#1974 closed defect (invalid)

Custom variable not written to access_log when nginx.status is 400

Reported by: bxn-ts@… Owned by:
Priority: minor Milestone:
Component: nginx-core Version: 1.19.x
Keywords: variable, log, status Cc: bxn-ts@…
uname -a: Linux www-dev-1 4.19.0-8-cloud-amd64 #1 SMP Debian 4.19.98-1+deb10u1 (2020-04-27) x86_64 GNU/Linux
nginx -V: nginx version: nginx/1.18.0
built by gcc 8.3.0 (Debian 8.3.0-6)
built with OpenSSL 1.1.1d 10 Sep 2019
TLS SNI support enabled
configure arguments: --prefix=/etc/nginx --sbin-path=/usr/sbin/nginx --modules-path=/usr/lib/nginx/modules --conf-path=/etc/nginx/nginx.conf --error-log-path=/var/log/nginx/error.log --http-log-path=/var/log/nginx/access.log --pid-path=/var/run/nginx.pid --lock-path=/var/run/nginx.lock --http-client-body-temp-path=/var/cache/nginx/client_temp --http-proxy-temp-path=/var/cache/nginx/proxy_temp --http-fastcgi-temp-path=/var/cache/nginx/fastcgi_temp --http-uwsgi-temp-path=/var/cache/nginx/uwsgi_temp --http-scgi-temp-path=/var/cache/nginx/scgi_temp --user=nginx --group=nginx --with-compat --with-file-aio --with-threads --with-http_addition_module --with-http_auth_request_module --with-http_dav_module --with-http_flv_module --with-http_gunzip_module --with-http_gzip_static_module --with-http_mp4_module --with-http_random_index_module --with-http_realip_module --with-http_secure_link_module --with-http_slice_module --with-http_ssl_module --with-http_stub_status_module --with-http_sub_module --with-http_v2_module --with-mail --with-mail_ssl_module --with-stream --with-stream_realip_module --with-stream_ssl_module --with-stream_ssl_preread_module --with-cc-opt='-g -O2 -fdebug-prefix-map=/data/builder/debuild/nginx-1.18.0/debian/debuild-base/nginx-1.18.0=. -fstack-protector-strong -Wformat -Werror=format-security -Wp,-D_FORTIFY_SOURCE=2 -fPIC' --with-ld-opt='-Wl,-z,relro -Wl,-z,now -Wl,--as-needed -pie'


TL;DR: A custom variable is not written to my access log file when the server returns the status error 400.

The server has a few custom variables set and is configured to use client certification verification. These custom variables are also used in a custom log format. When the server is contacted without providing a client certificate, it returns 400 which is expected.
The issue I'm facing is that while this creates a log entry in the access log file, the custom variable is not part of it. The variables are logged to the access log when it's a different status code, e.g. 200 or 301.

Change History (1)

comment:1 by Maxim Dounin, 10 months ago

Resolution: invalid
Status: newclosed

When a 400 error occurs before request processing starts - for example, due to missing client certificate - no processing of the request happens, including no set directives executed. As long as your custom variables rely on the set directives or other server-level rewrite module directives, it is expected they won't be properly set when logging 400 errors.

If you want variables to be usable when logging early-generated errors, consider using map instead to provide custom variables.

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