Redis2_pass with <host>:<port> from $args fail

[maxf3r]

I'm trying to address several redis instances, dispatching it on a host:port basis (one single backend location)

here my nginx.conf location
...
location /redis_backend {
internal;
set_unescape_uri $verb $arg_verb;
set_unescape_uri $key $arg_key;
set_unescape_uri $r_host $arg_host;
set_unescape_uri $r_port $arg_port;
redis2_query $verb $key;
redis2_pass $r_host:$r_port;
}
...

I call /redis_backend location from a lua like this:

....
r_instance["redis_host"] = '127.0.0.1'
r_instance["redis_port"] = '33001'
....
local res = ngx.location.capture (
"/redis_backend",
{ args =
{ verb = r_verb,
key = redis_key,
host = r_instance["redis_host"],
port = r_instance["redis_port"],
}
}
)
...

in nginx error log (i use the openresty suite ngx_openresty/1.0.10.44), I got this error
2012/04/07 19:25:03 [error] 11715#0: *1 redis2: upstream "127.0.0.1:33001" not found, client: 127.0.0.1, server: ....

I'm sure redis instance is up&running. I'm able to connect to her via redis-cli or, simply setting redis2_pass 127.0.0.1:33001;

ciao
massimo

[agentzh]

I'm terribly sorry for the delay! I don't know why I missed the email for this ticket :(

ngx_redis2 only supports nginx variables pointing to upstream names that are already defined. For example:

 upstream foo { server ...; }
 upstream bar { server ...; }

and then we can have

location = /api {
    set $target 'foo';
    redis2_pass $target;
}

That will work. But you cannot specify raw host names and port number in the nginx variable for redis2_pass.

It seems that you're already using Lua to access ngx_redis2, so it is now recommended to use the lua-resty-redis library which is much more flexible and much easier to use than issuing subrequests to locations configured by ngx_redis2:

https://github.com/agentzh/lua-resty-redis

Also, this library is usually more efficient ;)

Thanks!
-agentzh

[signals2]

--location = /api {
-- set $target 'foo';
-- redis2_pass $target;
--}

It seems this feature is not working any more with v0.11, the error.log always says:
[alert] 28236#0: *25 no upstream configuration

[agentzh]

@signals2 There has been a test case for this usage in ngx_redis2's test suite that keeps passing for long:

https://github.com/openresty/redis2-nginx-module/blob/master/t/sanity.t#L294

One common mistake is that you forget to define the named upstream {} blocks for all possible nginx variable values beforehand.

[signals2]

Finally I find the answer, it's not working when using out of one or multiple if conditions, for example:
if($arg_k)
{
redis2_query get $arg_k;
}
redis2_pass $arg_pool;

instead the following config is working:
if ($arg_k)
{
redis2_query get $arg_k;
redis2_pass $arg_pool;
}

maybe i'm using it in a wrong way?

thanks

[agentzh]

@signals2 Please avoid the use of the "if" directive. See http://wiki.nginx.org/IfIsEvil

Better use ngx_lua and lua-resty-redis for such things.

[signals2]

@agentzh thanks alot
in my simple case, it's more convinient with this module than lua-resty-redis lua module, the evil 'if' is really a big surprise:(