The daemon currently provides support for API versions all the way back
to v1.12, which is the version of the API that shipped with docker 1.0. On
Windows, the minimum supported version is v1.24.
Such old versions of the client are rare, and supporting older API versions
has accumulated significant amounts of code to remain backward-compatible
(which is largely untested, and a "best-effort" at most).
This patch updates the minimum API version to v1.24, which is the fallback
API version used when API-version negotiation fails. The intent is to start
deprecating older API versions, but no code is removed yet as part of this
patch, and a DOCKER_MIN_API_VERSION environment variable is added, which
allows overriding the minimum version (to allow restoring the behavior from
before this patch).
With this patch the daemon defaults to API v1.24 as minimum:
docker version
Client:
Version: 24.0.2
API version: 1.43
Go version: go1.20.4
Git commit: cb74dfc
Built: Thu May 25 21:50:49 2023
OS/Arch: linux/arm64
Context: default
Server:
Engine:
Version: dev
API version: 1.44 (minimum version 1.24)
Go version: go1.21.3
Git commit: 0322a29b9ef8806aaa4b45dc9d9a2ebcf0244bf4
Built: Mon Dec 4 15:22:17 2023
OS/Arch: linux/arm64
Experimental: false
containerd:
Version: v1.7.9
GitCommit: 4f03e100cb967922bec7459a78d16ccbac9bb81d
runc:
Version: 1.1.10
GitCommit: v1.1.10-0-g18a0cb0
docker-init:
Version: 0.19.0
GitCommit: de40ad0
Trying to use an older version of the API produces an error:
DOCKER_API_VERSION=1.23 docker version
Client:
Version: 24.0.2
API version: 1.23 (downgraded from 1.43)
Go version: go1.20.4
Git commit: cb74dfc
Built: Thu May 25 21:50:49 2023
OS/Arch: linux/arm64
Context: default
Error response from daemon: client version 1.23 is too old. Minimum supported API version is 1.24, please upgrade your client to a newer version
To restore the previous minimum, users can start the daemon with the
DOCKER_MIN_API_VERSION environment variable set:
DOCKER_MIN_API_VERSION=1.12 dockerd
API 1.12 is the oldest supported API version on Linux;
docker version
Client:
Version: 24.0.2
API version: 1.43
Go version: go1.20.4
Git commit: cb74dfc
Built: Thu May 25 21:50:49 2023
OS/Arch: linux/arm64
Context: default
Server:
Engine:
Version: dev
API version: 1.44 (minimum version 1.12)
Go version: go1.21.3
Git commit: 0322a29b9ef8806aaa4b45dc9d9a2ebcf0244bf4
Built: Mon Dec 4 15:22:17 2023
OS/Arch: linux/arm64
Experimental: false
containerd:
Version: v1.7.9
GitCommit: 4f03e100cb967922bec7459a78d16ccbac9bb81d
runc:
Version: 1.1.10
GitCommit: v1.1.10-0-g18a0cb0
docker-init:
Version: 0.19.0
GitCommit: de40ad0
When using the `DOCKER_MIN_API_VERSION` with a version of the API that
is not supported, an error is produced when starting the daemon;
DOCKER_MIN_API_VERSION=1.11 dockerd --validate
invalid DOCKER_MIN_API_VERSION: minimum supported API version is 1.12: 1.11
DOCKER_MIN_API_VERSION=1.45 dockerd --validate
invalid DOCKER_MIN_API_VERSION: maximum supported API version is 1.44: 1.45
Specifying a malformed API version also produces the same error;
DOCKER_MIN_API_VERSION=hello dockerd --validate
invalid DOCKER_MIN_API_VERSION: minimum supported API version is 1.12: hello
Signed-off-by: Sebastiaan van Stijn <github@gone.nl>
08e4e88482