Run Custom S6 Script as root

[papoms]

I am successfully using custom s6 services to run stuff in the container.

Now with the switch from v2 -> v3 i am facing an issue where i used a oneshot script to install something as root (in v2).

How would i "sudo" here to install as root?

/etc/s6-overlay/s6-rc.d/install-software-x

#!/command/with-contenv bash
/install_xyz.sh

[jaydrogers]

sudo is not available by default in our images. So I see two options here:

1. Run our images as root (Add USER root) at the end of your image (like we do for the ci step here https://serversideup.net/open-source/docker-php/docs/guide/migrating-from-v2-to-v3#cicd)
2. Install and configure sudo and grant www-data to do root things (which might be worse than just running the image as root because at least root will start services as www-data and anonymous users will not have access to do root things)

Hope this helps!

[LorenzoRogai]

@jaydrogers on the latest images, this error appears when USER root is left at the end of the Dockerfile

Is this normal? The image still proceeds to boot and run normally afterward

/package/admin/s6-overlay/libexec/preinit: info: /run belongs to uid 33 instead of 0 - fixing it

[29-Jan-2026 15:20:49] ALERT: [pool www] user has not been defined

[29-Jan-2026 15:20:49] ERROR: failed to post process the configuration

[29-Jan-2026 15:20:49] ERROR: FPM initialization failed

[jaydrogers]

This message is okay:

/package/admin/s6-overlay/libexec/preinit: info: /run belongs to uid 33 instead of 0 - fixing it

It's just a warning and it fixes itself.

These I cannot replicate:

[29-Jan-2026 15:20:49] ALERT: [pool www] user has not been defined
[29-Jan-2026 15:20:49] ERROR: failed to post process the configuration
[29-Jan-2026 15:20:49] ERROR: FPM initialization failed

Command to replicate:

docker run --rm --pull always --user root serversideup/php:8.5-fpm-nginx

Results:

8.5-fpm-nginx: Pulling from serversideup/php
Digest: sha256:14724e05e959da090b061ed445d0f73568bb5e69f1b1b3a694f931a619a964b3
Status: Image is up to date for serversideup/php:8.5-fpm-nginx

--------------------------------------------------------------------
 ____                             ____  _     _        _   _
/ ___|  ___ _ ____   _____ _ __  / ___|(_) __| | ___  | | | |_ __
\___ \ / _ \  __\ \ / / _ \  __| \___ \| |/ _` |/ _ \ | | | |  _ \
 ___) |  __/ |   \ V /  __/ |     ___) | | (_| |  __/ | |_| | |_) |
|____/ \___|_|    \_/ \___|_|    |____/|_|\__,_|\___|  \___/| .__/
                                                            |_|

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-------------------------------------
ℹ️ Container Information
-------------------------------------
📦 Versions
• Image:         v4.3.0-21389458876
• PHP:           8.5.2
• OS:            Debian GNU/Linux 13 (trixie)

👤 Container User
• User:          root
• UID:           0
• GID:           0

⚡ Performance
• OPcache:       ❌ Disabled
• Memory Limit:  256M
• Upload Limit:  100M

🔄 Runtime
• Docker CMD:     /init

👉 [NOTICE]: Improve PHP performance by setting PHP_OPCACHE_ENABLE=1 (recommended for production).
ℹ️ NOTICE (generate-ssl): SSL mode is off, so we won't generate a self-signed SSL key pair.
(init-webserver-config): Processing /etc/nginx/nginx.conf.template → /etc/nginx/nginx.conf...
(init-webserver-config): Processing /etc/nginx/site-opts.d/http.conf.template → /etc/nginx/site-opts.d/http.conf...
(init-webserver-config): Processing /etc/nginx/site-opts.d/https.conf.template → /etc/nginx/site-opts.d/https.conf...
(init-webserver-config): Processing /etc/nginx/sites-available/ssl-full.template → /etc/nginx/sites-available/ssl-full...
ℹ️ NOTICE (init-webserver-config): Enabling NGINX site with SSL "off"...
/package/admin/s6-overlay/libexec/preinit: info: /run belongs to uid 33 instead of 0 - fixing it
[29-Jan-2026 16:52:26] NOTICE: fpm is running, pid 112
[29-Jan-2026 16:52:26] NOTICE: ready to handle connections
✅ NGINX + PHP-FPM is running correctly.

[LorenzoRogai]

@jaydrogers it happens when using docker-php-serversideup-s6-init

FROM serversideup/php:8.4-fpm-nginx

ENV S6_CMD_WAIT_FOR_SERVICES=1

ENV AUTORUN_ENABLED "true"
ENV AUTORUN_LARAVEL_MIGRATION "false"
ENV PHP_OPCACHE_ENABLE "1"

ENV PHP_MEMORY_LIMIT "4096M"

# Register custom startup scripts
COPY --chmod=755 ./entrypoint.d/ /etc/entrypoint.d/

# Change to root, so we can do root things
USER root

# As root, run the docker-php-serversideup-s6-init script
RUN docker-php-serversideup-s6-init