Remove willStart from apollo-server, already called via `…-expres…

…s`. (#2239)

* Remove `willStart` from `apollo-server`, already called via `...-express`.

When the request pipeline was initially introduced, the integrations
had yet to be updated to call the new life-cycle events.  Now, the
integrations have all caught up, but `apollo-server` is still calling
`willStart`, despite the fact that its dependency which provides the actual
server implementation — `apollo-server-express` – is _also_ calling it,
resulting in double invocation of this event.

I suspect some follow-up work should guard against this possibility, but for
now this should remove the duplication.

* Update CHANGELOG.md for #2239.

Ref: #2239

CHANGELOG.md

@@ -2,7 +2,8 @@
 
 ### vNEXT
 
-- Avoid traversing `graphql-uploads` module tree in run-time environments which aren't Node.js. [PR #2235](https://github.com/apollographql/apollo-server/pull/2235)
+- `apollo-server` (only): Stop double-invocation of `serverWillStart` life-cycle event.  (More specific integrations - e.g. Express, Koa, Hapi, etc. - were unaffected.) [PR #2239](https://github.com/apollographql/apollo-server/pull/2239)
+- Avoid traversing `graphql-upload` module tree in run-time environments which aren't Node.js. [PR #2235](https://github.com/apollographql/apollo-server/pull/2235)
 
 ### v2.3.2
 

packages/apollo-server/src/index.ts

@@ -78,8 +78,6 @@ export class ApolloServer extends ApolloServerBase {
 
   // Listen takes the same arguments as http.Server.listen.
   public async listen(...opts: Array<any>): Promise<ServerInfo> {
-    await this.willStart();
-
     // This class is the easy mode for people who don't create their own express
     // object, so we have to create it.
     const app = express();