Sails: Sails client never connects if client opens when server is down (and then online).

[glemiere]

Node version: 10.9
Sails version _(sails)_:1.2.2
ORM hook version _(sails-hook-orm)_: irrelevant
Sockets hook version _(sails-hook-sockets)_: unknown
Organics hook version _(sails-hook-organics)_: unknown
Grunt hook version _(sails-hook-grunt)_: unused
Uploads hook version _(sails-hook-uploads)_: unknown
DB adapter & version _(e.g. [email protected])_: irrelevant
Skipper adapter & version _(e.g. [email protected])_: unknown

---

The title pretty much says it all.
If I open my web app when the server is down, and then turn the server on, sails client will never succeed to connect.

Meaning that io.socket.on('connect'... will never trigger.

Any idea why? Sounds like a bug to fix.

[sailsbot]

@glemiere Thanks for posting! We'll take a look as soon as possible.

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  ---

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[whichking]

Hey, @glemiere! Are you getting an error in the terminal that you could paste here? It might help me narrow down where things are failing. Thanks!

[glemiere]

Hey @madisonhicks thanks for that fast reply!
I do not get any error per se, however:

• io.socket.disconnect() produces Cannot disconnect- socket is already disconnected
• io.socket.reconnect() produces ERROR Error: Cannot connect- socket is already connecting

So I guess it gets stuck into trying to connect and never fails for or something like that.

My code is within the constructor of a (service) class of an Angular app.
Here it is, maybe it'll help:

    this.isServerDown           = true;
    this.isServerDownChange     = new Subject<boolean>();

    if (this.utils.isBrowser()) {
      this.io                     = sailsIOClient(socketIOClient);
      this.io.sails.url           = this.config.apiUrl;
      this.io.sails.autoConnect   = true;
      this.io.sails.reconnection  = true;
      this.io.sails.initialConnectionHeaders = {
        nosession: true
      };

      this.io.socket.on('disconnect', () => {
        this.isServerDownChange.next(this.isServerDown = true);
      });

      this.io.socket.on('connect', () => {
        this.isServerDownChange.next(this.isServerDown = false);
      });
    }

    this.window.addEventListener('online', () => {
      this.io.socket.reconnect();
    });

    this.window.addEventListener('offline', () => {
      this.io.socket.disconnect();
      this.isServerDownChange.next(this.isServerDown = true);
    });

[whichking]

@glemiere, is it the case that your front end is in a separate Angular application? I haven't been able to reproduce this error on my side, and we don't have a test situation set up that dissociates the front and back end like that. Is it possible for you to create a repository reproducing the error? Thanks!

[glemiere]

@madisonhicks doing this right now, sorry for late reply I've been busier than expected

[glemiere]

@madisonhicks here you go: https://github.com/glemiere/repro-angular-sails-rt-bug

Let me know if you have any question.

The app component : https://github.com/glemiere/repro-angular-sails-rt-bug/blob/master/src/app/app.component.ts

The service communicating with sails:
https://github.com/glemiere/repro-angular-sails-rt-bug/blob/master/src/app/services/api-call.service.ts

The env where you can change the API url:
https://github.com/glemiere/repro-angular-sails-rt-bug/tree/master/src/environments

So you open the app with the SERVER DOWN.
Then you turn the server ON
And it won't turn green with "service online"

Any other case works perfectly.

By default the app connects to localhost:1337.

PS: You need NodeJS v10.9+.
I recommend using NVM for easy version switch.

Oh and thanks for the amazing work done with SailsJS. This framework is totally underrated, I love it! However it'd be nice to implement easier relationship query to avoid doing something like:
https://gist.github.com/glemiere/426e2ada35a775d22a92819122798c5e

Also documentation needs a lot of improvement

[glemiere]

@madisonhicks let me know when you've checked this out

[whichking]

Hey @glemiere! Thanks for the repo and the information. I'll start looking into this as soon as I can, and I should have something for you by the end of my shift tomorrow.

[glemiere]

Thank you very much @madisonhicks!

[whichking]

Hey, @glemiere. It seems like perhaps you want to enable io.sails.reconnection onthe Sails side of things? I created a repo of an empty Sails app, and a pull request setting io.sails.reconnection = true here. Is this helpful?

[glemiere]

Hi @madisonhicks! (Happy July 4th :D)
Unfortunately it's not helping, if you look at the repo I made for you, I already enabled it doing:
this.io.sails.reconnection = true; in https://github.com/glemiere/repro-angular-sails-rt-bug/blob/28d8fd5828ba202d53f246d9099c87cc3526d966/src/app/services/api-call.service.ts#L47

As I said, the problem is that if you open your app while the server is down, sails won't make the attempt to reconnect until the server is back online.
The current behavior will only attempt to reconnect to the server if you opened the app while the server was on, and then only the server went down, not if the server was down since the beginning.

So I guess there is something wrong in the sails client, where if the initial connection fails, the attempt to reconnect never happens.

[whichking]

Hi, @glemiere! Ah, okay. Yeah, the documented behavior of reconnect() is to attempt to reconnect if the server has been disconnected, not when the server starts out down. Is this primarily an issue in development, or do you have a case in production where this is giving you trouble?

[glemiere]

Hi @madisonhicks!
Still in development/staging for now, soon in production.

Here are the things I believe are wrong with the current sails client:

• When it tries to connect for the first time to a down server, it never ends in a case where it definitely failed. It does get stuck in a "connecting" state. Cf second comment above:
  
  
  
  • io.socket.disconnect() produces Cannot disconnect- socket is already disconnected
  
  
  • io.socket.reconnect() produces ERROR Error: Cannot connect- socket is already connecting
  
  

• Being stuck in "connecting" doesn't keep trying to connect to the server.

From that, I think we can work something out. I believe the cleanest solution would be to:

• create a io.sails.persistantConnecting option (boolean, default to false).
  
  
  
  • If set to true it would attempt to connect as long as necessary when connecting for the first time, behaving like io.sails.reconnection.
  
  
  • If set to false it would not insist further when it can't connect with a first attempt. It would instead go back to the "disconnected" state.
  
  

Sounds good? I'm not familiar with that code, but if you send me the repo where the sails client exists I can try to PR something.

[glemiere]

@madisonhicks ?
@johnabrams7 ?

[johnabrams7]

@glemiere Hey, sorry we’ve been a bit busy over the past few days, thanks a ton for all the information and repo so far. We just discussed this as a team and are curious if this is because you’re running into an edge case where: the socket server sails app is offline but then back online before the user has a chance to load a different page or reload the native app?
Also, if it's ok to discuss, what kind of app are you building and what does the traffic look like?

Thanks, we look forward to your response 👍

[glemiere]

Hi @johnabrams7! Thanks for the reply, no big deal we all have a life beside open-source hah! Thanks to you guys for showing interest into this issue.

It's totally okay to discuss in the limit of what's reasonable. I'm building a software meant to be used internally by the company I'm working at right now, so the traffic will be far from crazy, however if it works as expected for us we may open it to other organizations which will increase the traffic. It's a progressive web app and is using two nodes, one for the front (angular) and one for the back (sails).

However it's a tool meant to help us monitor our sprints better, so having it real-time ready is definitely a must. As you can see in the repo I gave you, there is only a single page so it's not coming from the user navigating too soon.

I don't think I'm running into any edge case here because I do put the server offline on purpose to simulate a case where the user opens the app when the sails server is down. When back online the sails client does not automatically connect unless I'm refreshing the page. Ideally I'd like to be able to connect to the server once online without the need to refresh the page, as it's an installable PWA, the goal is to stay as close as possible to a mobile app experience.

PS: Have you been able to run the Angular app?

[glemiere]

@madisonhicks ?
@johnabrams7 ?

[johnabrams7]

Hey @glemiere! - just sent you a text - the team is curious to chat with you further on this one. You can also reach Rachael on her twitter at: https://twitter.com/fancydoilies 👍

[glemiere]

@johnabrams7 Okay just got your text! Thanks for reaching out!

[JaspervRijbroek]

@glemiere Have you found a solution to this issue?

[glemiere]

HI @JaspervRijbroek! Unfortunately not. There is no option to support this in Sails as of today and I don't think there will be any for a while (or ever). So that sucks... I'm not using Sails at the time, but you can check https://nestjs.com/. NestJS is a backend framework definitely inspired by Angular. It looks pretty cool and supports micro-services (no built in support for SNS/SQS though).