Websocket example/support?

[misha]

I'm exploring the Lapis/OpenResty/Nginx stack for personal project. I noticed that OpenResty has support for websockets; is it possible to reach through Lapis, or integrate websockets somehow? I looked around GitHub and the Lapis reference manual but I didn't find anything.

Examples/documentation/thoughts are welcome.

[lordnynex]

@msoliter Lapis does not currently support websockets. I've been thinking about this lately for some lapis projects of mine and I think it would be awesome to hear @leafo's thoughts on including support for it. It's a non-trivial change though because of the way openresty/lua-resty-websocket works. As a hack you can implement your websocket loop in another location {} directive and use ngx.location.capture() to pass messages back and forth to lapis. I would not recommend this hack for a heavy traffic scenario.

@leafo if websockets are on the road map (it would be exciting if it was) and you're overhauling the dispatcher I think it would be awesome to have an alternative to serve() which works in the ACCESS phase to bypass the output buffer. Aside from being able to check session state outside a before_filter, I would be able to do basic request validation before passing the request onto the content phase. I've seen a fair bit of requests for lapis in the access phase and I'm curious what your thoughts are on this.

[bdjnk]

The integration of websockets into Lapis is a feature that interests me as well. It would be good to get input from @leafo on the possibility.

[revskill10]

There is a websocket module there. Is it production ready ?

[nonchip]

@checkraiser where is there?

[jots]

+1 for websockets in lapis.

[aiibe]

+1 websockets supported in Lapis

[chelog]

Would be a great thing to see websockets in Lapis as we're using it in our community for almost every web thingie

+1 here

[nonchip]

interesting to see how there isn't even a simple statement on this feature request for 3 years while implementing websocket support in other non-monolithic-as-hell frameworks that don't even support it yet takes about half an hour of trial and error... seems like @leafo doesn't even care enough anymore to talk to us if it can't sell us an itch.io feature...

[ghost]

Not having websockets might be a show-stopper. It's 2019 ffs, get it together.

[nonchip]

@sci4me it's definitely possible using the openresty ecosystem, see also how i did it here using my own framework instead: https://gitlab.com/nonchip/lite-roller.nonchip.de/blob/master/apps/socket.moon

there's just no utilities in lapis for it yet. but if you manage to circumvent enough of lapis' HTTP and output handling code to be able to call resty.websocket.server\new without it interfering it should work.

[ryanford]

Verbal +1 and "me toos" contribute nothing to the thread. If you want to show your support add a :+1: in the appropriate place.

[eko234]

So, ws when?

[nonchip]

@eko234 judging by any other feature ever requested and then possibly implemented since @leafo launched itch.io: when that site needs it.

[Juniiorf]

• 1 for websockets

[AdamLearns]

There's some more context on the difficulty behind this feature in this Hacker News comment from @leafo.

[leafo]

Just want to note that if you are in Openresty you can use resty.websocket with no issues to "upgrade" the request to a websocket within the action handler. In this example, data is streamed over a websocket to the client over 10 seconds.

Things to note:

• use skip_render to avoid having Lapis try to write anything to the request response after handling the socket
• this is very bare bones interface, you are responsible for things like ping and pong, inter-client communication, duplex event processing. Openresty isn't the best candidate for stuff like this so your mileage may vary if you have a complex use case
• database connections are lazily assigned to a request on first query, and are only returned to the connection pool after the function exits

app:match("/websocket-test", function(self)
  local ws = require "resty.websocket.server"
  local server = assert(ws:new())
  for i = 1, 10 do
    if not server:send_text("hello world: " .. i) then
      -- if sending fails, collection is probably closed
      break
    end
    ngx.sleep(1)
  end
  server:send_close()
  return { skip_render =  true }
end)