An install that discovers a missing dependency halfway through has already made a directory, possibly
started a container and written a row, and then has to unwind — leaving the user with something that
neither works nor uninstalls. A 30ms check first is worth most of that.
Verified while writing this: nothing in scripts/ installs Docker, and nothing checks for it.
setup-dockers.sh invokes `docker compose` with no preflight, so a fresh host without Docker fails
partway through setup with a bare "command not found". Recorded in the design doc rather than fixed
here — the intended fix is a setup.sh per sidecar, which is also what a sidecar needs once it ships from
its own repository.
`docker compose version` is the probe, not `docker --version`: the latter passes with a dead daemon,
which is the failure people actually hit. "Not installed" and "daemon unreachable" are reported
separately because the remedies differ.
Checked per MODE, not per entry. A host without Docker can still install Photos by pointing at an Immich
somewhere else; refusing the whole entry is the over-strict check that makes people work around the
installer instead of using it.
Dropped `requires: 'docker'` from the catalogue type. Needing Docker is exactly "this entry can
provision", which `modes` already says, so declaring it twice invites the two to disagree. Derived by
needsDocker instead, and a test asserts the derivation matches every entry.
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
pastilhasandClaude Opus 5
7359867f7f