Disable systemd rate limiting for PHP-FPM to prevent installation fai…

[klemenza]

Fix PHP-FPM installation failures by disabling systemd rate limiting

Problem

On first provision, the PHP extension installation task fails with:

• Job for php8.3-fpm.service failed.
• Start request repeated too quickly.
• Failed with result 'start-limit-hit'.
• dpkg: error processing package php8.3-fpm (--configure)

This only happens on first provision because:

1. Trellis installs multiple PHP extensions in a loop (php8.3-bcmath, php8.3-cli, php8.3-curl, etc.)
2. Each extension installation triggers php-fpm to restart via dpkg post-install hooks
3. Systemd's default rate limit is 5 starts per 10 seconds
4. With 10+ extensions installing, php-fpm hits this limit
5. Systemd blocks further restarts and dpkg fails

On subsequent provisions, extensions are already installed (no restarts triggered), so the issue doesn't occur.

Solution

Add a systemd override during bootstrap that disables rate limiting for php8.3-fpm.service:

mkdir -p /etc/systemd/system/php8.3-fpm.service.d
cat > /etc/systemd/system/php8.3-fpm.service.d/override.conf << 'EOF'
[Unit]
StartLimitIntervalSec=0
EOF

Setting StartLimitIntervalSec=0 tells systemd to never enforce rate limits on this service, allowing unlimited restarts during the package installation loop.

Why WSL-specific

This is particularly problematic in WSL2 because:

Fresh distros are bootstrapped and provisioned in one flow
The entire stack (Ansible + PHP + all extensions) installs in minutes
The rapid-fire dpkg operations hit systemd limits that production servers never see (they install packages gradually over time)

Testing

Tested on Windows 11 with WSL2 Ubuntu 24.04. PHP 8.3 and all extensions now install successfully on first provision without start-limit-hit errors.