From a20bc00b41fd999f40e2c30bc11533ff51c49164 Mon Sep 17 00:00:00 2001
From: Patrik Oldsberg <poldsberg@gmail.com>
Date: Tue, 8 Sep 2020 19:42:36 +0200
Subject: [PATCH] plugins/circleci: refactor to use DiscoverApi

---
 docs/api/utility-apis.md          |  4 ++--
 plugins/circleci/dev/index.tsx    | 10 +--------
 plugins/circleci/src/api/index.ts | 34 +++++++++++++++++++++++--------
 plugins/circleci/src/plugin.ts    | 13 ++++++------
 4 files changed, 36 insertions(+), 25 deletions(-)

diff --git a/docs/api/utility-apis.md b/docs/api/utility-apis.md
index d192cbd6ee..599bbbb66c 100644
--- a/docs/api/utility-apis.md
+++ b/docs/api/utility-apis.md
@@ -97,7 +97,7 @@ app, and the app itself.
 
 ### Core APIs
 
-Starting with the Backstage core library, it provides implementation for all of
+Starting with the Backstage core library, it provides implementations for all of
 the core APIs. The core APIs are the ones exported by `@backstage/core`, such as
 the `errorApiRef` and `configApiRef`. You can find a full list of them
 [here](../reference/utility-apis/README.md).
@@ -113,7 +113,7 @@ While doing so they should usually also provide default implementations of their
 own APIs, for example, the `catalog` plugin exports `catalogApiRef`, and also
 supplies a default `ApiFactory` of that API using the `CatalogClient`. There is
 one restriction to plugin-provided API Factories: plugins may not supply
-factories for core APIs, trying to do so will cause the app to crash.
+factories for core APIs, trying to do so will cause the app to refuse to start.
 
 Plugins supply their APIs through the `apis` option of `createPlugin`, for
 example:
diff --git a/plugins/circleci/dev/index.tsx b/plugins/circleci/dev/index.tsx
index 4bf67d5cb2..812a5585d4 100644
--- a/plugins/circleci/dev/index.tsx
+++ b/plugins/circleci/dev/index.tsx
@@ -16,13 +16,5 @@
 
 import { createDevApp } from '@backstage/dev-utils';
 import { plugin } from '../src/plugin';
-import { circleCIApiRef, CircleCIApi } from '../src/api';
 
-createDevApp()
-  .registerPlugin(plugin)
-  .registerApi({
-    api: circleCIApiRef,
-    deps: {},
-    factory: () => new CircleCIApi(),
-  })
-  .render();
+createDevApp().registerPlugin(plugin).render();
diff --git a/plugins/circleci/src/api/index.ts b/plugins/circleci/src/api/index.ts
index da4c811812..c71be6b781 100644
--- a/plugins/circleci/src/api/index.ts
+++ b/plugins/circleci/src/api/index.ts
@@ -26,7 +26,7 @@ import {
   BuildSummary,
   GitType,
 } from 'circleci-api';
-import { createApiRef } from '@backstage/core';
+import { createApiRef, DiscoveryApi } from '@backstage/core';
 
 export { GitType };
 export type { BuildWithSteps, BuildStepAction, BuildSummary };
@@ -36,15 +36,28 @@ export const circleCIApiRef = createApiRef<CircleCIApi>({
   description: 'Used by the CircleCI plugin to make requests',
 });
 
+const DEFAULT_PROXY_PATH = '/circleci/api';
+
+type Options = {
+  discoveryApi: DiscoveryApi;
+  /**
+   * Path to use for requests via the proxy, defaults to /circleci/api
+   */
+  proxyPath?: string;
+};
+
 export class CircleCIApi {
-  apiUrl: string;
-  constructor(apiUrl: string = '/circleci/api') {
-    this.apiUrl = apiUrl;
+  private readonly discoveryApi: DiscoveryApi;
+  private readonly proxyPath: string;
+
+  constructor(options: Options) {
+    this.discoveryApi = options.discoveryApi;
+    this.proxyPath = options.proxyPath ?? DEFAULT_PROXY_PATH;
   }
 
   async retry(buildNumber: number, options: Partial<CircleCIOptions>) {
     return postBuildActions('', buildNumber, BuildAction.RETRY, {
-      circleHost: this.apiUrl,
+      circleHost: await this.getApiUrl(),
       ...options.vcs,
     });
   }
@@ -59,19 +72,24 @@ export class CircleCIApi {
         offset,
       },
       vcs: {},
-      circleHost: this.apiUrl,
+      circleHost: await this.getApiUrl(),
       ...options,
     });
   }
 
   async getUser(options: Partial<CircleCIOptions>) {
-    return getMe('', { circleHost: this.apiUrl, ...options });
+    return getMe('', { circleHost: await this.getApiUrl(), ...options });
   }
 
   async getBuild(buildNumber: number, options: Partial<CircleCIOptions>) {
     return getFullBuild('', buildNumber, {
-      circleHost: this.apiUrl,
+      circleHost: await this.getApiUrl(),
       ...options.vcs,
     });
   }
+
+  private async getApiUrl() {
+    const proxyUrl = await this.discoveryApi.getBaseUrl('proxy');
+    return proxyUrl + this.proxyPath;
+  }
 }
diff --git a/plugins/circleci/src/plugin.ts b/plugins/circleci/src/plugin.ts
index f966caa383..c5bb122ed3 100644
--- a/plugins/circleci/src/plugin.ts
+++ b/plugins/circleci/src/plugin.ts
@@ -14,7 +14,11 @@
  * limitations under the License.
  */
 
-import { createPlugin, createApiFactory, configApiRef } from '@backstage/core';
+import {
+  createPlugin,
+  createApiFactory,
+  discoveryApiRef,
+} from '@backstage/core';
 import { circleCIApiRef, CircleCIApi } from './api';
 
 export const plugin = createPlugin({
@@ -22,11 +26,8 @@ export const plugin = createPlugin({
   apis: [
     createApiFactory({
       api: circleCIApiRef,
-      deps: { configApi: configApiRef },
-      factory: ({ configApi }) =>
-        new CircleCIApi(
-          `${configApi.getString('backend.baseUrl')}/proxy/circleci/api`,
-        ),
+      deps: { discoveryApi: discoveryApiRef },
+      factory: ({ discoveryApi }) => new CircleCIApi({ discoveryApi }),
     }),
   ],
 });