changelog: add proxy in the operator http server

this will allow to display the changelog using the Rancher UI URL:

https://<RancherURL>/elemental/changelog/<ManagedOSVersion.Name>

which is set in the ManagedOSChangelog.status.changelogURL

Signed-off-by: Francesco Giudici <francesco.giudici@suse.com>

pkg/server/api_changelog.go

@@ -0,0 +1,109 @@
+/*
+Copyright © 2022 - 2024 SUSE LLC
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+package server
+
+import (
+	"fmt"
+	"net/http"
+	"net/http/httputil"
+	"net/url"
+	"path"
+	"strings"
+
+	corev1 "k8s.io/api/core/v1"
+
+	elementalv1 "github.com/rancher/elemental-operator/api/v1beta1"
+	"k8s.io/apimachinery/pkg/types"
+)
+
+func (i *InventoryServer) apiChangelog(resp http.ResponseWriter, req *http.Request, splittedPath []string) error {
+	var err error
+	var changelog *elementalv1.ManagedOSChangelog
+
+	// expected splittedPath = {"changelog", {ManagedOSVersion.Name}}
+	if len(splittedPath) < 2 {
+		err = fmt.Errorf("unexpected path: %v", splittedPath)
+		http.Error(resp, err.Error(), http.StatusNotFound)
+		return err
+	}
+	osVersion := splittedPath[1]
+	filename := ""
+	if len(splittedPath) == 3 {
+		filename = splittedPath[2]
+	}
+
+	if changelog, err = i.getManagedOSChangelog(osVersion); err != nil {
+		http.Error(resp, err.Error(), http.StatusNotFound)
+		return err
+	}
+
+	svc := &corev1.Service{}
+	if err = i.Get(i, types.NamespacedName{Namespace: changelog.Namespace, Name: changelog.Name}, svc); err != nil {
+		errMsg := fmt.Errorf("failed to get service for changelog %s/%s: %w", changelog.Namespace, changelog.Name, err)
+		http.Error(resp, errMsg.Error(), http.StatusInternalServerError)
+		return errMsg
+	}
+
+	rawURL := fmt.Sprintf("http://%s/%s", svc.Spec.ClusterIP, filename)
+	seedImgURL, err := url.Parse(rawURL)
+	if err != nil {
+		errMsg := fmt.Errorf("failed to parse url '%s'", rawURL)
+		http.Error(resp, errMsg.Error(), http.StatusInternalServerError)
+		return errMsg
+	}
+	director := func(r *http.Request) {
+		r.URL = seedImgURL
+	}
+
+	reverseProxy := &httputil.ReverseProxy{
+		Director: director,
+	}
+	reverseProxy.ServeHTTP(resp, req)
+
+	return nil
+}
+
+func (i *InventoryServer) getManagedOSChangelog(osVersion string) (*elementalv1.ManagedOSChangelog, error) {
+	escapedToken := strings.Replace(osVersion, "\n", "", -1)
+	escapedToken = strings.Replace(escapedToken, "\r", "", -1)
+
+	changelogList := &elementalv1.ManagedOSChangelogList{}
+	if err := i.List(i, changelogList); err != nil {
+		return nil, fmt.Errorf("failed to list managedoschangelogs")
+	}
+
+	var changelog *elementalv1.ManagedOSChangelog
+
+	for _, c := range changelogList.Items {
+		if path.Base(c.Spec.ManagedOSVersion) == escapedToken {
+			changelog = (&c).DeepCopy()
+			break
+		}
+	}
+
+	if changelog == nil {
+		return nil, fmt.Errorf("failed to find changelog with ManagedOSVersion %s", escapedToken)
+	}
+
+	for _, condition := range changelog.Status.Conditions {
+		if condition.Status != "True" {
+			return nil, fmt.Errorf("changelog %s/%s is not ready", changelog.Namespace, changelog.Name)
+		}
+	}
+
+	return changelog, nil
+}

pkg/server/server.go

@@ -87,7 +87,11 @@ func (i *InventoryServer) ServeHTTP(resp http.ResponseWriter, req *http.Request)
 			log.Errorf("seedimage download: %s", err.Error())
 			return
 		}
-
+	case "changelog":
+		if err := i.apiChangelog(resp, req, splittedPath); err != nil {
+			log.Errorf("changelog download: %s", err.Error())
+			return
+		}
 	default:
 		log.Errorf("Unknown API: %s", api)
 		http.Error(resp, fmt.Sprintf("unknwon api: %s", api), http.StatusBadRequest)