Commit 6fef143dbc switched the CLI to use
BuildKit by default, but as part of that removed the use of the
BuildkitVersion field as returned by Ping.
Some follow-up changes in commits e38e6c51ff and
e7a8748b93 updated the logic for detecting whether
BuildKit should be used or the legacy builder, but hard-coded using the
legacy builder for Windows daemons.
While Windows / WCOW does not yet support BuildKit by default, there is
work in progress to implement it, so we should not hard-code the assumption
that a Windows daemon cannot support BuildKit.
On the daemon-side, [moby@7b153b9] (Docker v23.0) changed the default as
advertised by the daemon to be BuildKit for Linux daemons. That change
still hardcoded BuildKit to be unsupported for Windows daemons (and does
not yet allow overriding the config), but this may change for future
versions of the daemon, or test-builds.
This patch:
- Re-introduces checks for the BuildkitVersion field in the "Ping" response.
- If the Ping response from the daemon advertises that it supports BuildKit,
the CLI will now use BuildKit as builder.
- If we didn't get a Ping response, or the Ping response did NOT advertise
that the daemon supported BuildKit, we continue to use the current
defaults (BuildKit for Linux daemons, and the legacy builder for Windows)
- Handling of the DOCKER_BUILDKIT environment variable is unchanged; for
CLI.BuildKitEnabled, DOCKER_BUILDKIT always takes precedence, and for
processBuilder the value is taken into account, but will print a warning
when BuildKit is disabled and a Linux daemon is used. For Windows daemons,
no warning is printed.
[moby@7b153b9]: 7b153b9e28
Signed-off-by: Sebastiaan van Stijn <github@gone.nl>
e5d26a8d40