Ensure nginx worker processes respects docker limits

[felipecrs]

Refs #10969 (comment)

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[felipecrs]

I tested by starting the devcontainer, then checking the contents of /usr/local/nginx/conf/nginx.conf.

You can limit the cpus in docker-compose.yaml with:

services:
  devcontainer:
    deploy:
      resources:
        limits:
          cpus: '2'

[felipecrs]

@NickM-27 made the changes, also tested them.

BTW I just noticed this:

# we need to catch any errors because sed will fail if user has bind mounted a custom nginx file

How about we avoid calling set_worker_processes if the nginx file is mounted? I can do the changes.

[NickM-27]

I think it might be preferable to leave it as is. Changes were made so users shouldn't need to bind mount this file anymore, but in any case probably best to catch any error that occurs so it doesn't stop frigate from starting.

[felipecrs]

It would be very unexpected to have errors happening at that command though. I have these changes ready:

function set_worker_processes() {
    if mountpoint -q /usr/local/nginx/conf/nginx.conf; then
        echo "[INFO] NGINX configuration is mounted. Skipping worker_processes calculation..." >&2
        return
    fi

    # Capture number of assigned CPUs to calculate worker processes
    local cpus
    cpus=$(get_cpus)
    if [[ "${cpus}" -gt 4 ]]; then
        cpus=4
    fi

    echo "[INFO] Setting NGINX worker_processes to ${cpus}..." >&2
    sed -i "s/worker_processes auto;/worker_processes ${cpus};/" /usr/local/nginx/conf/nginx.conf
}

Let me know in case you change your mind.