Vaadin 8 / Spring Boot / Docker -- resources under .../vaadinServlet/APP/..

Vaadin 6 / 7 / 8
1

I had been hacking together an app with a JavaScript-based front-end, with Spring Security etc. on the backend. I had got so far as to run it load-balanced on a Docker VM cluster.

  • Vaadin 8.5.2
  • Vaadin Push (same)
  • Spring Boot 1.5.16

A week or two ago, I started migrating everything over to Vaadin. By now, everything is playing very nicely on localhost, and I tried pushing it onto Docker.

I’ve been having issues here.

I’m running Vaadin off of an embedded Tomcat server, port 8080.

When running in a Docker VM, almost everything behaves – except for (apparently) anything under .../vaadinServlet/APP/.

  • a static image doesn’t load (GET: http://...:8080/vaadinServlet/APP/connector/0/3/source/logo.png)
  • a POST to my login-form component doesn’t work (POST: http://...:8080/vaadinServlet/APP/connector/0/7/loginForm/loginForm)

Other GETs and POSTs work just fine – e.g.:

  • GET: http://...:8080/VAADIN/themes/portal/styles.css?v=8.5.2
  • GET: http://...:8080/vaadinServlet/PUSH?v-uiId=0&v-pushId=dd09e3c1-a9a3-427a-a500-4479e8296137&...
  • POST: http://...:8080/vaadinServlet/UIDL/?v-uiId=0

Again: when executing simply on localhost, everything works fine.

Has anyone else run into a similar issue? Any bright ideas inspired? Any leads I might follow?

Thanks!

2

Some investigation later –

(random thought: I’m using the [vaadin4spring]
(https://github.com/peholmst/vaadin4spring) project – I wonder how that is affecting anything?)

Attached a debugger to my Docker container so I can watch requests being handled.

Before I get too far: I’m using 2 different UIs in my application:

  1. LoginUI under /login – open to the public, presents login/forgot-password forms
  2. AppUI, under / – authenticated users only

So far, when booting up this app in Docker, I’m trying only to fully render the /login login form.

com.vaadin.server.ConnectorResourceHandler is responsible for fulfilling .../APP/{uiID}/{componentID}/... requests. When, say, my request for .../APP/connector/0/3/source/logo.png comes along, ConnectorResourceHandler.handleRequest(...):

  1. picks it up
  2. determines that the request is handle-able
  3. parses out the UI-ID, component-ID, and “key” (respectively, 0, 3, and source/logo.png
  4. attempts to retrieve the appropriate UI from the current VaadinSession using that UI-ID

That UI-ID is not recognized by the session. OK.

So I put a breakpoint on VaadinSession.addUI(...).

It appears that the VaadinSession picked up by the ConnectorResourceHandler (i.e., the instance passed in as a parameter) is not the same one that receives the addUI(...) call.

Something is up with the way that VaadinSessions are retrieved further up the request-handling stream. Further investigation is indicated.

3

Following up –

I believe I’ve solved my problem – or, at least, isolated it.

In the previous, non-Vaadin version of my app, I’d used Spring Session’s Redis integration to manage session-replication across multiple application-instances (so as to implement load-balancing). Where I went wrong, apparently, is in not giving thought to how Spring Session handles the HttpSession – and how that plays with the VaadinSession.

To avoid showing everyone how little I actually know about how Spring Session works – basically, I cut out Spring Session + Redis from my project, and everything works as expected.

I need to do more research on how Spring Session actually works, and how best to integrate it with Vaadin.

4

Stephen, have you looked more into Spring Session with Vaadin for replication?