feat: Adding github rate limit metrics exposure

Signed-off-by: Vincent Boutour <[email protected]>

cmd/ketchup/api.go

@@ -96,7 +96,8 @@ func main() {
 	authServiceApp, authMiddlewareApp := initAuth(ketchupDb)
 
 	userServiceApp := userService.New(userStore.New(ketchupDb), authServiceApp)
-	repositoryServiceApp := repositoryService.New(repositoryStore.New(ketchupDb), github.New(githubConfig), helm.New())
+	githubApp := github.New(githubConfig)
+	repositoryServiceApp := repositoryService.New(repositoryStore.New(ketchupDb), githubApp, helm.New())
 	ketchupServiceApp := ketchupService.New(ketchupStore.New(ketchupDb), repositoryServiceApp)
 
 	mailerApp, err := mailer.New(mailerConfig)
@@ -129,6 +130,7 @@ func main() {
 	})
 
 	go ketchupApp.Start(healthApp.Done())
+	go githubApp.Start(prometheusApp.Registerer(), healthApp.Done())
 	if schedulerApp != nil {
 		go schedulerApp.Start(healthApp.Done())
 	}

pkg/github/github.go

@@ -9,11 +9,13 @@ import (
 	"strings"
 	"time"
 
+	"github.com/ViBiOh/httputils/v4/pkg/cron"
 	"github.com/ViBiOh/httputils/v4/pkg/flags"
 	"github.com/ViBiOh/httputils/v4/pkg/logger"
 	"github.com/ViBiOh/httputils/v4/pkg/request"
 	"github.com/ViBiOh/ketchup/pkg/model"
 	"github.com/ViBiOh/ketchup/pkg/semver"
+	"github.com/prometheus/client_golang/prometheus"
 )
 
 var (
@@ -25,8 +27,19 @@ type Tag struct {
 	Name string `json:"name"`
 }
 
+// RateLimit describes a rate limit on given ressource
+type RateLimit struct {
+	Remaining uint64 `json:"remaining"`
+}
+
+// RateLimitResponse describes the rate_limit response
+type RateLimitResponse struct {
+	Resources map[string]RateLimit `json:"resources"`
+}
+
 // App of package
 type App interface {
+	Start(prometheus.Registerer, <-chan struct{})
 	LatestVersions(string, []string) (map[string]semver.Version, error)
 }
 
@@ -63,6 +76,26 @@ func (a app) newClient() *request.Request {
 	})
 }
 
+func (a app) Start(registerer prometheus.Registerer, done <-chan struct{}) {
+	metrics := prometheus.NewGauge(prometheus.GaugeOpts{
+		Namespace: "ketchup",
+		Name:      "github_rate_limit_remainings",
+	})
+	registerer.MustRegister(metrics)
+
+	cron.New().Now().Each(time.Minute).OnError(func(err error) {
+		logger.Error("unable to get rate limit metrics: %s", err)
+	}).Start(func(_ time.Time) error {
+		value, err := a.getRateLimit()
+		if err != nil {
+			return err
+		}
+
+		metrics.Set(float64(value))
+		return nil
+	}, done)
+}
+
 func (a app) LatestVersions(repository string, patterns []string) (map[string]semver.Version, error) {
 	versions, compiledPatterns, err := model.PreparePatternMatching(patterns)
 	if err != nil {
@@ -79,12 +112,12 @@ func (a app) LatestVersions(repository string, patterns []string) (map[string]se
 
 		payload, err := request.ReadBodyResponse(resp)
 		if err != nil {
-			return nil, fmt.Errorf("unable to read page %d tags body `%s`: %s", page, payload, err)
+			return nil, fmt.Errorf("unable to read page %d tags body: %s", page, err)
 		}
 
 		var tags []Tag
 		if err := json.Unmarshal(payload, &tags); err != nil {
-			return nil, fmt.Errorf("unable to parse page %d tags body: %s", page, err)
+			return nil, fmt.Errorf("unable to parse page %d tags body `%s`: %s", page, payload, err)
 		}
 
 		for _, tag := range tags {
@@ -106,6 +139,25 @@ func (a app) LatestVersions(repository string, patterns []string) (map[string]se
 	return versions, nil
 }
 
+func (a app) getRateLimit() (uint64, error) {
+	resp, err := a.newClient().Get(fmt.Sprintf("%s/rate_limit", apiURL)).Send(context.Background(), nil)
+	if err != nil {
+		return 0, fmt.Errorf("unable to get rate limit: %s", err)
+	}
+
+	payload, err := request.ReadBodyResponse(resp)
+	if err != nil {
+		return 0, fmt.Errorf("unable to read rate limit body `%s`: %s", payload, err)
+	}
+
+	var rateLimits RateLimitResponse
+	if err := json.Unmarshal(payload, &rateLimits); err != nil {
+		return 0, fmt.Errorf("unable to parse rate limit response body `%s`: %s", payload, err)
+	}
+
+	return rateLimits.Resources["core"].Remaining, nil
+}
+
 func hasNext(resp *http.Response) bool {
 	for _, value := range resp.Header.Values("Link") {
 		if strings.Contains(value, `rel="next"`) {

pkg/github/githubtest/githubtest.go

@@ -3,6 +3,7 @@ package githubtest
 import (
 	"github.com/ViBiOh/ketchup/pkg/github"
 	"github.com/ViBiOh/ketchup/pkg/semver"
+	"github.com/prometheus/client_golang/prometheus"
 )
 
 var _ github.App = &App{}
@@ -30,3 +31,7 @@ func (a *App) SetLatestVersions(latestVersions map[string]semver.Version, err er
 func (a App) LatestVersions(_ string, _ []string) (map[string]semver.Version, error) {
 	return a.latestVersions, a.latestVersionsErr
 }
+
+// Start mock
+func (a App) Start(_ prometheus.Registerer, _ <-chan struct{}) {
+}