refactor: Use {{pluginId}} pattern and update docs

Signed-off-by: Jack Palmer <jackpalmer@spotify.com>

packages/backend-common/config.d.ts

@@ -217,7 +217,7 @@ export interface Config {
        * The target baseUrl to use for the plugin
        *
        * Can be either a string or an object with internal and external keys.
-       * Targets with `{pluginId}` in the url will be replaced with the pluginId.
+       * Targets with `{{pluginId}}` or `{{ pluginId }} in the url will be replaced with the pluginId.
        */
       target: string | { internal: string; external: string };
       /** Array of plugins which use the target baseUrl. */

packages/backend-common/src/discovery/HostDiscovery.test.ts

@@ -163,7 +163,7 @@ describe('HostDiscovery', () => {
     );
   });
 
-  it('replaces {pluginId} in the target', async () => {
+  it('replaces {{pluginId}} or {{ pluginId }} in the target', async () => {
     const discovery = HostDiscovery.fromConfig(
       new ConfigReader({
         backend: {
@@ -173,13 +173,13 @@ describe('HostDiscovery', () => {
         discovery: {
           endpoints: [
             {
-              target: 'http://common-backend:8080/api/{pluginId}',
+              target: 'http://common-backend:8080/api/{{pluginId}}',
               plugins: ['catalog', 'docs'],
             },
             {
               target: {
-                internal: 'http://scaffolder-internal:8080/api/{pluginId}',
-                external: 'http://scaffolder-external:8080/api/{pluginId}',
+                internal: 'http://scaffolder-internal:8080/api/{{ pluginId }}',
+                external: 'http://scaffolder-external:8080/api/{{ pluginId }}',
               },
               plugins: ['scaffolder'],
             },

packages/backend-common/src/discovery/HostDiscovery.ts

@@ -37,7 +37,20 @@ export class HostDiscovery implements PluginEndpointDiscovery {
    * discovering the external URL, and the `.listen` and `.https` config
    * for the internal one.
    *
-   * Can be overridden by in config by providing a `discovery` section with a `<pluginId>` key.
+   * Can be overridden by in config by providing a target and corresponding plugin in `discovery.endpoint`.
+   * eg.
+   * ```yaml
+   * discovery:
+   *  endpoints:
+   *    - target: https://internal.example.com/internal-catalog
+   *      plugins: [catalog]
+   *    - target: https://internal.example.com/secure/api/{{pluginId}}
+   *      plugins: [auth, permissions]
+   *    - target:
+   *        internal: https://internal.example.com/search
+   *        external: https://example.com/search
+   *      plugins: [search]
+   * ```
    *
    * The basePath defaults to `/api`, meaning the default full internal
    * path for the `catalog` plugin will be `http://localhost:7007/api/catalog`.
@@ -92,10 +105,10 @@ export class HostDiscovery implements PluginEndpointDiscovery {
     }
 
     if (typeof target === 'string') {
-      return target.replace('{pluginId}', pluginId);
+      return target.replace(/\{\{\s*pluginId\s*\}\}/, pluginId);
     }
 
-    return target[type].replace('{pluginId}', pluginId);
+    return target[type].replace(/\{\{\s*pluginId\s*\}\}/, pluginId);
   }
 
   async getBaseUrl(pluginId: string): Promise<string> {