feat(docker): show docker pull rate limits (#4666)

* feat(dockerhub): introduce local status endpoint

* feat(proxy): rewrite request with dockerhub credentials

* feat(endpoint): check env type

* feat(endpoint): check for local endpoint

* feat(docker): introduce client side service to get limits

* feat(container): add info about rate limits in container

* feat(dockerhub): load rate limits just for specific endpoints

* feat(images): show specific dockerhub messages for admin

* feat(service-create): show docker rate limits

* feat(service-edit): show rate limit messages

* fix(images): fix loading of page

* refactor(images): move rate limits check to container

* feat(kubernetes): proxy agent requests

* feat(kubernetes/apps): show pull limits in application creation

* refactor(image-registry): move warning to end of field

* fix(image-registry): show right message for admin

* fix(images): silently fail when loading rate limits

* fix(kube/apps): use new rate limits comp

* fix(images): move rate warning to end

* fix(registry): move search to right place

* fix(service): remove service warning

* fix(endpoints): check if kube endpoint is local

api/http/handler/endpoints/endpoint_dockerhub_status.go

@@ -0,0 +1,140 @@
+package endpoints
+
+import (
+	"encoding/json"
+	"errors"
+	"fmt"
+	"net/http"
+	"strconv"
+	"strings"
+
+	httperror "github.com/portainer/libhttp/error"
+	"github.com/portainer/libhttp/request"
+	"github.com/portainer/libhttp/response"
+	portainer "github.com/portainer/portainer/api"
+	bolterrors "github.com/portainer/portainer/api/bolt/errors"
+	"github.com/portainer/portainer/api/http/client"
+	"github.com/portainer/portainer/api/internal/endpointutils"
+)
+
+type dockerhubStatusResponse struct {
+	Remaining int `json:"remaining"`
+	Limit     int `json:"limit"`
+}
+
+// GET request on /api/endpoints/{id}/dockerhub/status
+func (handler *Handler) endpointDockerhubStatus(w http.ResponseWriter, r *http.Request) *httperror.HandlerError {
+	endpointID, err := request.RetrieveNumericRouteVariableValue(r, "id")
+	if err != nil {
+		return &httperror.HandlerError{http.StatusBadRequest, "Invalid endpoint identifier route variable", err}
+	}
+
+	endpoint, err := handler.DataStore.Endpoint().Endpoint(portainer.EndpointID(endpointID))
+	if err == bolterrors.ErrObjectNotFound {
+		return &httperror.HandlerError{http.StatusNotFound, "Unable to find an endpoint with the specified identifier inside the database", err}
+	} else if err != nil {
+		return &httperror.HandlerError{http.StatusInternalServerError, "Unable to find an endpoint with the specified identifier inside the database", err}
+	}
+
+	if !endpointutils.IsLocalEndpoint(endpoint) {
+		return &httperror.HandlerError{http.StatusBadRequest, "Invalid environment type", errors.New("Invalid environment type")}
+	}
+
+	dockerhub, err := handler.DataStore.DockerHub().DockerHub()
+	if err != nil {
+		return &httperror.HandlerError{http.StatusInternalServerError, "Unable to retrieve DockerHub details from the database", err}
+	}
+
+	httpClient := client.NewHTTPClient()
+	token, err := getDockerHubToken(httpClient, dockerhub)
+	if err != nil {
+		return &httperror.HandlerError{http.StatusInternalServerError, "Unable to retrieve DockerHub token from DockerHub", err}
+	}
+
+	resp, err := getDockerHubLimits(httpClient, token)
+	if err != nil {
+		return &httperror.HandlerError{http.StatusInternalServerError, "Unable to retrieve DockerHub rate limits from DockerHub", err}
+	}
+
+	return response.JSON(w, resp)
+}
+
+func getDockerHubToken(httpClient *client.HTTPClient, dockerhub *portainer.DockerHub) (string, error) {
+	type dockerhubTokenResponse struct {
+		Token string `json:"token"`
+	}
+
+	requestURL := "https://auth.docker.io/token?service=registry.docker.io&scope=repository:ratelimitpreview/test:pull"
+
+	req, err := http.NewRequest(http.MethodGet, requestURL, nil)
+	if err != nil {
+		return "", err
+	}
+
+	if dockerhub.Authentication {
+		req.SetBasicAuth(dockerhub.Username, dockerhub.Password)
+	}
+
+	resp, err := httpClient.Do(req)
+	if err != nil {
+		return "", err
+	}
+	defer resp.Body.Close()
+
+	if resp.StatusCode != http.StatusOK {
+		return "", errors.New("failed fetching dockerhub token")
+	}
+
+	var data dockerhubTokenResponse
+	err = json.NewDecoder(resp.Body).Decode(&data)
+	if err != nil {
+		return "", err
+	}
+
+	return data.Token, nil
+}
+
+func getDockerHubLimits(httpClient *client.HTTPClient, token string) (*dockerhubStatusResponse, error) {
+
+	requestURL := "https://registry-1.docker.io/v2/ratelimitpreview/test/manifests/latest"
+
+	req, err := http.NewRequest(http.MethodHead, requestURL, nil)
+	if err != nil {
+		return nil, err
+	}
+
+	req.Header.Add("Authorization", fmt.Sprintf("Bearer %s", token))
+
+	resp, err := httpClient.Do(req)
+	if err != nil {
+		return nil, err
+	}
+	defer resp.Body.Close()
+
+	if resp.StatusCode != http.StatusOK {
+		return nil, errors.New("failed fetching dockerhub limits")
+	}
+
+	rateLimit, err := parseRateLimitHeader(resp.Header, "RateLimit-Limit")
+	rateLimitRemaining, err := parseRateLimitHeader(resp.Header, "RateLimit-Remaining")
+
+	return &dockerhubStatusResponse{
+		Limit:     rateLimit,
+		Remaining: rateLimitRemaining,
+	}, nil
+}
+
+func parseRateLimitHeader(headers http.Header, headerKey string) (int, error) {
+	headerValue := headers.Get(headerKey)
+	if headerValue == "" {
+		return 0, fmt.Errorf("Missing %s header", headerKey)
+	}
+
+	matches := strings.Split(headerValue, ";")
+	value, err := strconv.Atoi(matches[0])
+	if err != nil {
+		return 0, err
+	}
+
+	return value, nil
+}