phpfpm module does not respect config.services.phpfpm.pools.<name>.user

[aftix]

Describe the bug

In the phpfpm module, there are the options userand group under services.phpfpm.pools.<name>. However, the module creates a systemd service for the pool that runs as root, ignoring these options.

Steps To Reproduce

Steps to reproduce the behavior:

1. Create a phpfpm pool using the nixos module on the nixos-unstable branch
2. The resulting service file does not specify User=or Group=

Expected behavior

I expect the phpfpm pool services created to run as the configured user and group and not root.

Additional context

Notify maintainers

@aanderse
@drupol
@Ma27
@talyz

Metadata

 - system: `"x86_64-linux"`
 - host os: `Linux 6.6.21-hardened1, NixOS, 24.05 (Uakari), 24.05.20240517.4a6b83b`
 - multi-user?: `yes`
 - sandbox: `yes`
 - version: `nix-env (Nix) 2.18.2`
 - nixpkgs: `/etc/nixpkgs/channels/nixpkgs`

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[aanderse]

this is by design

php-fpm runs the master process as root and then spawns child processes as the specified user and group values