Docker Engine v20.10 and up includes optimizations to verify if images in the
local image cache need updating before pulling, preventing the Docker Engine
from making unnecessary API requests. These optimizations require the container
image registry to conform to the Open Container Initiative Distribution Specification
(https://github.com/opencontainers/distribution-spec).
While most registries conform to the specification, we encountered some registries
to be non-compliant, resulting in `docker pull` to fail.
As a temporary solution, Docker Engine v20.10 includes a fallback mechanism to
allow `docker pull` to be functional when using a non-compliant registry. A
warning message is printed in this situation:
WARNING Failed to pull manifest by the resolved digest. This registry does not
appear to conform to the distribution registry specification; falling back to
pull by tag. This fallback is DEPRECATED, and will be removed in a future
release.
The fallback is added to allow users to either migrate their images to a compliant
registry, or for these registries to become compliant.
Note that this fallback only addresses failures on `docker pull`. Other commands,
such as `docker stack deploy`, or pulling images with `containerd` will continue
to fail.
Given that other functionality is still broken with these registries, we consider
this fallback a _temporary_ solution, and will remove the fallback in an upcoming
major release.
Signed-off-by: Sebastiaan van Stijn <github@gone.nl>
Looks like the YAML conversion doesn't like lines starting with `[`, and
causing it to use the "compact" formatting in the generated YAML.
This patch un-wraps these lines to prevent this.
Signed-off-by: Sebastiaan van Stijn <github@gone.nl>
To create this, I ran every JSON document through `jq -S` (which sorts the keys and consistently pretty-prints the result in a format which matches the majority of documents in this file).
Signed-off-by: Tianon Gravi <admwiggin@gmail.com>
Docker v17.07 introduced an experimental `--stream` flag on `docker build` which
allowed the build-context to be incrementally sent to the daemon, instead of
unconditionally sending the whole build-context.
This functionality has been reimplemented as part of BuildKit, which uses streaming
by default and the `--stream` option will be ignored when using the classic builder,
printing a deprecation warning instead.
Users that want to use this feature are encouraged to enable BuildKit by setting
the `DOCKER_BUILDKIT=1` environment variable or through the daemon or CLI configuration
files.
Signed-off-by: Sebastiaan van Stijn <github@gone.nl>
The experimental feature to run Linux containers on Windows (LCOW) was introduced
as a technical preview in Docker 17.09. While many enhancements were made after
its introduction, the feature never reached completeness, and development has
now stopped in favor of running docker natively on Linux in WSL2.
Developers that need to run Linux workloads on a Windows host are encouraged
to use Docker Desktop with WSL2 instead.
Signed-off-by: Sebastiaan van Stijn <github@gone.nl>
The CLI disabled experimental features by default, requiring users
to set a configuration option to enable them.
Disabling experimental features was a request from Enterprise users
that did not want experimental features to be accessible.
We are changing this policy, and now enable experimental features
by default. Experimental features may still change and/or removed,
and will be highlighted in the documentation and "usage" output.
For example, the `docker manifest inspect --help` output now shows:
EXPERIMENTAL:
docker manifest inspect is an experimental feature.
Experimental features provide early access to product functionality. These features
may change between releases without warning or can be removed entirely from a future
release. Learn more about experimental features: https://docs.docker.com/go/experimental/
Signed-off-by: Sebastiaan van Stijn <github@gone.nl>
Some deprecations are ammended during a major (YY.MM) release, to
inform users as early as possible about deprecations. Removing the
minor version from this overview clarifies that features are
marked deprecated during which major release's lifecycle.
Signed-off-by: Sebastiaan van Stijn <github@gone.nl>
If a file contains trailing whitespace, the YAML generator uses a
compact format, which is hard to read.
Signed-off-by: Sebastiaan van Stijn <github@gone.nl>
The Dockerfile `ENV` instruction allows values to be set using either `ENV name=value`
or `ENV name value`. The latter (`ENV name value`) form can be ambiguous, for example,
the following defines a single env-variable (`ONE`) with value `"TWO= THREE=world"`,
but may have intended to be setting three env-vars:
ENV ONE TWO= THREE=world
This format also does not allow setting multiple environment-variables in a single
`ENV` line in the Dockerfile.
Use of the `ENV name value` syntax is discouraged, and may be removed in a future
release. Users are encouraged to update their Dockerfiles to use the `ENV name=value`
syntax, for example:
ENV ONE="" TWO="" THREE="world"
Signed-off-by: Sebastiaan van Stijn <github@gone.nl>
The `ENV key value` form can be ambiguous, for example, the following defines
a single env-variable (`ONE`) with value `"TWO= THREE=world"`:
ENV ONE TWO= THREE=world
While we cannot deprecate/remove that syntax (as it would break existing
Dockerfiles), we should reduce exposure of the format in our examples.
Signed-off-by: Sebastiaan van Stijn <github@gone.nl>
When creating and updating services, we need to avoid unneeded service churn.
The interaction of separate lists to "add" and "drop" capabilities, a special
("ALL") capability, as well as a "relaxed" format for accepted capabilities
(case-insensitive, `CAP_` prefix optional) make this rather involved.
This patch updates how we handle `--cap-add` / `--cap-drop` when _creating_ as
well as _updating_, with the following rules/assumptions applied:
- both existing (service spec) and new (values passed through flags or in
the compose-file) are normalized and de-duplicated before use.
- the special "ALL" capability is equivalent to "all capabilities" and taken
into account when normalizing capabilities. Combining "ALL" capabilities
and other capabilities is therefore equivalent to just specifying "ALL".
- adding capabilities takes precedence over dropping, which means that if
a capability is both set to be "dropped" and to be "added", it is removed
from the list to "drop".
- the final lists should be sorted and normalized to reduce service churn
- no validation of capabilities is handled by the client. Validation is
delegated to the daemon/server.
When deploying a service using a docker-compose file, the docker-compose file
is *mostly* handled as being "declarative". However, many of the issues outlined
above also apply to compose-files, so similar handling is applied to compose
files as well to prevent service churn.
Signed-off-by: Sebastiaan van Stijn <github@gone.nl>
The docker CLI up until v1.7.0 used the `~/.dockercfg` file to store credentials
after authenticating to a registry (`docker login`). Docker v1.7.0 replaced this
file with a new CLI configuration file, located in `~/.docker/config.json`. When
implementing the new configuration file, the old file (and file-format) was kept
as a fall-back, to assist existing users with migrating to the new file.
Given that the old file format encourages insecure storage of credentials
(credentials are stored unencrypted), and that no version of the CLI since
Docker v1.7.0 has created this file, the file is marked deprecated, and support
for this file will be removed in a future release.
Signed-off-by: Sebastiaan van Stijn <github@gone.nl>
