feat: allow HEAD on :repo/charts/:filename endpoint

Signed-off-by: Dmytro Bainak <dmytroba@salt.security>

Author: dmytroba-salt

README.md

@@ -28,6 +28,8 @@ Powered by some great Go technology:
 - `GET /index.yaml` - retrieved when you run `helm repo add chartmuseum http://localhost:8080/`
 - `GET /charts/mychart-0.1.0.tgz` - retrieved when you run `helm install chartmuseum/mychart`
 - `GET /charts/mychart-0.1.0.tgz.prov` - retrieved when you run `helm install` with the `--verify` flag
+- `HEAD` requests for the above routes are also supported; they are **not** used in `helm`,
+  but they might be used by hubs like JFrog Artifactory 
 
 ### Chart Manipulation
 - `POST /api/charts` - upload a new chart version

pkg/chartmuseum/server/multitenant/handlers.go

@@ -146,17 +146,31 @@ func (server *MultiTenantServer) getArtifactHubFileRequestHandler(c *gin.Context
 	c.Data(200, artifactHubFileContentType, artifactHubFile)
 }
 
-func (server *MultiTenantServer) getStorageObjectRequestHandler(c *gin.Context) {
+func (server *MultiTenantServer) getStorageObjectRequestImpl(c *gin.Context) (*StorageObject, *HTTPError) {
 	repo := c.Param("repo")
 	filename := c.Param("filename")
 	log := server.Logger.ContextLoggingFn(c)
-	storageObject, err := server.getStorageObject(log, repo, filename)
+	return server.getStorageObject(log, repo, filename)
+}
+
+func (server *MultiTenantServer) getStorageObjectRequestHandler(c *gin.Context) {
+	storageObject, err := server.getStorageObjectRequestImpl(c)
 	if err != nil {
 		c.JSON(err.Status, gin.H{"error": err.Message})
 		return
 	}
 	c.Data(200, storageObject.ContentType, storageObject.Content)
 }
+
+func (server *MultiTenantServer) headStorageObjectRequestHandler(c *gin.Context) {
+	_, err := server.getStorageObjectRequestImpl(c)
+	if err != nil {
+		c.Status(err.Status)
+		return
+	}
+	c.Status(200)
+}
+
 func (server *MultiTenantServer) getStorageObjectTemplateRequestHandler(c *gin.Context) {
 	repo := c.Param("repo")
 	name := c.Param("name")

pkg/chartmuseum/server/multitenant/routes.go

@@ -39,6 +39,7 @@ func (s *MultiTenantServer) Routes() []*cm_router.Route {
 		{Method: "GET", Path: "/:repo/index.yaml", Handler: s.getIndexFileRequestHandler, Action: cm_auth.PullAction},
 		{Method: "HEAD", Path: "/:repo/index.yaml", Handler: s.headIndexFileRequestHandler, Action: cm_auth.PullAction},
 		{Method: "GET", Path: "/:repo/charts/:filename", Handler: s.getStorageObjectRequestHandler, Action: cm_auth.PullAction},
+		{Method: "HEAD", Path: "/:repo/charts/:filename", Handler: s.headStorageObjectRequestHandler, Action: cm_auth.PullAction},
 	}
 
 	chartManipulationRoutes := []*cm_router.Route{

pkg/chartmuseum/server/multitenant/server_test.go

@@ -1108,6 +1108,13 @@ func (suite *MultiTenantServerTestSuite) testAllRoutes(repo string, depth int) {
 	res = suite.doRequest(stype, "GET", fmt.Sprintf("%s/charts/fakechart-0.1.0.bad", repoPrefix), nil, "")
 	suite.Equal(500, res.Status(), fmt.Sprintf("500 GET %s/charts/fakechart-0.1.0.bad", repoPrefix))
 
+	// HEAD /:repo/charts/:filename
+	res = suite.doRequest(stype, "HEAD", fmt.Sprintf("%s/charts/mychart-0.1.0.tgz", repoPrefix), nil, "")
+	suite.Equal(200, res.Status(), fmt.Sprintf("200 GET %s/charts/mychart-0.1.0.tgz", repoPrefix))
+
+	res = suite.doRequest(stype, "HEAD", fmt.Sprintf("%s/charts/fakechart-0.1.0.bad", repoPrefix), nil, "")
+	suite.Equal(500, res.Status(), fmt.Sprintf("500 GET %s/charts/fakechart-0.1.0.bad", repoPrefix))
+
 	apiPrefix := pathutil.Join("/api", repo)
 
 	// GET /api/:repo/charts