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runtime ships a multi-arch image for each supported PHP minor. site-template runs a nightly compat-matrix that confirms each PHP × WP combination still composes cleanly. This page is the source of truth for which combinations are blessed.

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Supported combinations

PHP < 8.3 is EOL or near-EOL upstream — out of scope. WordPress < 6.8 is below the floor we commit to support. The compat-matrix workflow runs on every PR to site-template plus nightly at 06:00 UTC, so any regression introduced by an upstream WP point release within ~6.8.0 / ~6.9.0 is caught within 24 hours.

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Tag schema

runtime publishes a multi-arch manifest list (linux/amd64 + linux/arm64) under each of these tags: The unprefixed :v<W.Z> channel exists so consumers who don’t care which PHP they’re on can pin a release without encoding the default. The default PHP is 8.3 — see Default-PHP cadence.

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Picking a PHP

site-template’s Dockerfile defaults the runtime base to the default PHP:
To opt into a different PHP, either pin it in your fork’s Dockerfile:
…or override per-build:
Your site’s CI (build.yml) honours the Dockerfile default; per-build overrides only affect the invocation that sets them.
To exercise your actual site code under a non-default PHP before flipping it, run FP_RUNTIME_VERSION=php8.4 make build locally. The compose harness picks up the override.

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Picking a WordPress minor

WordPress core is composer-installed at site-build time, gated by the roots/wordpress constraint in your fork’s composer.json:
^6.8 admits both 6.8.x and 6.9.x; composer install resolves to the highest matching point release at build time. To lock onto a specific minor:
~6.9.0 admits patch releases (6.9.1, 6.9.2, …) but not 6.10. Useful when an upstream minor introduces a regression for your stack and you want a stable hold-line until it’s fixed.

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Default-PHP cadence

The unprefixed :v<W.Z> channel always points at the default PHP, currently 8.3. The default is bumped deliberately — typically ~6 months after a new PHP minor reaches upstream-stable status, long enough for early ecosystem incompatibilities to surface and be patched. A default-PHP bump is a coordinated PR across runtime (the DEFAULT_PHP env in build.yml) and this page. site-template forks do not auto-bump; each site pins its own PHP via the FP_RUNTIME_VERSION build arg.

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What’s next

runtime

Build args, env vars, and the cache-invalidation contract.

Upgrade flow

git tag → CI → helm upgrade per environment.