Docker executor | GitLab

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Docker executor

GitLab Runner uses the Docker executor to run jobs on Docker images.

You can use the Docker executor to:

  • Maintain the same build environment for each job.
  • Use the same image to test commands locally without the requirement of running a job in the CI server.

The Docker executor uses Docker Engine
to run each job in a separate and isolated container. To connect to Docker Engine, the executor uses:

  • The image and services you define in .gitlab-ci.yml.
  • The configurations you define in config.toml.

Docker executor workflow

The Docker executor uses a special Docker image based on Alpine Linux that
contains the tools to run the prepare, pre-job, and post-job steps. To view the definition of
the special Docker image, see the GitLab Runner repository.

The Docker executor divides the job into several steps:

  1. Prepare: Creates and starts the services.
  2. Pre-job: Clones, restores cache,
    and downloads artifacts from previous
    stages. Runs on a special Docker image.
  3. Job: Runs your build in the Docker image you configure for the runner.
  4. Post-job: Create cache, upload artifacts to GitLab. Runs on
    a special Docker Image.

Supported configurations

The Docker executor supports the following configurations.

For known issues and additional requirements of Windows configurations, see Use Windows containers.

Runner is installed on:Executor is:Container is running:

Windowsdocker-windowsWindows
WindowsdockerLinux
LinuxdockerLinux

These configurations are not supported:

Runner is installed on:Executor is:Container is running:

Linuxdocker-windowsLinux
LinuxdockerWindows
Linuxdocker-windowsWindows
WindowsdockerWindows
Windowsdocker-windowsLinux

Use the Docker executor

To use the Docker executor, define Docker as the executor in config.toml.

The following sample shows Docker defined as the executor and example
configurations. For more information about these values, see Advanced configuration

concurrent

=

4

[[runners]]

name

=

"myRunner"

url

=

"https://gitlab.com/ci"

token

=

"......"

executor

=

"docker"

[runners.docker]

tls_verify

=

true

image

=

"my.registry.tld:5000/alpine:latest"

privileged

=

false

disable_entrypoint_overwrite

=

false

oom_kill_disable

=

false

disable_cache

=

false

volumes

=

[

"/cache"

,

]

shm_size

=

0

allowed_pull_policies

=

[

"always"

,

"if-not-present"

]

allowed_images

=

[

"my.registry.tld:5000/*:*"

]

allowed_services

=

[

"my.registry.tld:5000/*:*"

]

[runners.docker.volume_driver_ops]

"size"

=

"50G"

Configure images and services

Prerequisites:

  • The image where your job runs must have a working shell in its operating system PATH. Supported shells are:
    • For Linux:
      • sh
      • bash
      • PowerShell Core (pwsh). Introduced in 13.9.
    • For Windows:
      • PowerShell (powershell)
      • PowerShell Core (pwsh). Introduced in 13.6.

To configure the Docker executor, you define the Docker images and services in .gitlab-ci.yml and config.toml.

Use the following keywords:

  • image: The name of the Docker image that the runner uses to run jobs.

    • Enter an image from the local Docker Engine, or any image in
      Docker Hub. For more information, see the Docker documentation.
    • To define the image version, use a colon (:) to add a tag. If you don’t specify a tag,
      Docker uses latest as the version.
  • services: The additional image that creates another container and links to the image. For more information about types of services, see Services.

Define images and services in .gitlab-ci.yml

Define an image that the runner uses for all jobs and a list of
services to use during build time.

Example:

image

:

ruby:2.7

services

:

-

postgres:9.3

before_script

:

-

bundle install

test

:

script

:

-

bundle exec rake spec

To define different images and services per job:

before_script

:

-

bundle install

test:2.6

:

image

:

ruby:2.6

services

:

-

postgres:9.3

script

:

-

bundle exec rake spec

test:2.7

:

image

:

ruby:2.7

services

:

-

postgres:9.4

script

:

-

bundle exec rake spec

If you don’t define an image in .gitlab-ci.yml, the runner uses the image defined in config.toml.

Define images and services in config.toml

To add images and services to all jobs run by a runner, update [runners.docker] in the config.toml.
If you don’t define an image in .gitlab-ci.yml, the runner uses the image defined in config.toml.

Example:

[runners.docker]

image

=

"ruby:2.7"

[[runners.docker.services]]

name

=

"mysql:latest"

alias

=

"db"

[[runners.docker.services]]

name

=

"redis:latest"

alias

=

"cache"

This example uses the array of tables syntax.

Define an image from a private registry

Prerequisites:

  • To access images from a private registry, you must authenticate GitLab Runner.

To define an image from a private registry, provide the registry name and the image in .gitlab-ci.yml.

Example:

image

:

my.registry.tld:5000/namepace/image:tag

In this example, GitLab Runner searches the registry my.registry.tld:5000 for the
image namespace/image:tag.

Network configurations

You must configure a network to connect services to a CI/CD job.

To configure a network, you can either:

  • Recommended. Configure the runner to create a network for each job.
  • Define container links. Container links are a legacy feature of Docker.

Create a network for each job

You can configure the runner to create a network for each job.

When you enable this networking mode, the runner creates and uses a
user-defined Docker bridge network for each job. Docker environment
variables are not shared across the containers. For more information
about user-defined bridge networks, see the Docker documentation.

To use this networking mode, enable FF_NETWORK_PER_BUILD in either
the feature flag or the environment variable in theconfig.toml.

Do not set the network_mode.

Example:

[[runners]]

(...)

executor

=

"docker"

environment

=

["FF_NETWORK_PER_BUILD

=

1

"]

Or:

[[runners]]

(...)

executor

=

"docker"

[runners.feature_flags]

FF_NETWORK_PER_BUILD

=

true

To set the default Docker address pool, use default-address-pool in
dockerd. If CIDR ranges
are already used in the network, Docker networks may conflict with other networks on the host,
including other Docker networks.

This feature works only when the Docker daemon is configured with IPv6 enabled.
To enable IPv6 support, set enable_ipv6 to true in the Docker configuration.
For more information, see the Docker documentation.

The runner uses the build alias to resolve the job container.

How the runner creates a network for each job

When a job starts, the runner:

  1. Creates a bridge network, similar to the Docker command docker network create <network>.
  2. Connects the service and containers to the bridge network.
  3. Removes the network at the end of the job.

The container running the job and the containers running the service
resolve each other’s hostnames and aliases. This functionality is
provided by Docker.

You can configure a network mode that uses Docker legacy container links and the default Docker bridge to link the job container with the services. This network mode is the default
if FF_NETWORK_PER_BUILD is not enabled.

To configure the network, specify the networking mode in the config.toml file:

  • bridge: Use the bridge network. Default.
  • host: Use the host’s network stack inside the container.
  • none: No networking. Not recommended.

Example:

[[runners]]

(...)

executor

=

"docker"

[runners.docker]

network_mode

=

"bridge"

If you use any other network_mode value, these are taken as the name of an already existing
Docker network, which the build container connects to.

During name resolution, Docker updates the /etc/hosts file in the
container with the service container hostname and alias. However,
the service container is not able to resolve the container
name. To resolve the container name, you must create a network for each job.

Linked containers share their environment variables.

Restrict Docker images and services

To restrict Docker images and services, specify a wildcard pattern in the allowed_images and allowed_services parameters.

For example, to allow images from your private Docker registry only:

[[runners]]

(...)

executor

=

"docker"

[runners.docker]

(...)

allowed_images

=

[

"my.registry.tld:5000/*:*"

]

allowed_services

=

[

"my.registry.tld:5000/*:*"

]

To restrict to a list of images from your private Docker registry:

[[runners]]

(...)

executor

=

"docker"

[runners.docker]

(...)

allowed_images

=

[

"my.registry.tld:5000/ruby:*"

,

"my.registry.tld:5000/node:*"

]

allowed_services

=

[

"postgres:9.4"

,

"postgres:latest"

]

Access services hostnames

To access a service hostname, add the service to services in .gitlab-ci.yml.

For example, to use a WordPress instance to test an API integration with your application,
use tutum/wordpress as the service image:

services

:

-

tutum/wordpress:latest

When the job runs, the tutum/wordpress service starts. You can
access it from your build container under the hostname tutum__wordpress
and tutum-wordpress.

In addition to the specified service aliases, the runner assigns the name of the service image as an alias to the service container. You can use any of these aliases.

The runner uses the following rules to create the alias based on the image name:

  • Everything after : is stripped.
  • For the first alias, the slash (/) is replaced with double underscores (__).
  • For the second alias, the slash (/) is replaced with a single dash (-).

If you use a private service image, the runner strips any specified port and applies the rules.
The service registry.gitlab-wp.com:4999/tutum/wordpress results in the hostname
registry.gitlab-wp.com__tutum__wordpress and registry.gitlab-wp.com-tutum-wordpress.

Configuring services

To change database names or set account names, you can define environment variables
for the service.

When the runner passes variables:

  • Variables are passed to all containers. The runner cannot pass variables to specific
    containers.
  • Secure variables are passed to the build container.

For more information about configuration variables, see the documentation of each image
provided in their corresponding Docker Hub page.

Mount a directory in RAM

You can use the tmpfs option to mount a directory in RAM. This speeds up the time
required to test if there is a lot of I/O related work, such as with databases.

If you use the tmpfs and services_tmpfs options in the runner configuration,
you can specify multiple paths, each with its own options. For more information, see the
Docker documentation.

For example, to mount the data directory for the official MySQL container in RAM,
configure the config.toml:

[runners.docker]

# For the main container

[runners.docker.tmpfs]

"/var/lib/mysql"

=

"rw,noexec"

# For services

[runners.docker.services_tmpfs]

"/var/lib/mysql"

=

"rw,noexec"

Building a directory in a service

GitLab Runner mounts a /builds directory to all shared services.

For more information about using different services see:

How GitLab Runner performs the services health check

After the service starts, GitLab Runner waits for the service to
respond. The Docker executor tries to open a TCP connection to
the first exposed service in the service container.

To see how this is implemented, use the health check Go command.

Specify Docker driver operations

Specify arguments to supply to the Docker volume driver when you create volumes for builds.
For example, you can use these arguments to limit the space for each build to run, in addition to all other driver specific options.
The following example shows a config.toml where the limit that each build can consume is set to 50GB.

[runners.docker]

[runners.docker.volume_driver_ops]

"size"

=

"50G"

Configure directories for the container build and cache

To define where data is stored in the container, configure /builds and /cache
directories in the [[runners]] section in config.toml.

If you modify the /cache storage path, to mark the path as persistent you must define it in volumes = ["/my/cache/"], under the
[runners.docker] section in config.toml.

By default, the Docker executor stores builds and caches in the following directories:

  • Builds in /builds/<namespace>/<project-name>
  • Caches in /cache inside the container.

Clear the Docker cache

Introduced in GitLab Runner 13.9, all created runner resources cleaned up.

Use clear-docker-cache to remove unused containers and volumes created by the runner.

For a list of options, run the script with the help option:

clear-docker-cache 

help

The default option is prune-volumes, which removes all unused containers (dangling and unreferenced)
and volumes.

To manage cache storage efficiently, you should:

  • Run clear-docker-cache with cron regularly (for example, once a week).
  • Maintain some recent containers in the cache for performance while you
    reclaim disk space.

Clear Docker build images

The clear-docker-cache script does not remove Docker images because they are not tagged by the GitLab Runner.

To clear Docker build images:

  1. Confirm what disk space can be reclaimed:

     clear-docker-cache space
    
     Show docker disk usage
     

    ----------------------

    TYPE TOTAL ACTIVE SIZE RECLAIMABLE Images 14 9 1.306GB 545.8MB

    (

    41%

    )

    Containers 19 18 115kB 0B

    (

    0%

    )

    Local Volumes 0 0 0B 0B Build Cache 0 0 0B 0B
  2. To remove all unused containers, networks, images (dangling and unreferenced), and untagged volumes, run docker system prune.

Persistent storage

The Docker executor provides persistent storage when it runs containers.
All directories defined in volumes = are persistent between builds.

The volumes directive supports the following types of storage:

  • For dynamic storage, use <path>. The <path> is persistent between subsequent runs of the same concurrent job for that project. The data is attached to a custom cache volume: runner-<short-token>-project-<id>-concurrent-<concurrency-id>-cache-<md5-of-path>.
  • For host-bound storage, use <host-path>:<path>[:<mode>]. The <path> is bound to <host-path> on the host system. The optional <mode> specifies that this storage is read-only or read-write (default).

Persistent storage for builds

If you make the /builds directory a host-bound storage, your builds are stored in:
/builds/<short-token>/<concurrent-id>/<namespace>/<project-name>, where:

  • <short-token> is a shortened version of the Runner’s token (first 8 letters).
  • <concurrent-id> is a unique number that identifies the local job ID of the
    particular runner in context of the project.

IPC mode

The Docker executor supports sharing the IPC namespace of containers with other
locations. This maps to the docker run --ipc flag.
More details on IPC settings in Docker documentation

Privileged mode

The Docker executor supports a number of options that allows fine-tuning of the
build container. One of these options is the privileged mode.

Use Docker-in-Docker with privileged mode

The configured privileged flag is passed to the build container and all
services, thus allowing to easily use the Docker-in-Docker approach.

First, configure your runner (config.toml) to run in privileged mode:

[[runners]]

executor

=

"docker"

[runners.docker]

privileged

=

true

Then, make your build script (.gitlab-ci.yml) to use Docker-in-Docker
container:

image

:

docker:git

services

:

-

docker:dind

build

:

script

:

-

docker build -t my-image .

-

docker push my-image

Configure a Docker ENTRYPOINT

By default the Docker executor doesn’t override the ENTRYPOINT of a Docker image and passes sh or bash as COMMAND to start a container that runs the job script.

To ensure a job can run, its Docker image must:

  • Provide sh or bash
  • Define an ENTRYPOINT that starts a shell when passed sh/bash as argument

The Docker Executor runs the job’s container with an equivalent of the following command:

docker run <image> sh 

-c

"echo 'It works!'"

# or bash

If your Docker image doesn’t support this mechanism, you can override the image’s ENTRYPOINT in the project configuration as follows:

# Equivalent of

# docker run --entrypoint "" <image> sh -c "echo 'It works!'"

image

:

name

:

my-image

entrypoint

:

[

"

"

]

For more information, see Override the Entrypoint of an image and How CMD and ENTRYPOINT interact in Docker.

Job script as ENTRYPOINT

You can use ENTRYPOINT to create a Docker image that
runs the build script in a custom environment, or in secure mode.

For example, you can create a Docker image that uses an ENTRYPOINT that doesn’t
execute the build script. Instead, the Docker image executes a predefined set of commands
to build the Docker image from your directory. You run
the build container in privileged mode, and secure
the build environment of the runner.

  1. Create a new Dockerfile:

    FROM

    docker:dind

    ADD

    / /entrypoint.sh

    ENTRYPOINT

    ["/bin/sh", "/entrypoint.sh"]

  2. Create a bash script (entrypoint.sh) that is used as the ENTRYPOINT:

    #!/bin/sh

    dind docker daemon

    --host

    =

    unix:///var/run/docker.sock

    \

    --host

    =

    tcp://0.0.0.0:2375

    \

    --storage-driver

    =

    vf & docker build

    -t

    "

    $BUILD_IMAGE

    "

    .

    docker push

    "

    $BUILD_IMAGE

    "

  3. Push the image to the Docker registry.

  4. Run Docker executor in privileged mode. In config.toml define:

    [[runners]]

    executor

    =

    "docker"

    [runners.docker]

    privileged

    =

    true

  5. In your project use the following .gitlab-ci.yml:

    variables

    :

    BUILD_IMAGE

    :

    my.image

    build

    :

    image

    :

    my/docker-build:image

    script

    :

    -

    Dummy Script

Use Podman to run Docker commands

Introduced in GitLab 15.3.

If you have GitLab Runner installed on Linux, your jobs can use Podman to replace Docker as
the container runtime in the Docker executor.

Prerequisites:

  • Podman v4.2.0 or later.
  • To run services with Podman as an executor, enable the
    FF_NETWORK_PER_BUILD feature flag.
    Docker container links are legacy
    and are not supported by Podman. For services that
    create a network alias, you must install the podman-plugins package.
  1. On your Linux host, install GitLab Runner. If you installed GitLab Runner
    by using your system’s package manager, it automatically creates a gitlab-runner user.
  2. Sign in as the user that will run GitLab Runner. You must do so in a way that
    doesn’t go around pam_systemd.
    You can use SSH with the correct user. This ensures you can run systemctl as this user.
  3. Make sure that your system fulfills the prerequisites for
    a rootless Podman setup.
    Specifically, make sure your user has
    correct entries in /etc/subuid and /etc/subgid.
  4. On the Linux host, install Podman.
  5. Enable and start the Podman socket:

    systemctl 

    --user

    --now

    enable

    podman.socket
  6. Verify the Podman socket is listening:

    systemctl status 

    --user

    podman.socket
  7. Copy the socket string in the Listen key through which Podman’s API is being accessed.
  8. Make sure the Podman socket remains available after the GitLab Runner user is logged out:

    sudo

    loginctl enable-linger gitlab-runner
  9. Edit the GitLab Runner config.toml file and add the socket value to the host entry in the [[runners.docker]] section.
    For example:

    [[runners]]

    name

    =

    "podman-test-runner-2022-06-07"

    url

    =

    "https://gitlab.com"

    token

    =

    "x-XxXXXXX-xxXxXxxxxx"

    executor

    =

    "docker"

    [runners.docker]

    host

    =

    "unix:///run/user/1012/podman/podman.sock"

    tls_verify

    =

    false

    image

    =

    "quay.io/podman/stable"

    privileged

    =

    true

Use Podman to build container images from a Dockerfile

The following example uses Podman to build a container image and push the image to the GitLab Container registry.

The default container image in the Runner config.toml is set to quay.io/podman/stable, so that the CI job uses that image to execute the included commands.

variables

:

IMAGE_TAG

:

$CI_REGISTRY_IMAGE:$CI_COMMIT_REF_SLUG

before_script

:

-

podman login -u "$CI_REGISTRY_USER" -p "$CI_REGISTRY_PASSWORD" $CI_REGISTRY

oci-container-build

:

stage

:

build

script

:

-

podman build -t $IMAGE_TAG .

-

podman push $IMAGE_TAG

when

:

manual

Use Buildah to build container images from a Dockerfile

The following example shows how to use Buildah to build a container image and push the image to the GitLab Container registry.

image

:

quay.io/buildah/stable

variables

:

IMAGE_TAG

:

$CI_REGISTRY_IMAGE:$CI_COMMIT_REF_SLUG

before_script

:

-

buildah login -u "$CI_REGISTRY_USER" -p "$CI_REGISTRY_PASSWORD" $CI_REGISTRY

oci-container-build

:

stage

:

build

script

:

-

buildah bud -t $IMAGE_TAG .

-

buildah push $IMAGE_TAG

when

:

manual

Specify which user runs the job

By default, the runner runs jobs as the root user within the container. To specify a different, non-root user to run the job, use the USER directive in the Dockerfile of the Docker image.

FROM

amazonlinux

RUN

[

"yum"

,

"install"

,

"-y"

,

"nginx"

]

RUN

[

"useradd"

,

"www"

]

USER

"www"

CMD

["/bin/bash"]

When you use that Docker image to execute your job, it runs as the specified user:

build

:

image

:

my/docker-build:image

script

:

-

whoami

# www

Configure how runners pull images

Configure the pull policy in the config.toml to define how runners pull Docker images from registries. You can set a single policy, a list of policies, or allow specific pull policies.

Use the following values for the pull_policy:

  • always: Pull an image even if a local image exists. Default.
  • if-not-present: Pull an image only when a local version does not exist.
  • never: Never pull an image and use only local images.

[[runners]]

(...)

executor

=

"docker"

[runners.docker]

(...)

pull_policy

=

"always"

# available: always, if-not-present, never

Set the always pull policy

The always option, which is on by default, always initiates a pull before
creating the container. This option makes sure the image is up-to-date, and
prevents you from using outdated images even if a local image exists.

Use this pull policy if:

  • Runners must always pull the most recent images.
  • Runners are publicly available and configured for auto-scale or as
    a shared runner in your GitLab instance.

Do not use this policy if runners must use locally stored images.

Set always as the pull policy in the config.toml:

[[runners]]

(...)

executor

=

"docker"

[runners.docker]

(...)

pull_policy

=

"always"

Set the if-not-present pull policy

When you set the pull policy to if-not-present, the runner first checks
if a local image exists. If there is no local image, the runner pulls
an image from the registry.

Use the if-not-present policy to:

  • Use local images but also pull images if a local image does not exist.
  • Reduce time that runners analyze the difference in image layers for heavy and rarely updated images.
    In this case, you must manually remove the image regularly from the local Docker Engine store to
    force the image update.

Do not use this policy:

  • For shared runners where different users that use the runner may have access to private images.
    For more information about security issues, see
    Usage of private Docker images with if-not-present pull policy.
  • If jobs are frequently updated and must be run in the most recent image
    version. This may result in a network load reduction that outweighs the value of frequent deletion
    of local images.

Set the if-not-present policy in the config.toml:

[[runners]]

(...)

executor

=

"docker"

[runners.docker]

(...)

pull_policy

=

"if-not-present"

Set the never pull policy

Prerequisites:

  • Local images must contain an installed Docker Engine and a local copy of used images.

When you set the pull policy to never, image pulling is disabled. Users can only use images
that have been manually pulled on the Docker host where the runner runs.

Use the never pull policy:

  • To control the images used by runner users.
  • For private runners that are dedicated to a project that can only use specific images
    that are not publicly available on any registries.

Do not use the never pull policy for auto-scaled
Docker executors. The never pull policy is usable only when using a pre-defined cloud instance
images for chosen cloud provider.

Set the never policy in the config.toml:

[[runners]]

(...)

executor

=

"docker"

[runners.docker]

(...)

pull_policy

=

"if-not-present"

Set multiple pull policies

Introduced in GitLab Runner 13.8.

You can list multiple pull policies to execute if a pull fails. The runner processes pull policies
in the order listed until a pull attempt is successful or the list is exhausted. For example, if a
runner uses the always pull policy and the registry is not available, you can add the if-not-present
as a second pull policy to use a locally cached Docker image.

For information about the security implications of this pull policy, see
Usage of private Docker images with if-not-present pull policy.

To set multiple pull policies, add them as a list in the config.toml:

[[runners]]

(...)

executor

=

"docker"

[runners.docker]

(...)

pull_policy

=

[

"always"

,

"if-not-present"

]

Allow Docker pull policies

Introduced in GitLab 15.1.

In the .gitlab-ci.yml file, you can specify a pull policy. This policy determines how a CI/CD job
fetches images.

To restrict which pull policies can be used in the .gitlab-ci.yml file, use allowed_pull_policies.

For example, to allow only the always and if-not-present pull policies, add them to the config.toml:

[[runners]]

(...)

executor

=

"docker"

[runners.docker]

(...)

allowed_pull_policies

=

[

"always"

,

"if-not-present"

]

  • If you don’t specify allowed_pull_policies, the default is the value in the pull_policy keyword.
  • If you don’t specify pull_policy, the default is always.
  • The existing pull_policy keyword must not
    include a pull policy that is not specified in allowed_pull_policies. If it does, the job returns an error.

Image pull error messages

Error messageDescription

Pulling docker image registry.tld/my/image:latest ... ERROR: Build failed: Error: image registry.tld/my/image:latest not foundThe runner cannot find the image. Displays when the always pull policy is set
Pulling docker image local_image:latest ... ERROR: Build failed: Error: image local_image:latest not foundThe image was built locally and doesn’t exist in any public or default Docker registry. Displays when the always pull policy is set.
Pulling docker image registry.tld/my/image:latest ... WARNING: Cannot pull the latest version of image registry.tld/my/image:latest : Error: image registry.tld/my/image:latest not found WARNING: Locally found image will be used instead.The runner has used a local image instead of pulling an image. Displays when the always pull policy is set in only GitLab Runner 1.8 and earlier.
Pulling docker image local_image:latest ... ERROR: Build failed: Error: image local_image:latest not foundThe image cannot be found locally. Displays when the never pull policy is set.
WARNING: Failed to pull image with policy "always": Error response from daemon: received unexpected HTTP status: 502 Bad Gateway (docker.go:143:0s) Attempt #2: Trying "if-not-present" pull policy Using locally found image version due to "if-not-present" pull policyThe runner failed to pull an image and attempts to pull an image by using the next listed pull policy. Displays when multiple pull policies are set.

Retry a failed pull

To configure a runner to retry a failed image pull, specify the same policy more than once in the
config.toml.

For example, this configuration retries the pull one time:

[runners.docker]

pull_policy

=

[

"always"

,

"always"

]

This setting is similar to the retry directive
in the .gitlab-ci.yml files of individual projects,
but only takes effect if specifically the Docker pull fails initially.

Docker vs Docker-SSH (and Docker+Machine vs Docker-SSH+Machine)

caution

Starting with GitLab Runner 10.0, both Docker-SSH and Docker-SSH+machine executors
are deprecated and will be removed in one of the upcoming releases.

We provided a support for a special type of Docker executor, namely Docker-SSH
(and the autoscaled version: Docker-SSH+Machine). Docker-SSH uses the same logic
as the Docker executor, but instead of executing the script directly, it uses an
SSH client to connect to the build container.

Docker-SSH then connects to the SSH server that is running inside the container
using its internal IP.

This executor is no longer maintained and will be removed in the near future.

Use Windows containers

Introduced in GitLab Runner 11.11.

To use Windows containers with the Docker executor, note the following
information about limitations, supported Windows versions, and
configuring a Windows Docker executor.

Nanoserver support

Introduced in GitLab Runner 13.6.

With the support for PowerShell Core introduced in the Windows helper image, it is now possible to leverage
the nanoserver variants for the helper image.

Limitations of Docker executor on Windows

The following are some limitations of using Windows containers with
Docker executor:

  • Docker-in-Docker is not supported, since it’s
    not supported by
    Docker itself.
  • Interactive web terminals are not supported.
  • Host device mounting not supported.
  • When mounting a volume directory it has to exist, or Docker will fail
    to start the container, see
    #3754 for
    additional detail.
  • docker-windows executor can be run only using GitLab Runner running
    on Windows.
  • Linux containers on Windows
    are not supported, since they are still experimental. Read
    the relevant issue for
    more details.
  • Because of a limitation in Docker,
    if the destination path drive letter is not c:, paths are not supported for:

    • builds_dir
    • cache_dir
    • volumes

    This means values such as f:\\cache_dir are not supported, but f: is supported.
    However, if the destination path is on the c: drive, paths are also supported
    (for example c:\\cache_dir).

Supported Windows versions

GitLab Runner only supports the following versions of Windows which
follows our support lifecycle for Windows:

  • Windows Server 21H1/LTSC2022.
  • Windows Server 20H2.
  • Windows Server 2004.
  • Windows Server 1809.

For future Windows Server versions, we have a
future version support policy.

You can only run containers based on the same OS version that the Docker
daemon is running on. For example, the following Windows Server Core images can
be used:

  • mcr.microsoft.com/windows/servercore:ltsc2022
  • mcr.microsoft.com/windows/servercore:ltsc2022-amd64
  • mcr.microsoft.com/windows/servercore:20H2
  • mcr.microsoft.com/windows/servercore:20H2-amd64
  • mcr.microsoft.com/windows/servercore:2004
  • mcr.microsoft.com/windows/servercore:2004-amd64
  • mcr.microsoft.com/windows/servercore:1809
  • mcr.microsoft.com/windows/servercore:1809-amd64
  • mcr.microsoft.com/windows/servercore:ltsc2019

Supported Docker versions

A Windows Server running GitLab Runner must be running a recent version of Docker
because GitLab Runner uses Docker to detect what version of Windows Server is running.

A known version of Docker that doesn’t work with GitLab Runner is Docker 17.06
since Docker does not identify the version of Windows Server resulting in the
following error:

unsupported Windows Version: Windows Server Datacenter

Read more about troubleshooting this.

Configure a Windows Docker executor

notec:\\cache
as a source directory when passing the --docker-volumes or
DOCKER_VOLUMES environment variable, there is a

When a runner is registered withas a source directory when passing theorenvironment variable, there is a known issue

Below is an example of the configuration for a simple Docker
executor running Windows.

[[runners]]

name

=

"windows-docker-2019"

url

=

"https://gitlab.com/"

token

=

"xxxxxxx"

executor

=

"docker-windows"

[runners.docker]

image

=

"mcr.microsoft.com/windows/servercore:1809_amd64"

volumes

=

[

"c:

\\

cache"

]

For other configuration options for the Docker executor, see the
advanced configuration
section.

Services

In GitLab Runner 12.9 and later,
you can use services by
enabling a network for each job.