[bitnami/nginx] Add worker_processes env var

[jhthompson]

Description of the change

Add a NGINX_WORKER_PROCESSES environment variable to control the value of the Nginx worker_processes directive.

Benefits

Ability to better control resource usage

Nginx's worker_processes auto creates too many worker processes in certain deployments. This change provides an easy hook to manually set the number to a more sensible value. From a currently open issue on Nginx itself:

Currently, if one uses worker_processes auto;, nginx uses sysconf(_SC_NPROCESSORS_ONLN) to detect the number of available processes.

In environments, such as Kubernetes or OpenShift, this causes issues, as it returns the cores available to the system and not the actual services available to the service.

This is a solved problem in the docker-nginx image by providing an entrypoint script to "tune" the value to something more appropriate, but adding a similar approach here feels heavy-handed.

Corrects existing documentation

It is not possible to override worker_processes via the listed method in the Readme, as Nginx errors with a "duplicate directive" since it ends up being present twice.

Possible drawbacks

If NGINX_WORKER_PROCESSES is currently set in any deployments that use this image, there may be unexpected behavior.

Applicable issues

n/a

Additional information

Various issues across several Nginx projects are related to this:

• Worker Processes (auto) doesn't honor cgroup allocations kubernetes/ingress-nginx#2948
• nginx start can't get cpu limit and change worker_processes numbers nginx/docker-nginx#472
• Make worker_processes cgroup-Compatible nginx/nginx#855

[jhthompson]

Some outputs from my local testing (if relevant). All commands ran from bitnami/nginx/1.29/debian-12):

Building the image locally:

docker build -t nginx-local:$(git rev-parse --short HEAD) --build-arg TARGETARCH=amd64 .

No env var

docker run nginx-local:80ceba9418a   
nginx 20:28:22.37 INFO  ==> 
nginx 20:28:22.37 INFO  ==> Welcome to the Bitnami nginx container
nginx 20:28:22.37 INFO  ==> 
nginx 20:28:22.38 INFO  ==> ** Starting NGINX setup **
nginx 20:28:22.40 INFO  ==> Validating settings in NGINX_* env vars
Certificate request self-signature ok
subject=CN = example.com
nginx 20:28:23.91 INFO  ==> No custom scripts in /docker-entrypoint-initdb.d
nginx 20:28:23.92 INFO  ==> Initializing NGINX
realpath: /bitnami/nginx/conf/vhosts: No such file or directory
nginx 20:28:23.96 INFO  ==> ** NGINX setup finished! **

nginx 20:28:23.98 INFO  ==> ** Starting NGINX **

(from running container):

nginx -T
nginx: the configuration file /opt/bitnami/nginx/conf/nginx.conf syntax is ok
nginx: configuration file /opt/bitnami/nginx/conf/nginx.conf test is successful
# configuration file /opt/bitnami/nginx/conf/nginx.conf:
# Based on https://www.nginx.com/resources/wiki/start/topics/examples/full/#nginx-conf
# user              www www;  ## Default: nobody

worker_processes  auto; # <------------------- relevant line here
error_log         "/opt/bitnami/nginx/logs/error.log";
pid               "/opt/bitnami/nginx/tmp/nginx.pid";

include  "/opt/bitnami/nginx/conf/context.d/main/*.conf";
# ... more below ...

With valid env var

docker run -e NGINX_WORKER_PROCESSES=1 nginx-local:80ceba9418a
nginx 20:33:37.26 INFO  ==> 
nginx 20:33:37.26 INFO  ==> Welcome to the Bitnami nginx container
nginx 20:33:37.27 INFO  ==> 
nginx 20:33:37.27 INFO  ==> ** Starting NGINX setup **
nginx 20:33:37.30 INFO  ==> Validating settings in NGINX_* env vars
Certificate request self-signature ok
subject=CN = example.com
nginx 20:33:41.25 INFO  ==> No custom scripts in /docker-entrypoint-initdb.d
nginx 20:33:41.25 INFO  ==> Initializing NGINX
realpath: /bitnami/nginx/conf/vhosts: No such file or directory
nginx 20:33:41.30 INFO  ==> ** NGINX setup finished! **

nginx 20:33:41.32 INFO  ==> ** Starting NGINX **

(from running container):

nginx -T
nginx: the configuration file /opt/bitnami/nginx/conf/nginx.conf syntax is ok
nginx: configuration file /opt/bitnami/nginx/conf/nginx.conf test is successful
# configuration file /opt/bitnami/nginx/conf/nginx.conf:
# Based on https://www.nginx.com/resources/wiki/start/topics/examples/full/#nginx-conf
# user              www www;  ## Default: nobody

worker_processes  1; # <------------------- relevant line here
error_log         "/opt/bitnami/nginx/logs/error.log";
pid               "/opt/bitnami/nginx/tmp/nginx.pid";

include  "/opt/bitnami/nginx/conf/context.d/main/*.conf";
# ... more below ...

With invalid env var

docker run -e NGINX_WORKER_PROCESSES=aut nginx-local:80ceba9418a
nginx 20:35:31.23 INFO  ==> 
nginx 20:35:31.23 INFO  ==> Welcome to the Bitnami nginx container
nginx 20:35:31.24 INFO  ==> 
nginx 20:35:31.24 INFO  ==> ** Starting NGINX setup **
nginx 20:35:31.26 INFO  ==> Validating settings in NGINX_* env vars
nginx 20:35:31.26 ERROR ==> The allowed values for NGINX_WORKER_PROCESSES are: auto or a positive integer

docker run -e NGINX_WORKER_PROCESSES=-2 nginx-local:80ceba9418a
nginx 20:35:46.13 INFO  ==> 
nginx 20:35:46.13 INFO  ==> Welcome to the Bitnami nginx container
nginx 20:35:46.13 INFO  ==> 
nginx 20:35:46.14 INFO  ==> ** Starting NGINX setup **
nginx 20:35:46.16 INFO  ==> Validating settings in NGINX_* env vars
nginx 20:35:46.16 ERROR ==> The allowed values for NGINX_WORKER_PROCESSES are: auto or a positive integer

[jhthompson]

@fmulero @carrodher sorry for the ping! Just checking in to see if anyone has had a chance to look at this yet, and if there's anything I should add/remove/change.

[jhthompson]

@fmulero @carrodher sorry for another ping - is there anything I can do to help move things along on this?