apollo-server-lambda v2: expose gateway event and context

Feature Request

Problem

There’re a few usecases I can think of when developing an AWS Lambda with apollo-server where the developer needs access to the original APIGatewayEvent and Context. The current way to develop a lambda in apollo-server v2 is as follows:

exports.graphqlHandler = server.createHandler({
  cors: {
    origin: '*',
    credentials: true
  }
})

create handler takes care of creating the incoming handler that uses the original ApiGatewayEvent and Context. While we can use the context property of ApolloServer for authroization logic to have access to the incoming gateway event and context, there’re some cases where we need the original gateway event before that on the handler level, some of the usecases I can think of is

Usecases

1. Database connection caching To be more specific with Mongoose the recommended way to cache the db connection is by checking it on the handler level as explained here https://mongoosejs.com/docs/lambda.html

2. Warming up the lambda to avoid cold starts and skipping execution if its a warmup check To be more specific using the serverless-plugin-warmup to avoid executing the handler if its a warmup request and do an early return.

3. setting context.callbackWaitsForEmptyEventLoop = false , I believe the created handler by apollo-server already adds this?

4. other initialisation logic like defining a mongoose/database schema, models, etc…

Current Version

apollo-server-lambda v2.9.3

[FlorinDavid]

@khaledosman thank you for context.callbackWaitsForEmptyEventLoop = false hint. My lambda function was hanging in browser GET request when I was training to load the playground page. And I think that was because of the asynchronous MongoDB connection time

I avoided to create the handler on every request and to reconnect to MongoDB so I have done something similar to:

const connect = initConnection() // initConnection() will return a promise

const graphQLHandler = server.createHandler()

exports.handler = (event, context, callback) => {
  context.callbackWaitsForEmptyEventLoop = false

  // initConnection will run only once and after that the promise is fulfilled
  connect.then(() => graphQLHandler(event, context, callback))
}

[khaledosman]

@FlorinDavid Right in mycase I also wanted to share the db connection before hitting graphql’s context to check if the user is authenticated and share him across the resolvers, so I had to do something like this

//handler.js
 connect.then((connection) => graphQLHandler(event, {...context, mongooseConnection: connection}, callback))

then use the db connection in apollo server’s context to have the user or the authentication error accessible from resolvers

//apollo-server.js
 context: async ({ event, context }) => {
    const mongooseConnection = context.mongooseConnection
    try {
      const decodedToken = await validateAuthHeader(event.headers.Authorization)
      // try to retrieve a user with the token
      const User = mongooseConnection.model('User')
      const user = await User.findById(decodedToken._id).lean()
      // add the user to the context
      return { user, mongooseConnection }
    } catch (err) {
      // console.log(err)
      return { mongooseConnection, err }
    }
  },