Conditional logging variable removed from kong access_log directive.

[willianmga]

I've been following along this article about how to conditionally log requests with kong.

I'm using Kong on docker
Kong version 3.0.0.2

Tried two approaches to achieve my goal, but no luck at all..

1st Approach -- Use the entire template from the article.

The template is the same proposed in the article, stored under /tpm/kong/custom.conf

# ---------------------
# custom_nginx.template
# ---------------------

worker_processes $; # can be set by kong.conf
daemon $;                     # can be set by kong.conf

pid pids/nginx.pid;                      # this setting is mandatory
error_log stderr $; # can be set by kong.conf



events {
    use epoll; # custom setting
    multi_accept on;
}

http {


    map $request_uri $keeplog {
        ~.+\@.+\..+ 0;
        ~/v1/invitation/ 0;
        ~/reset/v1/customer/password/token 0;
        ~/v2/verify 0;

        default 1;
    }
    log_format show_everything '$remote_addr - $remote_user [$time_local] '
        '$request_uri $status $body_bytes_sent '
        '"$http_referer" "$http_user_agent"';

    include 'nginx-kong.conf';
}

with this

KONG_PROXY_ACCESS_LOG=/dev/stdout show_everything if=$keeplog

When trying to run kong using the template got the following error:

kong start --nginx-conf /tpm/kong/custom.conf
Error: nginx configuration is invalid (exit code 1):
nginx: [emerg] "worker_processes" directive invalid value in /usr/local/kong/nginx.conf:8
nginx: configuration file /usr/local/kong/nginx.conf test failed


  Run with --v (verbose) or --vv (debug) for more details

The template is still the same, though

kong@3ae465af0764:/tmp/kong$ cat /usr/local/kong/nginx.conf
# ---------------------
# custom_nginx.template
# ---------------------

worker_processes $;
daemon $;

pid pids/nginx.pid; # this setting is mandatory
error_log stderr $;

events {
    use epoll; # custom setting
    multi_accept on;
}

http {

    map $request_uri $keeplog {
        ~.+\@.+\..+ 0;
        ~/v1/invitation/ 0;
        ~/reset/v1/customer/password/token 0;
        ~/v2/verify 0;
        default 1;
    }

    log_format show_everything '$remote_addr - $remote_user [$time_local] '
        '$request_uri $status $body_bytes_sent '
        '"$http_referer" "$http_user_agent"';

    include 'nginx-kong.conf';

QUESTION: Why is this happening? Kong should be able to start without complaining about worker_processes, no?

2nd Approach -- Partial file + nginx_http_include

I then moved on to try just include that on the template.

So my conf when to this

    map $request_uri $keeplog {
        ~.+\@.+\..+ 0;
        ~/v1/invitation/ 0;
        ~/reset/v1/customer/password/token 0;
        ~/v2/verify 0;
        default 1;
    }

    log_format show_everything '$remote_addr - $remote_user [$time_local] '
        '$request_uri $status $body_bytes_sent '
        '"$http_referer" "$http_user_agent"';

And i passed the following env var

KONG_PROXY_ACCESS_LOG=/dev/stdout show_everything if=$keeplog
KONG_NGINX_HTTP_INCLUDE=/tmp/kong/custom.conf

Then whatever request i send is not logged, regardless of pattern.

I even tried to strip it down to just the following, but no luck at all..

    map $request_uri $keeplog {
        default 1;
    }

    log_format show_everything '$remote_addr - $remote_user [$time_local] '
        '$request_uri $status $body_bytes_sent '
        '"$http_referer" "$http_user_agent"';

If i remove the if=$keeplog from proxy_access_log then it logs, though.

KONG_PROXY_ACCESS_LOG=/dev/stdout show_everything
KONG_NGINX_HTTP_INCLUDE=/tmp/kong/custom.conf

LAST BUT NOT LEAST

I noticed that on both approaches the proxy_access_log directive is leaving the if empty, not including the $keeplogs, like this:

cat nginx-kong.conf

server {
    {omitted...}

    access_log /dev/stdout  show_everything if=;
    error_log  /dev/stderr notice;

    {omitted...}

Any idea how on how to make it log condittionally ?

I'd personally prefer the second approach, since i think it would require less configuration changes, simply adding exactly what i need.

Thank you in advance!

[willianmga]

Case closed.

The variable keeplog wasn't being escaped on docker.

noticed that because of the warning

docker compose up                                                                                                                                                                                 
WARN[0000] The "keeplog" variable is not set. Defaulting to a blank string.

Fixed by escaping it using $$, like that

KONG_PROXY_ACCESS_LOG=/dev/stdout liferay_log_format if=$$keeplog

[hwlee96]

Was this using the first of second approach described?
Thanks!

[willianmga]

ended up using the second approach, but it should work for both