apollo-server-azure-functions: Health checks implementation

[vany0114]

This PR implements health checks for apollo-server-azure-functions package.
Issue: #4925

CC: @glasser

Note: I wasn't able to test this locally since I couldn't build the whole repo, however tests are passing.

[apollo-cla]

@vany0114: Thank you for submitting a pull request! Before we can merge it, you'll need to sign the Apollo Contributor License Agreement here: https://contribute.apollographql.com/

[bennypowers]

I'm implementing in my project with the following patch:

diff

diff --git a/node_modules/apollo-server-azure-functions/.DS_Store b/node_modules/apollo-server-azure-functions/.DS_Store
new file mode 100644
index 0000000..c88a062
Binary files /dev/null and b/node_modules/apollo-server-azure-functions/.DS_Store differ
diff --git a/node_modules/apollo-server-azure-functions/dist/ApolloServer.d.ts b/node_modules/apollo-server-azure-functions/dist/ApolloServer.d.ts
index f8712a4..783bbbf 100644
--- a/node_modules/apollo-server-azure-functions/dist/ApolloServer.d.ts
+++ b/node_modules/apollo-server-azure-functions/dist/ApolloServer.d.ts
@@ -1,5 +1,5 @@
 import { Context, HttpRequest } from '@azure/functions';
-import { ApolloServerBase } from 'apollo-server-core';
+import { ApolloServerBase, Config as ConfigBase } from 'apollo-server-core';
 import { GraphQLOptions } from 'apollo-server-core';
 export interface CreateHandlerOptions {
     cors?: {
@@ -11,8 +11,13 @@ export interface CreateHandlerOptions {
         maxAge?: number;
     };
 }
+export interface Config extends ConfigBase {
+  onHealthCheck?: (context: Context, request: HttpRequest) => Promise<any>;
+}
+
 export declare class ApolloServer extends ApolloServerBase {
     protected serverlessFramework(): boolean;
+    constructor(config: Config);
     createGraphQLServerOptions(request: HttpRequest, context: Context): Promise<GraphQLOptions>;
     createHandler({ cors }?: CreateHandlerOptions): (context: Context, req: HttpRequest) => void;
 }
diff --git a/node_modules/apollo-server-azure-functions/dist/ApolloServer.js b/node_modules/apollo-server-azure-functions/dist/ApolloServer.js
index e95c87a..ec4820c 100644
--- a/node_modules/apollo-server-azure-functions/dist/ApolloServer.js
+++ b/node_modules/apollo-server-azure-functions/dist/ApolloServer.js
@@ -10,6 +10,7 @@ var __awaiter = (this && this.__awaiter) || function (thisArg, _arguments, P, ge
 };
 Object.defineProperty(exports, "__esModule", { value: true });
 exports.ApolloServer = void 0;
+const { URL } = require('url');
 const apollo_server_core_1 = require("apollo-server-core");
 const graphql_playground_html_1 = require("@apollographql/graphql-playground-html");
 const azureFunctionApollo_1 = require("./azureFunctionApollo");
@@ -20,6 +21,10 @@ class ApolloServer extends apollo_server_core_1.ApolloServerBase {
     createGraphQLServerOptions(request, context) {
         return super.graphQLServerOptions({ request, context });
     }
+    constructor(config) {
+        super(config);
+        this.onHealthCheck = config && config.onHealthCheck;
+    }
     createHandler({ cors } = { cors: undefined }) {
         const promiseWillStart = this.willStart();
         const corsHeaders = {};
@@ -79,18 +84,55 @@ class ApolloServer extends apollo_server_core_1.ApolloServerBase {
                 });
                 return;
             }
-            if (this.playgroundOptions && req.method === 'GET') {
-                const acceptHeader = req.headers['Accept'] || req.headers['accept'];
-                if (acceptHeader && acceptHeader.includes('text/html')) {
-                    const path = req.url || '/';
-                    const playgroundRenderPageOptions = Object.assign({ endpoint: path }, this.playgroundOptions);
-                    const body = graphql_playground_html_1.renderPlaygroundPage(playgroundRenderPageOptions);
-                    context.done(null, {
-                        body: body,
-                        status: 200,
-                        headers: Object.assign({ 'Content-Type': 'text/html' }, corsHeaders),
-                    });
-                    return;
+            if (req.method === 'GET') {
+                const url = new URL(req.url);
+                if (url.pathname.endsWith('/.well-known/apollo/server-health')) {
+                    // Response follows https://tools.ietf.org/html/draft-inadarei-api-health-check-01
+                    if (typeof this.onHealthCheck === 'function') {
+                        this.onHealthCheck(context, req)
+                            .then(() => {
+                                context.done(null, {
+                                    body: JSON.stringify({ status: 'pass' }),
+                                    status: 200,
+                                    headers: {
+                                        'Content-Type': 'application/health+json'
+                                    }
+                                });
+                            })
+                            .catch(() => {
+                                context.done(null, {
+                                    body: JSON.stringify({ status: 'fail' }),
+                                    status: 503,
+                                    headers: {
+                                        'Content-Type': 'application/health+json'
+                                    }
+                                });
+                            });
+                        return;
+                    } else {
+                        context.done(null, {
+                            body: JSON.stringify({ status: 'pass' }),
+                            status: 200,
+                            headers: {
+                                'Content-Type': 'application/health+json'
+                            }
+                        });
+                        return;
+                    }
+                }
+                else if (this.playgroundOptions) {
+                    const acceptHeader = req.headers['Accept'] || req.headers['accept'];
+                    if (acceptHeader && acceptHeader.includes('text/html')) {
+                        const path = req.url || '/';
+                        const playgroundRenderPageOptions = Object.assign({ endpoint: path }, this.playgroundOptions);
+                        const body = graphql_playground_html_1.renderPlaygroundPage(playgroundRenderPageOptions);
+                        context.done(null, {
+                            body: body,
+                            status: 200,
+                            headers: Object.assign({ 'Content-Type': 'text/html' }, corsHeaders),
+                        });
+                        return;
+                    }
                 }
             }
             const callbackFilter = (error, output) => {
diff --git a/node_modules/apollo-server-azure-functions/src/ApolloServer.ts b/node_modules/apollo-server-azure-functions/src/ApolloServer.ts
index c0ee393..ceaea20 100644
--- a/node_modules/apollo-server-azure-functions/src/ApolloServer.ts
+++ b/node_modules/apollo-server-azure-functions/src/ApolloServer.ts
@@ -1,6 +1,7 @@
 import { Context, HttpRequest } from '@azure/functions';
 import { HttpResponse } from 'azure-functions-ts-essentials';
-import { ApolloServerBase } from 'apollo-server-core';
+import { ApolloServerBase, Config as ConfigBase } from 'apollo-server-core';
+import { URL } from 'url';
 import { GraphQLOptions } from 'apollo-server-core';
 import {
   renderPlaygroundPage,
@@ -20,11 +21,22 @@ export interface CreateHandlerOptions {
   };
 }
 
+export interface Config extends ConfigBase {
+  onHealthCheck?: (context: Context, request: HttpRequest) => Promise<any>;
+}
+
 export class ApolloServer extends ApolloServerBase {
   protected serverlessFramework(): boolean {
     return true;
   }
 
+  private onHealthCheck?: (context: Context, request: HttpRequest) => Promise<any>;
+
+  constructor(config: Config) {
+    super(config);
+    this.onHealthCheck = config && config.onHealthCheck;
+  }
+
   // This translates the arguments from the middleware into graphQL options It
   // provides typings for the integration specific behavior, ideally this would
   // be propagated with a generic to the super class
@@ -110,25 +122,61 @@ export class ApolloServer extends ApolloServerBase {
         return;
       }
 
-      if (this.playgroundOptions && req.method === 'GET') {
-        const acceptHeader = req.headers['Accept'] || req.headers['accept'];
-        if (acceptHeader && acceptHeader.includes('text/html')) {
-          const path = req.url || '/';
-
-          const playgroundRenderPageOptions: PlaygroundRenderPageOptions = {
-            endpoint: path,
-            ...this.playgroundOptions,
-          };
-          const body = renderPlaygroundPage(playgroundRenderPageOptions);
-          context.done(null, {
-            body: body,
-            status: 200,
-            headers: {
-              'Content-Type': 'text/html',
-              ...corsHeaders,
-            },
-          });
-          return;
+      if (req.method === 'GET') {
+        const url = new URL(req.url);
+        if (url.pathname.endsWith('/.well-known/apollo/server-health')) {
+          // Response follows https://tools.ietf.org/html/draft-inadarei-api-health-check-01
+          if (typeof this.onHealthCheck === 'function') {
+            this.onHealthCheck(context, req)
+              .then(() => {
+                context.done(null, {
+                  body: JSON.stringify({ status: 'pass' }),
+                  status: 200,
+                  headers: {
+                    'Content-Type': 'application/health+json'
+                  }
+                });
+              })
+              .catch(() => {
+                context.done(null, {
+                  body: JSON.stringify({ status: 'fail' }),
+                  status: 503,
+                  headers: {
+                    'Content-Type': 'application/health+json'
+                  }
+                });
+              });
+            return;
+          } else {
+            context.done(null, {
+              body: JSON.stringify({ status: 'pass' }),
+              status: 200,
+              headers: {
+                'Content-Type': 'application/health+json'
+              }
+            });
+            return;
+          }
+        } else if (this.playgroundOptions) {
+          const acceptHeader = req.headers['Accept'] || req.headers['accept'];
+          if (acceptHeader && acceptHeader.includes('text/html')) {
+            const path = req.url || '/';
+
+            const playgroundRenderPageOptions: PlaygroundRenderPageOptions = {
+              endpoint: path,
+              ...this.playgroundOptions,
+            };
+            const body = renderPlaygroundPage(playgroundRenderPageOptions);
+            context.done(null, {
+              body: body,
+              status: 200,
+              headers: {
+                'Content-Type': 'text/html',
+                ...corsHeaders,
+              },
+            });
+            return;
+          }
         }
       }

In order for this to work, I had to use the following function.json

{
  "disabled": false,
  "scriptFile": "../dist/server/graphql/index.js",
  "bindings": [
    {
      "authLevel": "anonymous",
      "type": "httpTrigger",
      "direction": "in",
      "name": "req",
      "route": "{*segments}",
      "methods": [
        "get",
        "post"
      ]
    },
    {
      "type": "http",
      "direction": "out",
      "name": "$return"
    }
  ]
}

[glasser]

@bennypowers Are you suggesting that your change is better than this PR? Should I be reviewing that as a PR instead of this one? Want to file a PR and explain the tradeoffs between yours and this one?

[bennypowers]

I can send over a pr some time in the next two weeks or so.

If OP is interested, they are welcome to implement here.

[glasser]

@bennypowers sure, I'm just curious, does your PR work better than this one for some reason? ie, should I avoid reviewing and merging this one?

[bennypowers]

OP has tests, which my patch lacks

But my patch has the right Content-Type header

In terms of impl details I can't say whether mine is any better than op's. I leave it to reviewers to make that judgement. If parts of my version are adopted in the final merged commit please consider using Co-Authored-By. If this pr is still in flight after Passover I can review OP's tests in light of my patch.

With either version, i'd also love to see a documentation commit with her necessary changes to function.json, as the az func won't work without it

[vany0114]

@beardedtim Oh I see you're using the application/health+json header which makes total sense, I can change it in my PR. On the other hand, I think you're right regarding the function.json file (the "route": "{*segments}" setting) that should be present in the docs.

[vany0114]

Done

[glasser]

Hi, I'm still not sure about what you're saying about the function.json change. Does there need to be an update to docs/source/deployment/azure-functions.md and/or packages/apollo-server-azure-functions/README.md to mention this function.json change?

Also, are you able to resolve conflicts?

[vany0114]

@glasser I updated the docs as well as resolved the conflicts.

[vany0114]

@glasser it seems this broke the docs build, do you know how can I link it or should I just replicate the documentation here?

[glasser]

We don't put anything outside of docs in the docs site, so I'd recommend just linking to the README via a GitHub main branch or npmjs.com link. Replicating sounds good too though.

I'm hoping that as part of the AS3 push we can improve the integration/deployment docs to be more complete and authoritative.

[vany0114]

@glasser done, all the checks are passing now!

[vany0114]

@glasser any plans to merge this soon?

[glasser]

It's on my list of incoming PRs to review, but right now I'm heads down on getting Apollo Server 3 out the door.

[abbeyciolek]

@glasser are there any updates on this PR?

[glasser]

Sorry, there've been a bit of distractions lately (lots of late summer vacations etc) but it's on the queue still and I intend to get a lot of things on that queue done next week!

[abbeyciolek]

@glasser Thank you! Is this change still on track for this week?

[glasser]

This PR appears to still be based on top of Apollo Server 2. I'd be happy to review it (it does make sense to bring this integration to parity with other integrations) once it's rebased on top of current main.

[vany0114]

@glasser I solved the conflicts. I also ran the prettier command however it still shows me an error that does not even make sense, any idea what I'm missing?

[glasser]

override is a new-ish feature of TypeScript so you probably haven't run npm install enough or something?

[vany0114]

override is a new-ish feature of TypeScript so you probably haven't run npm install enough or something?

@glasser would you mind running the prettier --write for me? I'm having issues building locally.

[glasser]

Sure.

[glasser]

The existing code in this PR uses status, not statusCode. Do both actually work? Changing to status for consistency.