ngx_lua module and POST request

osa_ru · 2016-08-10T23:58:16+00:00

Hello! On Tue, Aug 9, 2016 at 10:35 AM, Mike Lowry wrote: > In attempting to build an application within the OpenResty environment, I am > still a bit...

ngx_lua module and POST request

osa_ru

Hello,

I have a question about the POST request processing with ngx_lua.
In my case a body of a POST request contains a guess about a backned,
where the request must be processed.  So, I need to find this guess
and then process the whole requst without of any modification on
a backend.

So, I've tried to resolve this case with content_by_lua_block.  Since
the POST request contains a form with the data, I do

location /bla/bla/bla {

    set $backend '';

    content_by_lua_block {
        local upload = require "resty.upload"
        local chunk_size = 4096

        local form, err = upload:new(chunk_size)
        if not form then
            ngx.log(ngx.ERR, "failed to new upload: ", err)
            ngx.exit(500)
        end

        while true do
        -- get a header
            if typ == "header" then
            end
        --  ...
        -- get a part of the body
            if typ == "body" then
        --  ...
            end
        -- check res with ngx.say(res) output and it works
            if typ == "eof" then
                break
            end
        end
        ngx.var.backend = res
    }

    proxy_pass http://$backed;
}

At the end of the block I've tried to add ngx.var.backend variable
to expect it right after the content_by_lua_block, but it's empty.

Looks like I did something wrong?
Could you please recommend how can I resolve this case?

Thanks in advance.

--
Sergey A. Osokin

rpaprocki

Hi,

On Tue, Aug 9, 2016 at 9:56 AM, Sergey A. Osokin <o...@freebsd.org.ru> wrote:

Hello,

I have a question about the POST request processing with ngx_lua.
In my case a body of a POST request contains a guess about a backned,
where the request must be processed. So, I need to find this guess
and then process the whole requst without of any modification on
a backend.

So, I've tried to resolve this case with content_by_lua_block. Since
the POST request contains a form with the data, I do

You can't have both a content_by_lua handler and a proxy_pass directive in the same scope. The Lua phase handler will override proxy_pass. This is documented at 'https://github.com/openresty/lua-nginx-module#content_by_lua'. Might be better to do your checking in an earlier handler such as rewrite or access?

Alternatively, you can simplify this process by selecting your load balancer with balancer phase handler (https://github.com/openresty/lua-resty-core/blob/master/lib/ngx/balancer.md).