The installer knew one distribution: Debian, with docker, on a new enough
release. Everything else it would have offered and then failed at.
Three facts now decide what the matrix offers, and each is read from the
machine rather than assumed:
- The container runtime. Docker where the machine has one, podman on the Red
Hat family, which ships no docker at all. Both go through the same compose
plugin: compose speaks the Docker API and podman serves it, so there is one
compose file and one deployment path, not two. Telling a Fedora operator to
add Docker's own repository to a machine that already has a container
runtime would have been the wrong trade.
- glibc. The server binary is downloaded, not built here, and it is linked
against 2.39. Rocky 9 (2.34), Debian 12 and Ubuntu 22.04 cannot run it, so
the host shape is refused there with the version found and the container
shape named as the answer -- rather than installing a file that cannot
start.
- The operating system itself. This compiles for macOS and Windows because Go
compiles anything, and on either it would read no os-release, find no
systemd, and describe a machine that does not exist. It now says what it is
and exits.
Two bugs the other distributions found, both of which Debian could not have:
- The survey reported the first thing in the way and stopped, so on Fedora it
asked to start podman.socket, and then -- having done it -- asked for the
compose plugin. Needs are named now, not described, and reported together.
- apply used the survey taken before dependencies were installed, so on a
machine that had no runtime at all it installed podman and then reached for
docker. It re-surveys after resolving, and stops if containers still are
not usable.
The lab takes DISTRO now: debian13, debian12, ubuntu2404, fedora, rocky9,
arch, each with its own disk and ssh port so several can be up at once. The
cases no longer say "docker" either. install-local passes on Debian 13,
Fedora 43 and Rocky 9 -- 20 checks each, ending with a sign-in to the webmail
the installer put there.
The first two pieces of the installer, and deliberately the two that change
nothing: what this machine is, and what would happen to it.
The survey is the floor under every later choice -- a component can only
offer a container shape if Docker answers for this user, or a host shape on
a systemd machine with what that shape needs. It reports what it could not
establish as unknown rather than guessing: an unprivileged probe of port 25
means "I may not bind this", not "something is listening", and reporting
the first as the second is a lie an operator would act on.
The plan is one list, and it will have three readers: --dry-run prints it,
the interface will show it before anything happens, and apply will walk it.
What you are shown is what runs.
Tested on a fresh Debian 13 in qemu, which has neither Docker nor Node and
so exercises every unavailable shape: 23 checks, including that nothing was
created by any of it. The lab that machine runs in is in e2e/vm.
jcoffey-dev