access_by_lua without proxy_pass

[Gaurav Saxena]

Hi All,

I am trying to setup a configuration where I am doing proxy_pass at one location. But, there are different locations that point at it. I want to add some validations before calling the particular location. I want to run basic check and then redirect the request to the main location. But, if I use rewrite, access_by_lua doesn't run. I did read about access_by_lua not being called for subrequests. But, if the first call directly hits a block with access_by_lua that should not be considered a subrequest. Is that understanding correct?

Example - 

server {
    listen 4000;
      location ~  ^/hello/world/(.*)$ {
        set $path $1;

        access_by_lua_block {
            ngx.log (ngx.NOTICE, "in Lua")
          
            ngx.exit(ngx.HTTP_INTERNAL_SERVER_ERROR)
          }

          

          rewrite ^ /$path last; # access_by_lua doesn't run
          proxy_pass http://google.com?q=$channel; # access_by_lua does run
      }

      location ~ foo {
        return 200 "bar";
      }
    }

curl localhost:4000/hello/world/foo 

200

bar

I would appreciate any insights here. 

[bjoe2k4]

rewrite runs before access phase, and since you rewrite to another location, you never reach the access phase for the first location. See: https://cloud.githubusercontent.com/assets/2137369/15272097/77d1c09e-1a37-11e6-97ef-d9767035fc3e.png

2 solutions:

1) use rewrite_by_lua and put your validation logic and rewrite logic there. no access_by_lua needed.
2) use access_by_lua and put your validation logic and rewrite logic there. no rewrite_by_lua needed.

[Gaurav Saxena]

Thanks a lot for the quick response and helpful information. I decided to go with 1.