Add support for dockerhub rate-limiting

Signed-off-by: Jiri Vrba <jiri.vrba@firma.seznam.cz>

src/pkg/reg/adapter/dockerhub/adapter.go

@@ -21,7 +21,9 @@ import (
 	"fmt"
 	"io"
 	"net/http"
+	"strconv"
 	"strings"
+	"time"
 
 	"github.com/goharbor/harbor/src/common/utils"
 	"github.com/goharbor/harbor/src/lib/log"
@@ -124,6 +126,55 @@ func getAdapterInfo() *model.AdapterPattern {
 	return info
 }
 
+// Rate-limit aware wrapper function for client.Do()
+// - Avoids being hit by limit by pausing requests when less than 'lowMark' requests remaining.
+// - Pauses for given time when limit is hit.
+// - Allows 2 more attempts before giving up.
+// Reason: Observed (02/2024) penalty for hitting the limit is 120s, normal reset is 60s,
+// so it is better to not hit the wall.
+func (a *adapter) limitAwareDo(method string, path string, body io.Reader) (*http.Response, error) {
+	const lowMark = 8
+	var attemptsLeft = 3
+	for attemptsLeft > 0 {
+		clientResp, clientErr := a.client.Do(method, path, body)
+		if clientErr != nil {
+			return clientResp, clientErr
+		}
+		if clientResp.StatusCode != http.StatusTooManyRequests {
+			reqsLeft, err := strconv.ParseInt(clientResp.Header.Get("x-ratelimit-remaining"), 10, 64)
+			if err != nil {
+				return clientResp, clientErr
+			}
+			if reqsLeft < lowMark {
+				resetTSC, err := strconv.ParseInt(clientResp.Header.Get("x-ratelimit-reset"), 10, 64)
+				if err == nil {
+					dur := time.Until(time.Unix(resetTSC, 0))
+					log.Infof("Rate-limit exhaustion eminent, sleeping for %.1f seconds", dur.Seconds())
+					time.Sleep(dur)
+					log.Info("Sleep finished, resuming operation")
+				}
+			}
+			return clientResp, clientErr
+		}
+		var dur = time.Duration(0)
+		seconds, err := strconv.ParseInt(clientResp.Header.Get("retry-after"), 10, 64)
+		if err != nil {
+			expireTime, err := http.ParseTime(clientResp.Header.Get("retry-after"))
+			if err != nil {
+				return nil, errors.New("blocked by dockerhub rate-limit and missing retry-after header")
+			}
+			dur = time.Until(expireTime)
+		} else {
+			dur = time.Duration(seconds) * time.Second
+		}
+		log.Infof("Rate-limit exhausted, sleeping for %.1f seconds", dur.Seconds())
+		time.Sleep(dur)
+		log.Info("Sleep finished, resuming operation")
+		attemptsLeft--
+	}
+	return nil, errors.New("unable to get past dockerhub rate-limit")
+}
+
 // PrepareForPush does the prepare work that needed for pushing/uploading the resource
 // eg: create the namespace or repository
 func (a *adapter) PrepareForPush(resources []*model.Resource) error {
@@ -159,7 +210,7 @@ func (a *adapter) PrepareForPush(resources []*model.Resource) error {
 }
 
 func (a *adapter) listNamespaces() ([]string, error) {
-	resp, err := a.client.Do(http.MethodGet, listNamespacePath, nil)
+	resp, err := a.limitAwareDo(http.MethodGet, listNamespacePath, nil)
 	if err != nil {
 		return nil, err
 	}
@@ -207,7 +258,7 @@ func (a *adapter) CreateNamespace(namespace *model.Namespace) error {
 		return err
 	}
 
-	resp, err := a.client.Do(http.MethodPost, createNamespacePath, bytes.NewReader(b))
+	resp, err := a.limitAwareDo(http.MethodPost, createNamespacePath, bytes.NewReader(b))
 	if err != nil {
 		return err
 	}
@@ -228,7 +279,7 @@ func (a *adapter) CreateNamespace(namespace *model.Namespace) error {
 
 // getNamespace get namespace from DockerHub, if the namespace not found, two nil would be returned.
 func (a *adapter) getNamespace(namespace string) (*model.Namespace, error) {
-	resp, err := a.client.Do(http.MethodGet, getNamespacePath(namespace), nil)
+	resp, err := a.limitAwareDo(http.MethodGet, getNamespacePath(namespace), nil)
 	if err != nil {
 		return nil, err
 	}
@@ -389,7 +440,7 @@ func (a *adapter) DeleteManifest(repository, reference string) error {
 		return fmt.Errorf("dockerhub only support repo in format <namespace>/<name>, but got: %s", repository)
 	}
 
-	resp, err := a.client.Do(http.MethodDelete, deleteTagPath(parts[0], parts[1], reference), nil)
+	resp, err := a.limitAwareDo(http.MethodDelete, deleteTagPath(parts[0], parts[1], reference), nil)
 	if err != nil {
 		return err
 	}
@@ -410,7 +461,7 @@ func (a *adapter) DeleteManifest(repository, reference string) error {
 
 // getRepos gets a page of repos from DockerHub
 func (a *adapter) getRepos(namespace, name string, page, pageSize int) (*ReposResp, error) {
-	resp, err := a.client.Do(http.MethodGet, listReposPath(namespace, name, page, pageSize), nil)
+	resp, err := a.limitAwareDo(http.MethodGet, listReposPath(namespace, name, page, pageSize), nil)
 	if err != nil {
 		return nil, err
 	}
@@ -437,7 +488,7 @@ func (a *adapter) getRepos(namespace, name string, page, pageSize int) (*ReposRe
 
 // getTags gets a page of tags for a repo from DockerHub
 func (a *adapter) getTags(namespace, repo string, page, pageSize int) (*TagsResp, error) {
-	resp, err := a.client.Do(http.MethodGet, listTagsPath(namespace, repo, page, pageSize), nil)
+	resp, err := a.limitAwareDo(http.MethodGet, listTagsPath(namespace, repo, page, pageSize), nil)
 	if err != nil {
 		return nil, err
 	}