Any way to set an nginx variable in Lua by retrieving over http?

igor.clark · 2015-03-11T20:25:11+00:00

Hello! On Wed, Mar 11, 2015 at 6:14 AM, Wang Chunsheng wrote: > hi,agentzh , i have writen this for add_server(upstream) ,but have some > Confusion&#x...

Any way to set an nginx variable in Lua by retrieving over http?

igor.clark

Hello nginx-lua folks,

I'd like to capture the output of a remote REST API call and set the result in an nginx variable.

I have a Lua module:function which talks to the API and retrieves the content correctly, but it seems I can't call it from a set_by_lua block, as the necessary socket I/O code (tcp()) is disabled in 'set_by_lua*'.

Is there a way to do this? Maybe not with 'set_by_lua', but is there some mechanism whereby I can get Lua to retrieve a value and set it as an nginx variable?

Seems like a fairly reasonable thing to want to do, but I could be missing something obvious :-)

Thanks for your help,
Igor

agentzh

Hello!

On Wed, Mar 11, 2015 at 5:25 AM, Igor Clark wrote:
> I'd like to capture the output of a remote REST API call and set the result
> in an nginx variable.
>
> I have a Lua module:function which talks to the API and retrieves the
> content correctly, but it seems I can't call it from a set_by_lua block, as
> the necessary socket I/O code (tcp()) is disabled in 'set_by_lua*'.

Don't use set_by_lua*, use rewrite_by_lua* or access_by_lua* instead.
Here is an example for such things:

    https://github.com/openresty/nginx-eval-module#use-lua-instead

The sample there uses ngx.location.capture(), which can also be
replaced by the cosocket API calls or any other (nonblocking) I/O
calls.

Regards,
-agentzh

igor.clark

Ah, excellent. I hadn't thought of using a rewrite without rewriting the URL. This is great, it does exactly what I need. Thank you!

Also thanks for ngx_lua in general, it seems pretty amazing :-)

Best
Igor

On Wednesday, March 11, 2015 at 9:42:18 PM UTC, agentzh wrote:

Hello!

On Wed, Mar 11, 2015 at 5:25 AM, Igor Clark wrote:
> I'd like to capture the output of a remote REST API call and set the result
> in an nginx variable.
>
> I have a Lua module:function which talks to the API and retrieves the
> content correctly, but it seems I can't call it from a set_by_lua block, as
> the necessary socket I/O code (tcp()) is disabled in 'set_by_lua*'.

Don't use set_by_lua*, use rewrite_by_lua* or access_by_lua* instead.
Here is an example for such things:

https://github.com/openresty/nginx-eval-module#use-lua-instead

The sample there uses ngx.location.capture(), which can also be
replaced by the cosocket API calls or any other (nonblocking) I/O
calls.

Regards,
-agentzh