Setting a response from a rewrite_by_lua directive

yannick.tapsoba · 2014-11-26T06:00:00+00:00

The ngx_http_finalize_request seems to have fixed the problem. Thank you for pointing me in the correct direction.On Tuesday, November 25, 2014 4:04:33...

Setting a response from a rewrite_by_lua directive

yannick.tapsoba

I have a rewrite_by_lua_file directive where I lookup a key supplied as a header in the original request, in a shared lookup table. If found, I pass as a header the value mapped to the original key. If not, I return a specific status code.

So in my nginx.conf I have:

location /start
{
   rewrite_by_lua_file key_lookup.lua;
   proxy_pass http://127.0.0.1:8080/start;
}

And my key_lookup.lua is:

local cjson = require("cjson")
local headers = ngx.req.get_headers()
local key = headers["X-KEY-HEADER"]

if key then
   local value = ngx.shared.lookuptable[key]
   if value then
      ngx.req.set_header("X-VALUE-HEADER", tostring(value))
   else
      ngx.log(ngx.ERR, "Unable to find value for key " .. tostring(key))
      ngx.status = ngx.HTTP_UNAUTHORIZED
      ngx.say(cjson.encode({error = {code = "401 Unauthorized", cause = "10000"}}))
      ngx.exit(ngx.HTTP_UNAUTHORIZED)
   end
else
   ngx.log(ngx.ERR, "X-KEY-HEADER not specified")
   ngx.exit(ngx.HTTP_UNAUTHORIZED)
end

So I am trying to set the response body to a specific JSON content when I return 401 Unauthorized, with no luck (the status code returned is what I expect, but the response body is empty). I have also tried using ngx.print.

Is there another way to achieve this?

agentzh

Hello!

On Tue, Nov 25, 2014 at 2:00 PM, tripledot wrote:
> So I am trying to set the response body to a specific JSON content when I
> return 401 Unauthorized, with no luck (the status code returned is what I
> expect, but the response body is empty). I have also tried using ngx.print.

I tried the following minimal example on my side with the latest
OpenResty (1.7.7.1 RC1):

    location = /t {
        rewrite_by_lua '
          ngx.status = ngx.HTTP_UNAUTHORIZED
          ngx.say("hello world")
          ngx.exit(ngx.HTTP_UNAUTHORIZED)
        ';
    }

And it works as expected:

    $ curl -i localhost:8080/t
    HTTP/1.1 401 Unauthorized
    Server: openresty/1.7.7.1rc1
    Date: Tue, 25 Nov 2014 23:03:05 GMT
    Content-Type: text/plain
    Transfer-Encoding: chunked
    Connection: keep-alive

    hello world

If you still believe there is a bug, please try constructing a
standalone and minimal example that can reproduce the problem on
others' boxes.

BTW, your complicated code example does not call ngx.status = 401 and
ngx.print/ngx.say on *every* code path calling ngx.exit(401).

Regards,
-agentzh