Can peerserver work on aws lambda/API gateway ?

[binarythinktank]

As per subject, can it run on lambda or has anyone tried to do this yet?

[xurei]

I'm considering the same as well.

From my understanding, it won't be easy as the connections need to stay open for the heart beats. Am I right ?

[afrokick]

Yes, you are right

[webjay]

Could it be put behind API Gateway WebSocket?

[binarythinktank]

@webjay @xurei yes, i have it working with API gateway sockets and lambda, though its a bit unstable still.

// Load the AWS SDK and modules
const AWS = require('aws-sdk');
const ddb = new AWS.DynamoDB({ apiVersion: '2012-08-10' });
const apigw = new AWS.ApiGatewayManagementApi({ apiVersion: '2018-11-29', endpoint: process.env.socket_url });
const s3 = new AWS.S3({ apiVersion: "2006-03-01", signatureVersion: "v4" });

//all connected to the server users
var users = {};

// send json data to user by connectionId
function sendTo(connectionId, data) {
  apigw.postToConnection({ ConnectionId: connectionId, Data: JSON.stringify(data) }, function (err, data) {
    if (err) {
      console.log("error", err);
    }
  });
}

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

  // missing routekey
  if (typeof event.requestContext === 'undefined' || typeof event.requestContext.routeKey === 'undefined' || event.requestContext.routeKey === '') {
    callback(null, { "statusCode": 401, "body": '{"event":"error","data":"Missing action and routeKey"}' });
    return false;
  }

  // connection ID
  let cid = event.requestContext.connectionId;

  // connect
  if (event.requestContext.routeKey === '$connect') {
    socketConnect();

    // request
  } else if (event.requestContext.routeKey === '$default') {
    socketRequest()

    // disconnect
  } else if (event.requestContext.routeKey === '$disconnect') {
    socketDisconnect()

    // unknown/unsupported request
  } else {
    callback(null, { "result": false, "message": "Unknown request" });
  }

  // CONNECT
  function socketConnect() {

    // create session
    let session = {
      "id": {
        S: cid
      },
      "timestamp": {
        N: new Date().getTime().toString()
      }

      // todo: any other params that need to be tracked
    };

    // store session
    ddb.putItem({
      Item: session,
      TableName: process.env.ddb_sessions
    }, function (err, data) {
      if (err) {
        console.log("Unable to add session to db", err);
        callback(null, { "result": false, "error": "db_error", "message": "Unable to store session" });
        return;
      }

      // all good
      callback(null, { "statusCode": 200, "body": '{"event":"connected"}' });
    });
  }

  // REQUEST
  function socketRequest() {
    // identify user from sessions
    let cid = event.requestContext.connectionId;
    let connection = event.requestContext;

    var data;

    //accepting only JSON messages
    try {
      data = JSON.parse(event.body);
    } catch (e) {
      let errorMessage = "Invalid JSON";
      data = {};
      sendTo(connection, {
        type: "error",
        message: errorMessage
      });
      callback(null, { "result": false, "error": true, "message": errorMessage });
    }

    //switching type of the user message
    switch (data.type) {
      //when a user tries to login

      case "login":

        //if anyone is logged in with this username then refuse
        if (users[data.name]) {
          sendTo(connection, {
            type: "login",
            success: false
          });
        } else {
          //save user connection on the server
          users[data.name] = connection;
          connection.name = data.name;

          sendTo(connection.connectionId, {
            type: "login",
            success: true,
            connectionId: connection.connectionId
          });
        }

        break;

      case "offer":
        //if UserB exists then send him offer details
        var conn = users[data.name];

        if (conn != null) {
          //setting that UserA connected with UserB
          connection.otherName = data.name;

          sendTo(conn.connectionId, {
            type: "offer",
            offer: data.offer,
            name: data.myName,
            connectionId: conn.connectionId,
            myConnId: connection.connectionId
          });
        }

        break;

      case "answer":
        //for ex. UserB answers UserA
        sendTo(data.connectedUserId, {
          type: "answer",
          answer: data.answer,
          connectionId: data.connectedUserId,
          myConnId: connection.connectionId
        });

        break;

      case "candidate":
        let connCand = users[data.name];

        if (data.hasOwnProperty("connectedUserId")) {
          sendTo(data.connectedUserId, {
            type: "candidate",
            candidate: data.candidate,
            name: data.myName,
            myConnId: connection.connectionId
          });
        }

        if (connCand != null) {
          sendTo(connCand.connectionId, {
            type: "candidate",
            name: data.myName,
            candidate: data.candidate,
            connectionId: connCand.connectionId,
            myConnId: connection.connectionId
          });
        }

        break;

      case "leave":
        sendTo(data.connectedUserId, {
          type: "leave"
        });

        break;

      case "createSignedUrl":
        let fields = {
          key: data.filename,
          "x-amz-meta-eventid": data.eventid,
          "x-amz-meta-role": data.role,
          "x-amz-meta-mimetype": data.mimetype,
          "x-amz-meta-length": data.video_length
        };

        s3.createPresignedPost({ Bucket: process.env.s3_archive, Fields: fields, Expires: 7200 }, function (err, res) {
          let bodyData = {};

          if (err) {
            bodyData = { "event": "error", "data": "Unable to get signed URL" }
            callback(null, { "statusCode": 401, "body": JSON.stringify(bodyData) });
            return false;
          }

          bodyData = {
            "event": "success",
            "data": {
              "url": res.url,
              "expires": new Date().getTime() + 7200000,
              "fields": res.fields
            }
          }

          // response
          callback(null, { "statusCode": 200, "body": JSON.stringify(bodyData["data"]) });
          sendTo(cid, {
            type: "signedUrl",
            data: bodyData
          });
        });

        break;

      default:
        sendTo(connection, {
          type: "error",
          message: "Command not found: " + data.type
        });

        break;
    }

    // response
    callback(null, { "statusCode": 200, "body": JSON.stringify({}) });

  }

  // DISCONNECT
  function socketDisconnect() {
    // identify user from sessions
    let cid = event.requestContext.connectionId;

    // todo: any actions needed for disconnect?

    // done
    callback(null, { "statusCode": 200, "body": '{"event":"disconnected"}' });
  }

};

[xurei]

@binarythinktank Thank you for the code ! I didn't read it thoroughly, but can you explain how you deal with the heart beats ? Are you keeping the app always on ? Also, is there any data persistence involved ?

[binarythinktank]

you could handle heartbeats if you want, api gateway is always available and it will call lambda when needed, too many lambda requests might get expensive though. there's some ddb in there to track sessions, you could expand on that to track other stuff if you need it.