Add a key/value to Redis in Nginx - nginx

Question

I would like to communicate with redis from nginx, in order to store in lists which requests have been made on images especially on images not founds that are proxied on another server.
I installed OpenResty, in order to use redis2_query and redis2_pass commands.
Here is my nginx config :
location ~* \.(jpg|jpeg|gif|png)$ {
try_files $uri #imagenotfound;
redis2_query lpush founds $uri;
redis2_pass 127.0.0.1:6379;
}
location #imagenotfound {
proxy_pass http://imgdomain.com/$uri;
proxy_set_header Host imgdomain.com;
proxy_set_header Server imgdomain.com;
redis2_query lpush notfounds $uri;
redis2_pass 127.0.0.1:6379;
}
Every request i make returns an integer, and, as i understand, redis2_pass returns the result of the query. Is there anyway to not return this result and just execute the query?
If i remove the redis2_query and redis2_pass, the images are displayed correctly.
Thanks in advance for your help!

Answer 1

A solution that seems to work is to use Lua scripts with access_by_lua and the resty.redis module :
location ~* \.(jpg|jpeg|gif|png)$ {
try_files $uri #imagenotfound;
access_by_lua '
local redis = require "resty.redis"
local red = redis:new()
red:set_timeout(1000)
local ok, err = red:connect("127.0.0.1", 6379)
if not ok then
ngx.say("failed to connect: ", err)
return
end
ok, err = red:lpush("founds", ngx.var.uri)
if not ok then
ngx.say("failed to set founds: ", err)
return
end
';
}
location #imagenotfound {
proxy_pass http://imgdomain.com/$uri;
proxy_set_header Host imgdomain.com;
proxy_set_header Server imgdomain.com;
access_by_lua '
local redis = require "resty.redis"
local red = redis:new()
red:set_timeout(1000)
local ok, err = red:connect("127.0.0.1", 6379)
if not ok then
ngx.say("failed to connect: ", err)
return
end
ok, err = red:lpush("notfounds", ngx.var.uri)
if not ok then
ngx.say("failed to set notfounds: ", err)
return
end
';
}
If anyone has Lua skills and can tell me if it's the right way to do it, i would be glad to have his feedback!
Anyway, thanks for your help in comments.