Add demand control for uplink

gateway-js/CHANGELOG.md

@@ -6,7 +6,7 @@ This CHANGELOG pertains only to Apollo Federation packages in the 2.x range. The
 
 > The changes noted within this `vNEXT` section have not been released yet.  New PRs and commits which introduce changes should include an entry in this `vNEXT` section as part of their development.  When a release is being prepared, a new header will be (manually) created below and the appropriate changes within that release will be moved into the new section.
 
-- _Nothing yet.  Stay tuned!_
+- Respect the `minDelaySeconds` returning from Uplink when polling and retrying to fetch the supergraph schema from Uplink [PR #1564](https://github.com/apollographql/federation/pull/1564)
 
 ## v2.0.0-preview.2
 

gateway-js/src/config.ts

@@ -81,6 +81,7 @@ export interface ServiceDefinitionUpdate {
 export interface SupergraphSdlUpdate {
   id: string;
   supergraphSdl: string;
+  minDelaySeconds?: number;
 }
 
 export function isSupergraphSdlUpdate(

gateway-js/src/supergraphManagers/UplinkFetcher/__tests__/loadSupergraphSdlFromStorage.test.ts

@@ -65,6 +65,7 @@ describe('loadSupergraphSdlFromStorage', () => {
       compositionId: "originalId-1234",
       maxRetries: 1,
       roundRobinSeed: 0,
+      earliestFetchTime: null,
     });
 
     expect(result).toMatchObject({
@@ -88,6 +89,7 @@ describe('loadSupergraphSdlFromStorage', () => {
         compositionId: "originalId-1234",
         maxRetries: 1,
         roundRobinSeed: 0,
+        earliestFetchTime: null,
       }),
     ).rejects.toThrowError(
       new UplinkFetcherError(
@@ -388,10 +390,49 @@ describe("loadSupergraphSdlFromUplinks", () => {
       compositionId: "id-1234",
       maxRetries: 5,
       roundRobinSeed: 0,
+      earliestFetchTime: null,
     });
 
     expect(result).toBeNull();
     expect(fetcher).toHaveBeenCalledTimes(1);
   });
+
+  it("Waits the correct time before retrying", async () => {
+    const timeoutSpy = jest.spyOn(global, 'setTimeout');
+
+    mockSupergraphSdlRequest('originalId-1234', mockCloudConfigUrl1).reply(500);
+    mockSupergraphSdlRequestIfAfter('originalId-1234', mockCloudConfigUrl2).reply(
+      200,
+      JSON.stringify({
+        data: {
+          routerConfig: {
+            __typename: 'RouterConfigResult',
+            id: 'originalId-1234',
+            supergraphSdl: getTestingSupergraphSdl()
+          },
+        },
+      }),
+    );
+    const fetcher = getDefaultFetcher();
+
+    await loadSupergraphSdlFromUplinks({
+      graphRef,
+      apiKey,
+      endpoints: [mockCloudConfigUrl1, mockCloudConfigUrl2],
+      errorReportingEndpoint: undefined,
+      fetcher: fetcher,
+      compositionId: "originalId-1234",
+      maxRetries: 1,
+      roundRobinSeed: 0,
+      earliestFetchTime: new Date(Date.now() + 1000),
+    });
+
+    // test if setTimeout was called with a value in range to deal with time jitter
+    const setTimeoutCall = timeoutSpy.mock.calls[1][1];
+    expect(setTimeoutCall).toBeLessThanOrEqual(1000);
+    expect(setTimeoutCall).toBeGreaterThanOrEqual(900);
+
+    timeoutSpy.mockRestore();
+  });
 });
 

gateway-js/src/supergraphManagers/UplinkFetcher/index.ts

@@ -31,6 +31,8 @@ export class UplinkFetcher implements SupergraphManager {
     process.env.APOLLO_OUT_OF_BAND_REPORTER_ENDPOINT ?? undefined;
   private compositionId?: string;
   private fetchCount: number = 0;
+  private minDelayMs: number | null = null;
+  private earliestFetchTime: Date | null = null;
 
   constructor(options: UplinkFetcherOptions) {
     this.config = options;
@@ -46,7 +48,12 @@ export class UplinkFetcher implements SupergraphManager {
 
     let initialSupergraphSdl: string | null = null;
     try {
-      initialSupergraphSdl = await this.updateSupergraphSdl();
+      const result = await this.updateSupergraphSdl();
+      initialSupergraphSdl = result?.supergraphSdl || null;
+      if (result?.minDelaySeconds) {
+        this.minDelayMs = 1000 * result?.minDelaySeconds;
+        this.earliestFetchTime = new Date(Date.now() + this.minDelayMs);
+      }
     } catch (e) {
       this.logUpdateFailure(e);
       throw e;
@@ -83,6 +90,7 @@ export class UplinkFetcher implements SupergraphManager {
       compositionId: this.compositionId ?? null,
       maxRetries: this.config.maxRetries,
       roundRobinSeed: this.fetchCount++,
+      earliestFetchTime: this.earliestFetchTime,
     });
 
     if (!result) {
@@ -91,7 +99,8 @@ export class UplinkFetcher implements SupergraphManager {
       this.compositionId = result.id;
       // the healthCheck fn is only assigned if it's enabled in the config
       await this.healthCheck?.(result.supergraphSdl);
-      return result.supergraphSdl;
+      const { supergraphSdl, minDelaySeconds } = result;
+      return { supergraphSdl, minDelaySeconds };
     }
   }
 
@@ -107,7 +116,12 @@ export class UplinkFetcher implements SupergraphManager {
 
         this.state.pollingPromise = pollingPromise;
         try {
-          const maybeNewSupergraphSdl = await this.updateSupergraphSdl();
+          const result = await this.updateSupergraphSdl();
+          const maybeNewSupergraphSdl = result?.supergraphSdl || null;
+          if (result?.minDelaySeconds) {
+            this.minDelayMs = 1000 * result?.minDelaySeconds;
+            this.earliestFetchTime = new Date(Date.now() + this.minDelayMs);
+          }
           if (maybeNewSupergraphSdl) {
             this.update?.(maybeNewSupergraphSdl);
           }
@@ -118,7 +132,7 @@ export class UplinkFetcher implements SupergraphManager {
       }
 
       this.poll();
-    }, this.config.pollIntervalInMs);
+    }, this.minDelayMs ? Math.max(this.minDelayMs, this.config.pollIntervalInMs) : this.config.pollIntervalInMs);
   }
 
   private logUpdateFailure(e: any) {

gateway-js/src/supergraphManagers/UplinkFetcher/loadSupergraphSdlFromStorage.ts

@@ -13,6 +13,7 @@ export const SUPERGRAPH_SDL_QUERY = /* GraphQL */`#graphql
       ... on RouterConfigResult {
         id
         supergraphSdl: supergraphSDL
+        minDelaySeconds
       }
       ... on FetchError {
         code
@@ -56,6 +57,7 @@ export async function loadSupergraphSdlFromUplinks({
   compositionId,
   maxRetries,
   roundRobinSeed,
+  earliestFetchTime,
 }: {
   graphRef: string;
   apiKey: string;
@@ -65,6 +67,7 @@ export async function loadSupergraphSdlFromUplinks({
   compositionId: string | null;
   maxRetries: number,
   roundRobinSeed: number,
+  earliestFetchTime: Date | null
 }) : Promise<SupergraphSdlUpdate | null> {
   // This Promise resolves with either an updated supergraph or null if no change.
   // This Promise can reject in the case that none of the retries are successful,
@@ -81,6 +84,10 @@ export async function loadSupergraphSdlFromUplinks({
       }),
     {
       retries: maxRetries,
+      onRetry: async () => {
+        const delayMS = earliestFetchTime ? earliestFetchTime.getTime() - Date.now(): 0;
+        if (delayMS > 0) await new Promise(resolve => setTimeout(resolve, delayMS));
+      }
     },
   );
 
@@ -176,9 +183,10 @@ export async function loadSupergraphSdlFromStorage({
     const {
       id,
       supergraphSdl,
+      minDelaySeconds,
       // messages,
     } = routerConfig;
-    return { id, supergraphSdl: supergraphSdl! };
+    return { id, supergraphSdl: supergraphSdl!, minDelaySeconds };
   } else if (routerConfig.__typename === 'FetchError') {
     // FetchError case
     const { code, message } = routerConfig;