How to workaround the lack of cosocket API at init context?

[Yan Gabriel Minário]

I’ve forked a Telegram Bot written in lua and decided to add webhook support using openresty: https://gitlab.com/Synko/GroupButler 

So far so good, but I’d like to do some initialization work before handling requests, like getting bot info from telegram API (/getMe), sending a message for the admin when the bot starts up (/sendMessage), load plugins (optional lua modules) etc. Most of these tasks require reaching the telegram servers from http, that means I can’t use resty.http (also getting ssl errors with this one but that’s another problem) to do these requisitions.

Currently I’m calling curl using os.execute, which is ugly to say the least.

[David Birdsong]

Use 'timer.at' to schedule the work to run in another coroutine.

If you search around, there should be examples. I think the resty consul lib might illustrate how.

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[Michal Cichra]

I'm working on API Gateway which needs to download configuration before accepting any work and I settled on calling `os.execute` to a helper script in libexec spawning `resty` with some lua to perform a request. 

I tried timer.at and using semaphore and resty.lock for synchronization, but none of those worked. 

[tokers]

cosocket can not be used in the phase like init_by_lua or init_worker_by_lua.

BTW, maybe you can use the lua socket lib?

[Yan Gabriel Minário]

So I ended up dropping init in favor of init_woker and using shared dict to “lock” the startup process to a single worker. It looks like this:

init_worker.lua:

local function bot_init()

--call things that use cosocket

end

local bot = ngx.shared.bot

local started = bot:get(‘started')

if not started then -- Check if no other worker has already run the startup process

bot:set(‘started’, luatz.time()) -- “Lock” so no other worker run this again

local ok, err = ngx.timer.at(0, bot_init) -- Create a 0 delay timer with init function

if not ok then

ngx.log(ngx.ERR, "failed to create timer: ", err)

return

end

end

[mci...@redhat.com]

Looks like this is worked on https://github.com/openresty/lua-nginx-module/issues/1020

Maybe express the interest there to bump the priority.