Use discovery api to build URLs in techdocs

Use the discovery api to build catalog API URLs and URLs to locally published
metadata.

plugins/techdocs-backend/src/service/router.ts

@@ -62,7 +62,13 @@ export async function createRouter({
   const router = Router();
 
   router.get('/metadata/mkdocs/*', async (req, res) => {
-    const storageUrl = config.getString('techdocs.storageUrl');
+    let storageUrl = config.getString('techdocs.storageUrl');
+    if (publisher instanceof LocalPublish) {
+      storageUrl = new URL(
+        new URL(storageUrl).pathname,
+        await discovery.getBaseUrl('techdocs'),
+      ).toString();
+    }
     const { '0': path } = req.params;
 
     const metadataURL = `${storageUrl}/${path}/techdocs_metadata.json`;
@@ -77,13 +83,14 @@ export async function createRouter({
   });
 
   router.get('/metadata/entity/:namespace/:kind/:name', async (req, res) => {
-    const baseUrl = config.getString('backend.baseUrl');
+    const catalogUrl = await discovery.getBaseUrl('catalog');
+
     const { kind, namespace, name } = req.params;
 
     try {
       const entity = (await (
         await fetch(
-          `${baseUrl}/api/catalog/entities/by-name/${kind}/${namespace}/${name}`,
+          `${catalogUrl}/entities/by-name/${kind}/${namespace}/${name}`,
         )
       ).json()) as Entity;