Ensure subsequent page reads are run through the proxy

Signed-off-by: Robert Bunning <rbunning@webstaurantstore.com>

plugins/newrelic/src/api/index.test.ts

@@ -126,7 +126,7 @@ describe('NewRelicClient', () => {
           headers: new Map<string, string | null>([
             [
               'link',
-              '<https://next.page/page2>; rel="next", <https://badsite.dontgohere>; rel="next"',
+              '<https://next.page/page2?page=2>; rel="next", <https://badsite.dontgohere>; rel="next"',
             ],
             ['otherheader', 'otherValue'],
           ]),
@@ -135,7 +135,7 @@ describe('NewRelicClient', () => {
           ok: true,
           json: async () => ({ applications: [] }),
           headers: new Map<string, string | null>([
-            ['Link', '<https://next.page/page3>; rel="next",'],
+            ['Link', '<https://next.page/page3?page=3>; rel="next",'],
           ]),
         })
         .mockResolvedValueOnce({
@@ -170,10 +170,10 @@ describe('NewRelicClient', () => {
       'https://test.test/newrelic/apm/api/applications.json',
     );
     expect(mockedFetchApi.fetch).toHaveBeenCalledWith(
-      'https://next.page/page2',
+      'https://test.test/newrelic/apm/api/applications.json?page=2',
     );
     expect(mockedFetchApi.fetch).toHaveBeenCalledWith(
-      'https://next.page/page3',
+      'https://test.test/newrelic/apm/api/applications.json?page=3',
     );
     expect(actual).toStrictEqual(expected);
   });
@@ -220,6 +220,7 @@ describe('NewRelicClient', () => {
     ['<>; rel:"value"'],
     ['<https://next.page>; rel: "next"'],
     ['ABCDE'],
+    ['<https://next.page/page3?page=>; rel="next",'],
   ])(
     'It does not attempt pagination when the link header value is invalid (%p)',
     async linkHeaderValue => {
@@ -309,4 +310,29 @@ describe('NewRelicClient', () => {
 
     expect(actual).toStrictEqual({ applications: [] });
   });
+
+  it('Generates the base url only once', async () => {
+    const mockedDiscoveryApi: DiscoveryApi = {
+      getBaseUrl: jest.fn().mockResolvedValueOnce('https://test.test'),
+    };
+
+    const mockedFetchApi: FetchApi = {
+      fetch: jest.fn().mockResolvedValue({
+        ok: true,
+        json: async () => ({ applications: [] }),
+      }),
+    };
+
+    const client = new NewRelicClient({
+      discoveryApi: mockedDiscoveryApi,
+      fetchApi: mockedFetchApi,
+    });
+
+    await client.getApplications();
+    await client.getApplications();
+    await client.getApplications();
+    await client.getApplications();
+
+    expect(mockedDiscoveryApi.getBaseUrl).toHaveBeenCalledTimes(1);
+  });
 });

plugins/newrelic/src/api/index.ts

@@ -91,16 +91,22 @@ export class NewRelicClient implements NewRelicApi {
   private readonly discoveryApi: DiscoveryApi;
   private readonly fetchApi: FetchApi;
   private readonly proxyPathBase: string;
+  private baseUrl: string;
 
   constructor(options: Options) {
     this.discoveryApi = options.discoveryApi;
     this.fetchApi = options.fetchApi;
     this.proxyPathBase = options.proxyPathBase ?? DEFAULT_PROXY_PATH_BASE;
+    this.baseUrl = '';
   }
 
   async getApplications(): Promise<NewRelicApplications> {
-    const proxyUrl = await this.discoveryApi.getBaseUrl('proxy');
-    let targetUrl = `${proxyUrl}${this.proxyPathBase}/apm/api/applications.json`;
+    if (!this.baseUrl) {
+      const proxyUrl = await this.discoveryApi.getBaseUrl('proxy');
+      this.baseUrl = `${proxyUrl}${this.proxyPathBase}/apm/api/applications.json`;
+    }
+
+    let targetUrl = this.baseUrl;
     let hasNextPage = true;
 
     try {
@@ -111,7 +117,7 @@ export class NewRelicClient implements NewRelicApi {
           await this.fetchNewRelic(targetUrl);
 
         hasNextPage = hasMoreApplications;
-        targetUrl = pagination!.nextPageLink;
+        targetUrl = hasNextPage ? pagination!.nextPageLink : '';
         applications = applications.concat(applicationsFromReadPage);
       } while (hasNextPage);
 
@@ -155,12 +161,12 @@ export class NewRelicClient implements NewRelicApi {
     }
 
     const nextRelevantLink = linkHeader.replaceAll(' ', '').split(',')[0];
-
-    // Link should be of the format <nextPageLink>;rel="relation"
-    const linkParts = nextRelevantLink.match(/^<(.+)>;rel="(.+)"$/);
-    const nextPageLink = linkParts?.[1];
+    const linkParts = nextRelevantLink.match(/^<.+(\?page=.+)>;rel="(.+)"$/);
+    const nextPageNumber = linkParts?.[1];
     const relation = linkParts?.[2];
-    const isValidLink = !!(!!linkParts && nextPageLink && relation);
+
+    const nextPageLink = `${this.baseUrl}${nextPageNumber}`;
+    const isValidLink = !!(!!linkParts && nextPageNumber && relation);
 
     if (!nextRelevantLink || !isValidLink) {
       return undefined;