Deprecated Docker Engine features

Table of contents

This page provides an overview of features that are deprecated in Engine. Changes in packaging, and supported (Linux) distributions are not included. To learn about end of support for Linux distributions, refer to the release notes.

Feature deprecation policy

As changes are made to Docker there may be times when existing features need to be removed or replaced with newer features. Before an existing feature is removed it is labeled as "deprecated" within the documentation and remains in Docker for at least one stable release unless specified explicitly otherwise. After that time it may be removed.

Users are expected to take note of the list of deprecated features each release and plan their migration away from those features, and (if applicable) towards the replacement features as soon as possible.

Deprecated engine features

The following table provides an overview of the current status of deprecated features:

Deprecated: the feature is marked "deprecated" and should no longer be used.

The feature may be removed, disabled, or change behavior in a future release. The "Deprecated" column contains the release in which the feature was marked deprecated, whereas the "Remove" column contains a tentative release in which the feature is to be removed. If no release is included in the "Remove" column, the release is yet to be decided on.
Removed: the feature was removed, disabled, or hidden.

Refer to the linked section for details. Some features are "soft" deprecated, which means that they remain functional for backward compatibility, and to allow users to migrate to alternatives. In such cases, a warning may be printed, and users should not rely on this feature.

Status	Feature	Deprecated	Remove
Deprecated	Non-standard fields in image inspect	v27.0	v28.0
Deprecated	API CORS headers	v27.0	v28.0
Deprecated	Graphdriver plugins (experimental)	v27.0	v28.0
Deprecated	Unauthenticated TCP connections	v26.0	v28.0
Deprecated	`Container` and `ContainerConfig` fields in Image inspect	v25.0	v26.0
Deprecated	Deprecate legacy API versions	v25.0	v26.0
Removed	Container short ID in network Aliases field	v25.0	v26.0
Deprecated	IsAutomated field, and `is-automated` filter on `docker search`	v25.0	v26.0
Removed	logentries logging driver	v24.0	v25.0
Removed	OOM-score adjust for the daemon	v24.0	v25.0
Removed	BuildKit build information	v23.0	v24.0
Deprecated	Legacy builder for Linux images	v23.0	-
Deprecated	Legacy builder fallback	v23.0	-
Removed	Btrfs storage driver on CentOS 7 and RHEL 7	v20.10	v23.0
Removed	Support for encrypted TLS private keys	v20.10	v23.0
Removed	Kubernetes stack and context support	v20.10	v23.0
Deprecated	Pulling images from non-compliant image registries	v20.10	-
Removed	Linux containers on Windows (LCOW)	v20.10	v23.0
Deprecated	BLKIO weight options with cgroups v1	v20.10	-
Removed	Kernel memory limit	v20.10	v23.0
Removed	Classic Swarm and overlay networks using external key/value stores	v20.10	v23.0
Removed	Support for the legacy `~/.dockercfg` configuration file for authentication	v20.10	v23.0
Deprecated	CLI plugins support	v20.10	-
Deprecated	Dockerfile legacy `ENV name value` syntax	v20.10	-
Removed	`docker build --stream` flag (experimental)	v20.10	v20.10
Deprecated	`fluentd-async-connect` log opt	v20.10	-
Removed	Configuration options for experimental CLI features	v19.03	v23.0
Deprecated	Pushing and pulling with image manifest v2 schema 1	v19.03	v27.0
Removed	`docker engine` subcommands	v19.03	v20.10
Removed	Top-level `docker deploy` subcommand (experimental)	v19.03	v20.10
Removed	`docker stack deploy` using "dab" files (experimental)	v19.03	v20.10
Removed	Support for the `overlay2.override_kernel_check` storage option	v19.03	v24.0
Removed	AuFS storage driver	v19.03	v24.0
Removed	Legacy "overlay" storage driver	v18.09	v24.0
Removed	Device mapper storage driver	v18.09	v25.0
Removed	Use of reserved namespaces in engine labels	v18.06	v20.10
Removed	`--disable-legacy-registry` override daemon option	v17.12	v19.03
Removed	Interacting with V1 registries	v17.06	v17.12
Removed	Asynchronous `service create` and `service update` as default	v17.05	v17.10
Removed	`-g` and `--graph` flags on `dockerd`	v17.05	v23.0
Deprecated	Top-level network properties in NetworkSettings	v1.13	v17.12
Removed	`filter` option for `/images/json` endpoint	v1.13	v20.10
Removed	`repository:shortid` image references	v1.13	v17.12
Removed	`docker daemon` subcommand	v1.13	v17.12
Removed	Duplicate keys with conflicting values in engine labels	v1.13	v17.12
Deprecated	`MAINTAINER` in Dockerfile	v1.13	-
Deprecated	API calls without a version	v1.13	v17.12
Removed	Backing filesystem without `d_type` support for overlay/overlay2	v1.13	v17.12
Removed	`--automated` and `--stars` flags on `docker search`	v1.12	v20.10
Deprecated	`-h` shorthand for `--help`	v1.12	v17.09
Removed	`-e` and `--email` flags on `docker login`	v1.11	v17.06
Deprecated	Separator (`:`) of `--security-opt` flag on `docker run`	v1.11	v17.06
Deprecated	Ambiguous event fields in API	v1.10	-
Removed	`-f` flag on `docker tag`	v1.10	v1.12
Removed	HostConfig at API container start	v1.10	v1.12
Removed	`--before` and `--since` flags on `docker ps`	v1.10	v1.12
Removed	Driver-specific log tags	v1.9	v1.12
Removed	Docker Content Trust `ENV` passphrase variables name change	v1.9	v1.12
Removed	`/containers/(id or name)/copy` endpoint	v1.8	v1.12
Removed	LXC built-in exec driver	v1.8	v1.10
Removed	Old Command Line Options	v1.8	v1.10
Removed	`--api-enable-cors` flag on `dockerd`	v1.6	v17.09
Removed	`--run` flag on `docker commit`	v0.10	v1.13
Removed	Three arguments form in `docker import`	v0.6.7	v1.12

Non-standard fields in image inspect

Deprecated in Release: v27.0 Target For Removal In Release: v28.0

The Config field returned shown in docker image inspect (and as returned by the GET /images/{name}/json API endpoint) returns additional fields that are not part of the image's configuration and not part of the Docker image specification and OCI image specification.

These fields are never set (and always return the default value for the type), but are not omitted in the response when left empty. As these fields were not intended to be part of the image configuration response, they are deprecated, and will be removed from the API in thee next release.

The following fields are currently included in the API response, but are not part of the underlying image's Config field, and deprecated:

Hostname
Domainname
AttachStdin
AttachStdout
AttachStderr
Tty
OpenStdin
StdinOnce
Image
NetworkDisabled (already omitted unless set)
MacAddress (already omitted unless set)
StopTimeout (already omitted unless set)

Graphdriver plugins (experimental)

Deprecated in Release: v27.0 Disabled by default in Release: v27.0 Target For Removal In Release: v28.0

Graphdriver plugins are an experimental feature that allow extending the Docker Engine with custom storage drivers for storing images and containers. This feature was not maintained since its inception, and will no longer be supported in upcoming releases.

Support for graphdriver plugins is disabled by default in v27.0, and will be removed v28.0. An DOCKERD_DEPRECATED_GRAPHDRIVER_PLUGINS environment variable is provided in v27.0 to re-enable the feature. This environment variable must be set to a non-empty value in the daemon's environment.

The DOCKERD_DEPRECATED_GRAPHDRIVER_PLUGINS environment variable, along with support for graphdriver plugins, will be removed in v28.0. Users of this feature are recommended to instead configure the Docker Engine to use the containerd image store and a custom snapshotter

API CORS headers

Deprecated in Release: v27.0 Target For Removal In Release: v28.0

The api-cors-header configuration option for the Docker daemon is insecure, and is therefore deprecated and scheduled for removal. Incorrectly setting this option could leave a window of opportunity for unauthenticated cross-origin requests to be accepted by the daemon.

Starting in Docker Engine v27.0, this flag can still be set, but it has no effect unless the environment variable DOCKERD_DEPRECATED_CORS_HEADER is also set to a non-empty value.

This flag will be removed altogether in v28.0.

This is a breaking change for authorization plugins and other programs that depend on this option for accessing the Docker API from a browser. If you need to access the API through a browser, use a reverse proxy.

Unauthenticated TCP connections

Deprecated in Release: v26.0 Target For Removal In Release: v28.0

Configuring the Docker daemon to listen on a TCP address will require mandatory TLS verification. This change aims to ensure secure communication by preventing unauthorized access to the Docker daemon over potentially insecure networks. This mandatory TLS requirement applies to all TCP addresses except tcp://localhost.

In version 27.0 and later, specifying --tls=false or --tlsverify=false CLI flags causes the daemon to fail to start if it's also configured to accept remote connections over TCP. This also applies to the equivalent configuration options in daemon.json.

To facilitate remote access to the Docker daemon over TCP, you'll need to implement TLS verification. This secures the connection by encrypting data in transit and providing a mechanism for mutual authentication.

For environments remote daemon access isn't required, we recommend binding the Docker daemon to a Unix socket. For daemons where remote access is required and where TLS encryption is not feasible, you may want to consider using SSH as an alternative solution.

For further information, assistance, and step-by-step instructions on configuring TLS (or SSH) for the Docker daemon, refer to Protect the Docker daemon socket.

`Container` and `ContainerConfig` fields in Image inspect

Deprecated in Release: v25.0 Target For Removal In Release: v26.0

The Container and ContainerConfig fields returned by docker inspect are mostly an implementation detail of the classic (non-BuildKit) image builder. These fields are not portable and are empty when using the BuildKit-based builder (enabled by default since v23.0). These fields are deprecated in v25.0 and will be omitted starting from v26.0. If image configuration of an image is needed, you can obtain it from the Config field.

Deprecate legacy API versions

Deprecated in Release: v25.0 Target For Removal In Release: v26.0

The Docker daemon provides a versioned API for backward compatibility with old clients. Docker clients can perform API-version negotiation to select the most recent API version supported by the daemon (downgrading to and older version of the API when necessary). API version negotiation was introduced in Docker v1.12.0 (API 1.24), and clients before that used a fixed API version.

Docker Engine versions through v25.0 provide support for all API versions included in stable releases for a given platform. For Docker daemons on Linux, the earliest supported API version is 1.12 (corresponding with Docker Engine v1.0.0), whereas for Docker daemons on Windows, the earliest supported API version is 1.24 (corresponding with Docker Engine v1.12.0).

Support for legacy API versions (providing old API versions on current versions of the Docker Engine) is primarily intended to provide compatibility with recent, but still supported versions of the client, which is a common scenario (the Docker daemon may be updated to the latest release, but not all clients may be up-to-date or vice versa). Support for API versions before that (API versions provided by EOL versions of the Docker Daemon) is provided on a "best effort" basis.

Use of old API versions is rare, and support for legacy API versions involves significant complexity (Docker 1.0.0 having been released 10 years ago). Because of this, we'll start deprecating support for legacy API versions.

Docker Engine v25.0 by default disables API version older than 1.24 (aligning the minimum supported API version between Linux and Windows daemons). When connecting with a client that uses an API version older than 1.24, the daemon returns an error. The following example configures the Docker CLI to use API version 1.23, which produces an error:

DOCKER_API_VERSION=1.23 docker version
Error response from daemon: client version 1.23 is too old. Minimum supported API version is 1.24,
upgrade your client to a newer version

An environment variable (DOCKER_MIN_API_VERSION) is introduced that allows re-enabling older API versions in the daemon. This environment variable must be set in the daemon's environment (for example, through a systemd override file), and the specified API version must be supported by the daemon (1.12 or higher on Linux, or 1.24 or higher on Windows).

Support for API versions lower than 1.24 will be permanently removed in Docker Engine v26, and the minimum supported API version will be incrementally raised in releases following that.

We do not recommend depending on the DOCKER_MIN_API_VERSION environment variable other than for exceptional cases where it's not possible to update old clients, and those clients must be supported.

Container short ID in network Aliases field

Deprecated in Release: v25.0 Removed In Release: v26.0

The Aliases field returned by docker inspect contains the container short ID once the container is started. This behavior is deprecated in v25.0 but kept until the next release, v26.0. Starting with that version, the Aliases field will only contain the aliases set through the docker container create and docker run flag --network-alias.

A new field DNSNames containing the container name (if one was specified), the hostname, the network aliases, as well as the container short ID, has been introduced in v25.0 and should be used instead of the Aliases field.

IsAutomated field, and `is-automated` filter on `docker search`

Deprecated in Release: v25.0 Target For Removal In Release: v26.0

The is_automated field has been deprecated by Docker Hub's search API. Consequently, the IsAutomated field in image search will always be set to false in future, and searching for "is-automated=true" will yield no results.

The AUTOMATED column has been removed from the default docker search and docker image search output in v25.0, and the corresponding IsAutomated templating option will be removed in v26.0.

Logentries logging driver

Deprecated in Release: v24.0 Removed in Release: v25.0

The logentries service SaaS was shut down on November 15, 2022, rendering this logging driver non-functional. Users should no longer use this logging driver, and the driver has been removed in Docker 25.0. Existing containers using this logging-driver are migrated to use the "local" logging driver after upgrading.

OOM-score adjust for the daemon

Deprecated in Release: v24.0 Removed in Release: v25.0

The oom-score-adjust option was added to prevent the daemon from being OOM-killed before other processes. This option was mostly added as a convenience, as running the daemon as a systemd unit was not yet common.

Having the daemon set its own limits is not best-practice, and something better handled by the process-manager starting the daemon.

Docker v20.10 and newer no longer adjust the daemon's OOM score by default, instead setting the OOM-score to the systemd unit (OOMScoreAdjust) that's shipped with the packages.

Users currently depending on this feature are recommended to adjust the daemon's OOM score using systemd or through other means, when starting the daemon.

BuildKit build information

Deprecated in Release: v23.0 Removed in Release: v24.0

Build information structures have been introduced in BuildKit v0.10.0 and are generated with build metadata that allows you to see all the sources (images, Git repositories) that were used by the build with their exact versions and also the configuration that was passed to the build. This information is also embedded into the image configuration if one is generated.

Legacy builder for Linux images

Deprecated in Release: v23.0

Docker v23.0 now uses BuildKit by default to build Linux images, and uses the Buildx CLI component for docker build. With this change, docker build now exposes all advanced features that BuildKit provides and which were previously only available through the docker buildx subcommands.

The Buildx component is installed automatically when installing the docker CLI using our .deb or .rpm packages, and statically linked binaries are provided both on download.docker.com, and through the docker/buildx-bin image on Docker Hub. Refer the Buildx section for detailed instructions on installing the Buildx component.

This release marks the beginning of the deprecation cycle of the classic ("legacy") builder for Linux images. No active development will happen on the classic builder (except for bugfixes). BuildKit development started five Years ago, left the "experimental" phase since Docker 18.09, and is already the default builder for Docker Desktop. While we're comfortable that BuildKit is stable for general use, there may be some changes in behavior. If you encounter issues with BuildKit, we encourage you to report issues in the BuildKit issue tracker on GitHub{:target="blank" rel="noopener" class=""}

Classic builder for building Windows images

BuildKit does not (yet) provide support for building Windows images, and docker build continues to use the classic builder to build native Windows images on Windows daemons.

Legacy builder fallback

Deprecated in Release: v23.0

Docker v23.0 now uses BuildKit by default to build Linux images, which requires the Buildx component to build images with BuildKit. There may be situations where the Buildx component is not available, and BuildKit cannot be used.

To provide a smooth transition to BuildKit as the default builder, Docker v23.0 has an automatic fallback for some situations, or produces an error to assist users to resolve the problem.

In situations where the user did not explicitly opt-in to use BuildKit (i.e., DOCKER_BUILDKIT=1 is not set), the CLI automatically falls back to the classic builder, but prints a deprecation warning:

DEPRECATED: The legacy builder is deprecated and will be removed in a future release.
            Install the buildx component to build images with BuildKit:
            https://docs.docker.com/go/buildx/

This situation may occur if the docker CLI is installed using the static binaries, and the Buildx component is not installed or not installed correctly. This fallback will be removed in a future release, therefore we recommend to install the Buildx component and use BuildKit for your builds, or opt-out of using BuildKit with DOCKER_BUILDKIT=0.

If you opted-in to use BuildKit (DOCKER_BUILDKIT=1), but the Buildx component is missing, an error is printed instead, and the docker build command fails:

ERROR: BuildKit is enabled but the buildx component is missing or broken.
       Install the buildx component to build images with BuildKit:
       https://docs.docker.com/go/buildx/

We recommend to install the Buildx component to continue using BuildKit for your builds, but alternatively, users can either unset the DOCKER_BUILDKIT environment variable to fall back to the legacy builder, or opt-out of using BuildKit with DOCKER_BUILDKIT=0.

Be aware that the classic builder is deprecated so both the automatic fallback and opting-out of using BuildKit will no longer be possible in a future release.

Btrfs storage driver on CentOS 7 and RHEL 7

Removed in Release: v23.0

The btrfs storage driver on CentOS and RHEL was provided as a technology preview by CentOS and RHEL, but has been deprecated since the Red Hat Enterprise Linux 7.4 release, and removed in CentOS 8 and RHEL 8. Users of the btrfs storage driver on CentOS are recommended to migrate to a different storage driver, such as overlay2, which is now the default storage driver. Docker 23.0 continues to provide the btrfs storage driver to allow users to migrate to an alternative driver. The next release of Docker will no longer provide this driver.

Support for encrypted TLS private keys

Deprecated in Release: v20.10

Removed in Release: v23.0

Use of encrypted TLS private keys has been deprecated, and has been removed. Golang has deprecated support for legacy PEM encryption (as specified in RFC 1423), as it is insecure by design (see https://go-review.googlesource.com/c/go/+/264159).

This feature allowed using an encrypted private key with a supplied password, but did not provide additional security as the encryption is known to be broken, and the key is sitting next to the password in the filesystem. Users are recommended to decrypt the private key, and store it un-encrypted to continue using it.

Kubernetes stack and context support

Deprecated in Release: v20.10 Removed in Release: v23.0

Following the deprecation of Compose on Kubernetes, support for Kubernetes in the stack and context commands has been removed from the CLI, and options related to this functionality are now either ignored, or may produce an error.

The following command-line flags are removed from the docker context subcommands:

--default-stack-orchestrator - swarm is now the only (and default) orchestrator for stacks.
--kubernetes - the Kubernetes endpoint can no longer be stored in docker context.
--kubeconfig - exporting a context as a kubeconfig file is no longer supported.

The output produced by the docker context inspect subcommand no longer contains information about StackOrchestrator and Kubernetes endpoints for new contexts.

The following command-line flags are removed from the docker stack subcommands:

--kubeconfig - using a kubeconfig file as context is no longer supported.
--namespace - configuring the Kubernetes namespace for stacks is no longer supported.
--orchestrator - swarm is now the only (and default) orchestrator for stacks.

The DOCKER_STACK_ORCHESTRATOR, DOCKER_ORCHESTRATOR, and KUBECONFIG environment variables, as well as the stackOrchestrator option in the ~/.docker/config.json CLI configuration file are no longer used, and ignored.

Pulling images from non-compliant image registries

Deprecated in Release: v20.10

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.

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.

Linux containers on Windows (LCOW) (experimental)

Deprecated in Release: v20.10 Removed in Release: v23.0

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 who want to run Linux workloads on a Windows host are encouraged to use Docker Desktop with WSL2 instead.

BLKIO weight options with cgroups v1

Deprecated in Release: v20.10

Specifying blkio weight (docker run --blkio-weight and docker run --blkio-weight-device) is now marked as deprecated when using cgroups v1 because the corresponding features were removed in Linux kernel v5.0 and up. When using cgroups v2, the --blkio-weight options are implemented using `io.weight.

Kernel memory limit

Deprecated in Release: v20.10 Removed in Release: v23.0

Specifying kernel memory limit (docker run --kernel-memory) is no longer supported because the Linux kernel deprecated kmem.limit_in_bytes in v5.4. The OCI runtime specification now marks this option (as well as --kernel-memory-tcp) as "NOT RECOMMENDED", and OCI runtimes such as runc no longer support this option.

Docker API v1.42 and up now ignores this option when set. Older versions of the API continue to accept the option, but depending on the OCI runtime used, may take no effect.

Note

While not deprecated (yet) in Docker, the OCI runtime specification also deprecated the memory.kmem.tcp.limit_in_bytes option. When using runc as runtime, this option takes no effect. The Linux kernel did not explicitly deprecate this feature, and there is a tracking ticket in the runc issue tracker to determine if this option should be reinstated or if this was an oversight of the Linux kernel maintainers (see opencontainers/runc#3174).

The memory.kmem.tcp.limit_in_bytes option is only supported with cgroups v1, and not available on installations running with cgroups v2. This option is only supported by the API, and not exposed on the docker command-line.

Classic Swarm and overlay networks using cluster store

Deprecated in Release: v20.10 Removed in Release: v23.0

Standalone ("classic") Swarm has been deprecated, and with that the use of overlay networks using an external key/value store. The corresponding--cluster-advertise, --cluster-store, and --cluster-store-opt daemon options have been removed.

Support for legacy `~/.dockercfg` configuration files

Deprecated in Release: v20.10 Removed in Release: v23.0

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, support for this file, and its format has been removed.

Configuration options for experimental CLI features

Deprecated in Release: v19.03

Removed in Release: v23.0

The DOCKER_CLI_EXPERIMENTAL environment variable and the corresponding experimental field in the CLI configuration file are deprecated. Experimental features are enabled by default, and these configuration options are no longer functional.

Starting with v23.0, the Docker CLI no longer prints Experimental for the client in the output of docker version, and the field has been removed from the JSON format.

CLI plugins support

Deprecated in Release: v20.10

CLI Plugin API is now marked as deprecated.

Dockerfile legacy `ENV name value` syntax

Deprecated in Release: v20.10

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"

`docker build --stream` flag (experimental)

Deprecated in Release: v20.10 Removed in Release: v20.10

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.

`fluentd-async-connect` log opt

Deprecated in Release: v20.10

The --log-opt fluentd-async-connect option for the fluentd logging driver is deprecated in favor of --log-opt fluentd-async. A deprecation message is logged in the daemon logs if the old option is used:

fluent#New: AsyncConnect is now deprecated, use Async instead

Users are encouraged to use the fluentd-async option going forward, as support for the old option will be removed in a future release.

Pushing and pulling with image manifest v2 schema 1

Deprecated in Release: v19.03

Disabled by default in Release: v26.0

Target For Removal In Release: v27.0

The image manifest v2 schema 1 and "Docker Image v1" formats were deprecated in favor of the v2 schema 2 and OCI image spec formats.

These legacy formats should no longer be used, and users are recommended to update images to use current formats, or to upgrade to more current images. Starting with Docker v26.0, pulling these images is disabled by default, and produces an error when attempting to pull the image:

$ docker pull ubuntu:10.04
Error response from daemon:
[DEPRECATION NOTICE] Docker Image Format v1 and Docker Image manifest version 2, schema 1 support is disabled by default and will be removed in an upcoming release.
Suggest the author of docker.io/library/ubuntu:10.04 to upgrade the image to the OCI Format or Docker Image manifest v2, schema 2.
More information at https://docs.docker.com/go/deprecated-image-specs/

An environment variable (DOCKER_ENABLE_DEPRECATED_PULL_SCHEMA_1_IMAGE) is added in Docker v26.0 that allows re-enabling support for these image formats in the daemon. This environment variable must be set to a non-empty value in the daemon's environment (for example, through a systemd override file). Support for the DOCKER_ENABLE_DEPRECATED_PULL_SCHEMA_1_IMAGE environment variable will be removed in Docker v27.0 after which this functionality is removed permanently.

`docker engine` subcommands

Deprecated in Release: v19.03

Removed in Release: v20.10

The docker engine activate, docker engine check, and docker engine update provided an alternative installation method to upgrade Docker Community engines to Docker Enterprise, using an image-based distribution of the Docker Engine.

This feature was only available on Linux, and only when executed on a local node. Given the limitations of this feature, and the feature not getting widely adopted, the docker engine subcommands will be removed, in favor of installation through standard package managers.

Top-level `docker deploy` subcommand (experimental)

Deprecated in Release: v19.03

Removed in Release: v20.10

The top-level docker deploy command (using the "Docker Application Bundle" (.dab) file format was introduced as an experimental feature in Docker 1.13 / 17.03, but superseded by support for Docker Compose files using the docker stack deploy subcommand.

`docker stack deploy` using "dab" files (experimental)

Deprecated in Release: v19.03

Removed in Release: v20.10

With no development being done on this feature, and no active use of the file format, support for the DAB file format and the top-level docker deploy command (hidden by default in 19.03), will be removed, in favour of docker stack deploy using compose files.

Support for the `overlay2.override_kernel_check` storage option

Deprecated in Release: v19.03 Removed in Release: v24.0

This daemon configuration option disabled the Linux kernel version check used to detect if the kernel supported OverlayFS with multiple lower dirs, which is required for the overlay2 storage driver. Starting with Docker v19.03.7, the detection was improved to no longer depend on the kernel version, so this option was no longer used.

AuFS storage driver

Deprecated in Release: v19.03 Removed in Release: v24.0

The aufs storage driver is deprecated in favor of overlay2, and has been removed in a Docker Engine v24.0. Users of the aufs storage driver must migrate to a different storage driver, such as overlay2, before upgrading to Docker Engine v24.0.

The aufs storage driver facilitated running Docker on distros that have no support for OverlayFS, such as Ubuntu 14.04 LTS, which originally shipped with a 3.14 kernel.

Now that Ubuntu 14.04 is no longer a supported distro for Docker, and overlay2 is available to all supported distros (as they are either on kernel 4.x, or have support for multiple lowerdirs backported), there is no reason to continue maintenance of the aufs storage driver.

Legacy overlay storage driver

Deprecated in Release: v18.09 Removed in Release: v24.0

The overlay storage driver is deprecated in favor of the overlay2 storage driver, which has all the benefits of overlay, without its limitations (excessive inode consumption). The legacy overlay storage driver has been removed in Docker Engine v24.0. Users of the overlay storage driver should migrate to the overlay2 storage driver before upgrading to Docker Engine v24.0.

The legacy overlay storage driver allowed using overlayFS-backed filesystems on kernels older than v4.x. Now that all supported distributions are able to run overlay2 (as they are either on kernel 4.x, or have support for multiple lowerdirs backported), there is no reason to keep maintaining the overlay storage driver.

Device mapper storage driver

Deprecated in Release: v18.09 Disabled by default in Release: v23.0 Removed in Release: v25.0

The devicemapper storage driver is deprecated in favor of overlay2, and has been removed in Docker Engine v25.0. Users of the devicemapper storage driver must migrate to a different storage driver, such as overlay2, before upgrading to Docker Engine v25.0.

The devicemapper storage driver facilitates running Docker on older (3.x) kernels that have no support for other storage drivers (such as overlay2, or btrfs).

Now that support for overlay2 is added to all supported distros (as they are either on kernel 4.x, or have support for multiple lowerdirs backported), there is no reason to continue maintenance of the devicemapper storage driver.

Use of reserved namespaces in engine labels

Deprecated in Release: v18.06

Removed In Release: v20.10

The namespaces com.docker.*, io.docker.*, and org.dockerproject.* in engine labels were always documented to be reserved, but there was never any enforcement.

Usage of these namespaces will now cause a warning in the engine logs to discourage their use, and will error instead in v20.10 and above.

`--disable-legacy-registry` override daemon option

Disabled In Release: v17.12

Removed In Release: v19.03

The --disable-legacy-registry flag was disabled in Docker 17.12 and will print an error when used. For this error to be printed, the flag itself is still present, but hidden. The flag has been removed in Docker 19.03.

Interacting with V1 registries

Disabled By Default In Release: v17.06

Removed In Release: v17.12

Version 1.8.3 added a flag (--disable-legacy-registry=false) which prevents the Docker daemon from pull, push, and login operations against v1 registries. Though enabled by default, this signals the intent to deprecate the v1 protocol.

Support for the v1 protocol to the public registry was removed in 1.13. Any mirror configurations using v1 should be updated to use a v2 registry mirror.

Starting with Docker 17.12, support for V1 registries has been removed, and the --disable-legacy-registry flag can no longer be used, and dockerd will fail to start when set.

Asynchronous `service create` and `service update` as default

Deprecated In Release: v17.05

Disabled by default in release: v17.10

Docker 17.05 added an optional --detach=false option to make the docker service create and docker service update work synchronously. This option will be enabled by default in Docker 17.10, at which point the --detach flag can be used to use the previous (asynchronous) behavior.

The default for this option will also be changed accordingly for docker service rollback and docker service scale in Docker 17.10.

`-g` and `--graph` flags on `dockerd`

Deprecated In Release: v17.05

Removed In Release: v23.0

The -g or --graph flag for the dockerd or docker daemon command was used to indicate the directory in which to store persistent data and resource configuration and has been replaced with the more descriptive --data-root flag. These flags were deprecated and hidden in v17.05, and removed in v23.0.