Cbox vs ServerSideUp
Cbox vs ServerSideUp
serversideup/php is an excellent, mature project — if you evaluate it and it fits, use it with confidence. This page describes where the two projects genuinely differ, so you can pick based on what you actually need. Both are production-ready, both rebuild weekly with security patches, and both are maintained by teams that run them in production.
The short version
Choose ServerSideUp when you want a battle-tested, widely adopted PHP image with a large community, Alpine and Debian bases, Apache and FrankenPHP variants, and years of ecosystem content behind it.
Choose Cbox when you want a runtime control plane inside the container: supervised multi-process orchestration with dependency ordering, live capacity management for PHP-FPM, supervisor-owned readiness, metrics, and a release contract that separates behavior pinning from security patching.
At a Glance
| Cbox | ServerSideUp | |
|---|---|---|
| Process manager | Cbox Init (single Go binary: DAG dependencies, health-check-driven restarts, readiness, management API/CLI/TUI, Prometheus metrics) | S6 Overlay (proven, widely deployed init system) |
| PHP-FPM sizing | Boot-time calculation from cgroup limits + runtime autotuning (live per-worker PSS measurement, graceful pool resizing) | Static configuration via env vars |
| Health checks | Built-in, drive supervised restarts and readiness | Built-in (native health checks) |
| Variants | FPM, CLI, FPM+Nginx, standalone Nginx | FPM, CLI, FPM+Nginx, FPM+Apache, FrankenPHP |
| OS bases | Debian 12 | Debian, Alpine |
| PHP versions | 8.2–8.5 | 8.1–8.5 |
| Image tiers | 4 (Slim / Standard / Chromium / Dev), all with rootless variants | Base / Full per variant |
| Framework startup automation | Laravel, Symfony, WordPress auto-detected (permissions, scheduler, queues, Horizon, Reverb) | Laravel-focused (opt-in automations) |
| Version pinning | Rolling, release-channel (-v1: behavior pinned, security patches keep flowing), and immutable digests |
Rolling (weekly rebuilds) and immutable version pins |
| Observability | Prometheus metrics, structured JSON logs, OpenTelemetry-aware supervisor, fpm_tune_* capacity metrics |
Standard container logging |
| Community & maturity | Newer, smaller community | Large community, years of production use, extensive guides |
Where ServerSideUp is ahead
Be honest about this list before choosing Cbox:
- Maturity and ecosystem. More users, more tutorials, more Stack Overflow answers, more third-party content. That matters when onboarding a team.
- Alpine. Cbox is Debian-only by design (glibc compatibility); if you need musl-based images, ServerSideUp has them.
- Apache and FrankenPHP variants. Cbox deliberately concentrates on PHP-FPM + Nginx (see below) and does not offer either.
- PHP 8.1. Cbox starts at 8.2.
Where Cbox is ahead
- Runtime capacity management. ServerSideUp (like every other image) sets
pm.max_childrenstatically. Cbox seeds it from the container's actual cgroup memory/CPU limits at boot, then — optionally — measures live per-worker memory (PSS, which doesn't double-count shared OPcache) and resizes the pool at runtime via an atomic drop-in and graceful reload. No dropped connections, master PID unchanged. See Runtime PHP-FPM tuning. - A control plane, not just an init. Cbox Init supervises processes as a
dependency graph (queues wait for FPM, warmup hooks gate health checks),
owns container readiness (
/readyz,/livez, readiness file), exposes a management API/CLI/TUI for live scaling and reloads, and exports Prometheus metrics for all of it. - Behavior-pinned, security-patched tags. The
-v1release channel means "keep my runtime contract, keep patching the OS underneath" — a middle ground between rolling tags and immutable pins that age. See Tagging Strategy. - Broader framework automation. Symfony and WordPress get the same startup automation as Laravel.
- A Chromium tier. Browsershot/Dusk/PDF workloads without building a custom image.
On PHP-FPM vs FrankenPHP
Cbox intentionally does not chase FrankenPHP. The classic PHP-FPM + Nginx architecture still runs most of the PHP world, and Cbox's position is that it deserves to be operated properly: supervised, measured, right-sized, and reloaded gracefully. If you want FrankenPHP, ServerSideUp has a good story there today.
Sources
Comparison last verified 2026-09-05 against the ServerSideUp docs. If anything here is out of date, please open an issue — we intend this page to stay honest.