Access log to output plugin variables

[MUI-Pop]

I have few metadata as variables in plugin that need to be outputted in kong's access log. What is the best way to share the variable between plugin and kong access log ?

[hanshuebner]

Hello @MUI-Pop,

it is difficult to say what the best way is as that depends on your environment and deployment model. If you need to change the format of the access_log file which is written by nginx, then you'll need to work with a custom nginx configuration template, define the new variables and the access log format to use those variables, and then set the variables from your plugin in ngx.ctx. This approach is a little fiddly, however, in particular as you'll need to make sure that your custom templates keeps working across upgrades.

If you have a little more freedom with respect to how your access log is written, you could use a custom plugin to write the access log in the format that you require. That plugin could then access ngx.ctx to retrieve whatever information has been left there by your other plugin, or your other plugin could use kong.log.set_serialize_value() to put information into the log.serialize() return value.

Does this help?

[chobits]

hi @MUI-Pop I have marked this as answer, could you check it?

[MUI-Pop]

Thank you @hanshuebner. We are using the access_log nginx descriptor, in this case using ngx.ctx for passing data seems the way.

[MUI-Pop]

Commented too early, looks like ngx.ctxcannot be interpolated in the access log, hence I declared a ngx.var and referred it in access log.