")
+	ErrHMACVerificationFailed = errors.New("HMAC verification failed")
+)
+
+type Event string
+
+const (
+	ChangeMergedEvent Event = "change-merged"
+)
+
+// Option is a configuration option for the webhook
+type Option func(*Webhook) error
+
+// Options is a namespace var for configuration options
+var Options = WebhookOptions{}
+
+// WebhookOptions is a namespace for configuration option methods
+type WebhookOptions struct{}
+
+// GerritWebhook instance contains all methods needed to process events
+type Webhook struct {}
+
+// New creates and returns a GerritWebhook instance
+func New(options ...Option) (*Webhook, error) {
+	hook := new(Webhook)
+	for _, opt := range options {
+		if err := opt(hook); err != nil {
+			return nil, errors.New("error applying option")
+		}
+	}
+	return hook, nil
+}
+func (hook *Webhook) Parse(r *http.Request, events ...Event) (interface{}, error) {
+	defer func() {
+		_, _ = io.Copy(io.Discard, r.Body)
+		_ = r.Body.Close()
+	}()
+
+	if len(events) == 0 {
+		return nil, ErrEventNotSpecifiedToParse
+	}
+	if r.Method != http.MethodPost {
+		return nil, ErrInvalidHTTPMethod
+	}
+
+	payload, err := io.ReadAll(r.Body)
+	if err != nil || len(payload) == 0 {
+		return nil, ErrParsingPayload
+	}
+
+	var envelope Envelope
+	err = json.Unmarshal([]byte(payload), &envelope)
+
+	if err != nil {
+		return nil, ErrParsingPayload
+	}
+
+	event := envelope.Type
+
+	if event == "" {
+		return nil, ErrMissingGerritEvent
+	}
+
+	gerritEvent := Event(event)
+
+	var found bool
+	for _, evt := range events {
+		if evt == gerritEvent {
+			found = true
+			break
+		}
+	}
+
+	// event not defined to be parsed
+	if !found {
+		return nil, ErrEventNotFound
+	}
+
+	switch gerritEvent {
+	case ChangeMergedEvent:
+		var pl ChangeMergedPayload
+		err = json.Unmarshal([]byte(payload), &pl)
+		return pl, err
+	default:
+		return nil, fmt.Errorf("unknown event %s", gerritEvent)
+	}
+
+}
+
+func ExtractRepoURL(payload ChangeMergedPayload) (string, error) {
+	// URL is in the format of https://<gerrit-host>/c/<project>/+/<change-id>
+	parts := strings.Split(payload.Change.URL, "/")
+	if len(parts) < 7 {
+		return "", fmt.Errorf("invalid URL %s", payload.Change.URL)
+	}
+
+	url := fmt.Sprintf("%s//%s/%s", parts[0], parts[2], parts[4])
+	return url, nil
+}

pkg/webhook/gerrit/schema.go

@@ -0,0 +1,65 @@
+package gerrit
+
+type Envelope struct {
+	Submitter      User      `json:"-"`
+	NewRev         string    `json:"-"`
+	PatchSet       PatchSet  `json:"-"`
+	Change         Change    `json:"-"`
+	Project        Project   `json:"-"`
+	RefName        string    `json:"-"`
+	ChangeKey      ChangeKey `json:"-"`
+	Type           string    `json:"type"`
+	EventCreatedOn int64     `json:"-"`
+}
+
+type ChangeMergedPayload struct {
+	Submitter      User      `json:"submitter"`
+	NewRev         string    `json:"newRev"`
+	PatchSet       PatchSet  `json:"patchSet"`
+	Change         Change    `json:"change"`
+	Project        Project   `json:"project"`
+	RefName        string    `json:"refName"`
+	ChangeKey      ChangeKey `json:"changeKey"`
+	Type           string    `json:"type"`
+	EventCreatedOn int64     `json:"eventCreatedOn"`
+}
+
+type User struct {
+	Name     string `json:"name"`
+	Email    string `json:"email"`
+	Username string `json:"username"`
+}
+
+type PatchSet struct {
+	Number         int64    `json:"number"`
+	Revision       string   `json:"revision"`
+	Parents        []string `json:"parents"`
+	Ref            string   `json:"ref"`
+	Uploader       User     `json:"uploader"`
+	CreatedOn      int64    `json:"createdOn"`
+	Author         User     `json:"author"`
+	Kind           string   `json:"kind"`
+	SizeInsertions int64    `json:"sizeInsertions"`
+	SizeDeletions  int64    `json:"sizeDeletions"`
+}
+
+type Change struct {
+	Project       string `json:"project"`
+	Branch        string `json:"branch"`
+	ID            string `json:"id"`
+	Number        int64  `json:"number"`
+	Subject       string `json:"subject"`
+	Owner         User   `json:"owner"`
+	URL           string `json:"url"`
+	CommitMessage string `json:"commitMessage"`
+	CreatedOn     int64  `json:"createdOn"`
+	Status        string `json:"status"`
+}
+
+type Project struct {
+	Name string `json:"name"`
+}
+
+type ChangeKey struct {
+	Key string `json:"key"`
+}

pkg/webhook/parser.go

@@ -12,6 +12,8 @@ import (
 	"github.com/go-playground/webhooks/v6/gitlab"
 	"github.com/go-playground/webhooks/v6/gogs"
 	corev1 "k8s.io/api/core/v1"
+
+	gerrit "github.com/rancher/fleet/pkg/webhook/gerrit"
 )
 
 const (
@@ -39,6 +41,9 @@ func parseWebhook(r *http.Request, secret *corev1.Secret) (any, error) {
 		return parseBitbucketServer(r, secret)
 	case r.Header.Get("X-Vss-Activityid") != "" || r.Header.Get("X-Vss-Subscriptionid") != "":
 		return parseAzureDevops(r, secret)
+	// Gerrit does not provide any discernible headers to identify the event. So we need to put it at the end.
+	case r.Header.Get("x-origin-url") != "":
+		return parseGerrit(r, secret)
 	}
 
 	return nil, nil
@@ -79,6 +84,23 @@ func parseGogs(r *http.Request, secret *corev1.Secret) (any, error) {
 	return hook.Parse(r, gogs.PushEvent)
 }
 
+func parseGerrit(r *http.Request, secret *corev1.Secret) (any, error) {
+	var hook *gerrit.Webhook
+	var err error
+
+	if secret != nil {
+		// Gerrit does not support secrets.
+	}
+
+	hook, err = gerrit.New()
+
+	if err != nil {
+		return nil, err
+	}
+
+	return hook.Parse(r, gerrit.ChangeMergedEvent)
+}
+
 func parseGithub(r *http.Request, secret *corev1.Secret) (any, error) {
 	var hook *github.Webhook
 	var err error