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Commit e8c5c8e2 authored by Suzanne Selhorn's avatar Suzanne Selhorn Committed by Marcel Amirault
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Edited for style and clarity 

Related to: https://gitlab.com/gitlab-org/gitlab/-/issues/300312
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doc/ci/docker/using_docker_build.md
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......@@ -31,9 +31,9 @@ to learn more about how these runners are configured.
### Use the shell executor
You can include Docker commands in your CI/CD jobs if your runner is configured to
use the `shell` executor. The `gitlab-runner` user runs the Docker commands, but
needs permission to run them.
To include Docker commands in your CI/CD jobs, you can configure your runner to
use the `shell` executor. In this configuration, the `gitlab-runner` user runs
the Docker commands, but needs permission to do so.
1. [Install](https://gitlab.com/gitlab-org/gitlab-runner/#installation) GitLab Runner.
1. [Register](https://docs.gitlab.com/runner/register/) a runner.
......@@ -81,76 +81,70 @@ Learn more about the [security of the `docker` group](https://blog.zopyx.com/on-
### Use the Docker executor with the Docker image (Docker-in-Docker)
You can use "Docker-in-Docker" to run commands in your CI/CD jobs:
"Docker-in-Docker" (`dind`) means:
- Register a runner that uses the Docker executor.
- Use the [Docker image](https://hub.docker.com/_/docker/) provided by Docker to
run the jobs that need Docker commands.
- Your registered runner uses the [Docker executor](https://docs.gitlab.com/runner/executors/docker.html).
- The executor uses a [container image of Docker](https://hub.docker.com/_/docker/), provided
by Docker, to run your CI/CD jobs.
The Docker image has all of the `docker` tools installed
and can run the job script in context of the image in privileged mode.
The Docker image has all of the `docker` tools installed and can run
the job script in context of the image in privileged mode.
The `docker-compose` command is not available in this configuration by default.
To use `docker-compose` in your job scripts, follow the `docker-compose`
[installation instructions](https://docs.docker.com/compose/install/).
We recommend you use [Docker-in-Docker with TLS enabled](#docker-in-docker-with-tls-enabled),
which is supported by [GitLab.com shared runners](../../user/gitlab_com/index.md#shared-runners).
An example project that uses this approach can be found here: <https://gitlab.com/gitlab-examples/docker>.
WARNING:
When you enable `--docker-privileged`, you are effectively disabling all of
the security mechanisms of containers and exposing your host to privilege
escalation. Doing this can lead to container breakout. For more information, check
out the official Docker documentation on
[runtime privilege and Linux capabilities](https://docs.docker.com/engine/reference/run/#runtime-privilege-and-linux-capabilities).
You should always specify a specific version of the image, like `docker:19.03.12`.
If you use a tag like `docker:stable`, you have no control over which version is used.
Unpredictable behavior can result, especially when new versions are released.
#### Limitations of Docker-in-Docker
Docker-in-Docker is the recommended configuration, but it is
Docker-in-Docker is the recommended configuration, but is
not without its own challenges:
- When using Docker-in-Docker, each job is in a clean environment without the past
history. Concurrent jobs work fine because every build gets its own
instance of Docker engine so they don't conflict with each other. But this
also means that jobs can be slower because there's no caching of layers.
- By default, Docker 17.09 and higher uses `--storage-driver overlay2` which is
the recommended storage driver. See [Using the OverlayFS driver](#use-the-overlayfs-driver)
for details.
- Since the `docker:19.03.12-dind` container and the runner container don't share their
root file system, the job's working directory can be used as a mount point for
- **The `docker-compose` command**: This command is not available in this configuration by default.
To use `docker-compose` in your job scripts, follow the `docker-compose`
[installation instructions](https://docs.docker.com/compose/install/).
You can view a sample project that uses this approach here: <https://gitlab.com/gitlab-examples/docker>.
- **Cache**: Each job runs in a new environment. Concurrent jobs work fine,
because every build gets its own instance of Docker engine and they don't conflict with each other.
However, jobs can be slower because there's no caching of layers.
- **Storage drivers**: By default, earlier versions of Docker use the `vfs` storage driver,
which copies the file system for each job. Docker 17.09 and later use `--storage-driver overlay2`, which is
the recommended storage driver. See [Using the OverlayFS driver](#use-the-overlayfs-driver) for details.
- **Root file system**: Because the `docker:19.03.12-dind` container and the runner container don't share their
root file system, you can use the job's working directory as a mount point for
child containers. For example, if you have files you want to share with a
child container, you may create a subdirectory under `/builds/$CI_PROJECT_PATH`
and use it as your mount point (for a more thorough explanation, check [issue
#41227](https://gitlab.com/gitlab-org/gitlab-foss/-/issues/41227)):
child container, you might create a subdirectory under `/builds/$CI_PROJECT_PATH`
and use it as your mount point. For a more detailed explanation, view [issue
#41227](https://gitlab.com/gitlab-org/gitlab-foss/-/issues/41227).
```yaml
variables:
MOUNT_POINT: /builds/$CI_PROJECT_PATH/mnt
script:
- mkdir -p "$MOUNT_POINT"
- docker run -v "$MOUNT_POINT:/mnt" my-docker-image
```
In the examples below, we are using Docker images tags to specify a
specific version, such as `docker:19.03.12`. If tags like `docker:stable`
are used, you have no control over what version is used. This can lead to
unpredictable behavior, especially when new versions are
released.
#### Docker-in-Docker with TLS enabled
#### TLS enabled
> Introduced in GitLab Runner 11.11.
The Docker daemon supports connection over TLS and it's done by default
for Docker 19.03.12 or higher. This is the **suggested** way to use the
Docker-in-Docker service and
[GitLab.com shared runners](../../user/gitlab_com/index.md#shared-runners)
support this.
The Docker daemon supports connections over TLS. In Docker 19.03.12 and later,
TLS is the default.
##### Docker
WARNING:
This task enables `--docker-privileged`. When you do this, you are effectively disabling all of
the security mechanisms of containers and exposing your host to privilege
escalation. Doing this can lead to container breakout. For more information,
see the official Docker documentation about
[runtime privilege and Linux capabilities](https://docs.docker.com/engine/reference/run/#runtime-privilege-and-linux-capabilities).
> Introduced in GitLab Runner 11.11.
To use Docker-in-Docker with TLS enabled:
1. Install [GitLab Runner](https://docs.gitlab.com/runner/install/).
1. Register GitLab Runner from the command line to use `docker` and `privileged`
1. Register GitLab Runner from the command line. Use `docker` and `privileged`
mode:
```shell
......@@ -164,18 +158,16 @@ support this.
--docker-volumes "/certs/client"
```
The above command registers a new runner to use the special
`docker:19.03.12` image, which is provided by Docker. **Notice that it's
using the `privileged` mode to start the build and service
containers.** If you want to use [Docker-in-Docker](https://www.docker.com/blog/docker-can-now-run-within-docker/) mode, you always
have to use `privileged = true` in your Docker containers.
This also mounts `/certs/client` for the service and build
- This command registers a new runner to use the `docker:19.03.12` image.
To start the build and service containers, it uses the `privileged` mode.
If you want to use [Docker-in-Docker](https://www.docker.com/blog/docker-can-now-run-within-docker/),
you must always use `privileged = true` in your Docker containers.
- This command mounts `/certs/client` for the service and build
container, which is needed for the Docker client to use the
certificates inside of that directory. For more information on how
Docker with TLS works, check <https://hub.docker.com/_/docker/#tls>.
certificates in that directory. For more information on how
Docker with TLS works, see <https://hub.docker.com/_/docker/#tls>.
The above command creates a `config.toml` entry similar to this:
The previous command creates a `config.toml` entry similar to this:
```toml
[[runners]]
......@@ -193,14 +185,14 @@ support this.
[runners.cache.gcs]
```
1. You can now use `docker` in the build script (note the inclusion of the
`docker:19.03.12-dind` service):
1. You can now use `docker` in the job script. Note the inclusion of the
`docker:19.03.12-dind` service:
```yaml
image: docker:19.03.12
variables:
# When using dind service, we need to instruct docker to talk with
# When you use the dind service, you must instruct Docker to talk with
# the daemon started inside of the service. The daemon is available
# with a network connection instead of the default
# /var/run/docker.sock socket. Docker 19.03 does this automatically
......@@ -210,9 +202,9 @@ support this.
# The 'docker' hostname is the alias of the service container as described at
# https://docs.gitlab.com/ee/ci/docker/using_docker_images.html#accessing-the-services.
#
# Specify to Docker where to create the certificates, Docker will
# create them automatically on boot, and will create
# `/certs/client` that will be shared between the service and job
# Specify to Docker where to create the certificates. Docker
# creates them automatically on boot, and creates
# `/certs/client` to share between the service and job
# container, thanks to volume mount from config.toml
DOCKER_TLS_CERTDIR: "/certs"
......@@ -229,10 +221,12 @@ support this.
- docker run my-docker-image /script/to/run/tests
```
##### Kubernetes
#### Docker-in-Docker with TLS enabled in Kubernetes
> [Introduced](https://gitlab.com/gitlab-org/charts/gitlab-runner/-/issues/106) in GitLab Runner Helm Chart 0.23.0.
To use Docker-in-Docker with TLS enabled in Kubernetes:
1. Using the
[Helm chart](https://docs.gitlab.com/runner/install/kubernetes.html), update the
[`values.yml` file](https://gitlab.com/gitlab-org/charts/gitlab-runner/-/blob/00c1a2098f303dffb910714752e9a981e119f5b5/values.yaml#L133-137)
......@@ -251,14 +245,14 @@ support this.
medium = "Memory"
```
1. You can now use `docker` in the build script (note the inclusion of the
`docker:19.03.13-dind` service):
1. You can now use `docker` in the job script. Note the inclusion of the
`docker:19.03.13-dind` service:
```yaml
image: docker:19.03.13
variables:
# When using dind service, we need to instruct docker to talk with
# When using dind service, you must instruct Docker to talk with
# the daemon started inside of the service. The daemon is available
# with a network connection instead of the default
# /var/run/docker.sock socket.
......@@ -271,9 +265,9 @@ support this.
# Kubernetes executor connects services to the job container
# DOCKER_HOST: tcp://localhost:2376
#
# Specify to Docker where to create the certificates, Docker will
# create them automatically on boot, and will create
# `/certs/client` that will be shared between the service and job
# Specify to Docker where to create the certificates. Docker
# creates them automatically on boot, and creates
# `/certs/client` to share between the service and job
# container, thanks to volume mount from config.toml
DOCKER_TLS_CERTDIR: "/certs"
# These are usually specified by the entrypoint, however the
......@@ -295,9 +289,9 @@ support this.
- docker run my-docker-image /script/to/run/tests
```
#### TLS disabled
#### Docker-in-Docker with TLS disabled
Sometimes there are legitimate reasons why you might want to disable TLS.
Sometimes you might have legitimate reasons to disable TLS.
For example, you have no control over the GitLab Runner configuration
that you are using.
......@@ -319,14 +313,14 @@ Assuming that the runner's `config.toml` is similar to:
[runners.cache.gcs]
```
You can now use `docker` in the build script (note the inclusion of the
`docker:19.03.12-dind` service):
You can now use `docker` in the job script. Note the inclusion of the
`docker:19.03.12-dind` service:
```yaml
image: docker:19.03.12
variables:
# When using dind service we need to instruct docker, to talk with the
# When using dind service, you must instruct docker to talk with the
# daemon started inside of the service. The daemon is available with
# a network connection instead of the default /var/run/docker.sock socket.
#
......@@ -340,7 +334,7 @@ variables:
#
DOCKER_HOST: tcp://docker:2375
#
# This will instruct Docker not to start over TLS.
# This instructs Docker not to start over TLS.
DOCKER_TLS_CERTDIR: ""
services:
......@@ -382,10 +376,10 @@ To make Docker available in the context of the image:
--docker-volumes /var/run/docker.sock:/var/run/docker.sock
```
This command registers a new runner to use the special
`docker:19.03.12` image, which is provided by Docker. **The command uses
This command registers a new runner to use the
`docker:19.03.12` image provided by Docker. The command uses
the Docker daemon of the runner itself. Any containers spawned by Docker
commands are siblings of the runner rather than children of the runner.**
commands are siblings of the runner rather than children of the runner.
This may have complications and limitations that are unsuitable for your workflow.
Your `config.toml` file should now have an entry like this:
......@@ -405,7 +399,7 @@ To make Docker available in the context of the image:
Insecure = false
```
1. Use `docker` in the build script. You don't need to
1. Use `docker` in the job script. You don't need to
include the `docker:19.03.12-dind` service, like you do when you're using
the Docker-in-Docker executor:
......@@ -445,9 +439,9 @@ the implications of this method are:
When the Docker daemon starts inside of the service container, it uses
the default configuration. You may want to configure a [registry
mirror](https://docs.docker.com/registry/recipes/mirror/) for
performance improvements and ensuring you don't reach DockerHub rate limits.
performance improvements and to ensure you don't reach Docker Hub rate limits.
##### Inside `.gitlab-ci.yml`
##### The service in the `.gitlab-ci.yml` file
You can append extra CLI flags to the `dind` service to set the registry
mirror:
......@@ -455,10 +449,10 @@ mirror:
```yaml
services:
- name: docker:19.03.13-dind
command: ["--registry-mirror", "https://registry-mirror.example.com"] # Specify the registry mirror to use.
command: ["--registry-mirror", "https://registry-mirror.example.com"] # Specify the registry mirror to use
```
##### DinD service defined inside of GitLab Runner configuration
##### The service in the GitLab Runner configuration file
> [Introduced](https://gitlab.com/gitlab-org/gitlab-runner/-/issues/27173) in GitLab Runner 13.6.
......@@ -495,7 +489,7 @@ Kubernetes:
command = ["--registry-mirror", "https://registry-mirror.example.com"]
```
##### Docker executor inside GitLab Runner configuration
##### The Docker executor in the GitLab Runner configuration file
If you are a GitLab Runner administrator, you can use
the mirror for every `dind` service. Update the
......@@ -528,7 +522,7 @@ picked up by the `dind` service.
volumes = ["/opt/docker/daemon.json:/etc/docker/daemon.json:ro"]
```
##### Kubernetes executor inside GitLab Runner configuration
##### The Kubernetes executor in the GitLab Runner configuration file
> [Introduced](https://gitlab.com/gitlab-org/gitlab-runner/-/issues/3223) in GitLab Runner 13.6.
......@@ -556,7 +550,7 @@ kubectl create configmap docker-daemon --namespace gitlab-runner --from-file /tm
```
NOTE:
Make sure to use the namespace that GitLab Runner Kubernetes executor uses
Make sure to use the namespace that the GitLab Runner Kubernetes executor uses
to create job pods in.
After the ConfigMap is created, you can update the `config.toml`
......@@ -577,15 +571,15 @@ The configuration is picked up by the `dind` service.
sub_path = "daemon.json"
```
## Authenticating with registry in Docker-in-Docker
## Authenticate with registry in Docker-in-Docker
When you use Docker-in-Docker, the [normal authentication
methods](using_docker_images.html#define-an-image-from-a-private-container-registry)
When you use Docker-in-Docker, the
[standard authentication methods](using_docker_images.md#define-an-image-from-a-private-container-registry)
don't work because a fresh Docker daemon is started with the service.
### Option 1: Run `docker login`
In [`before_script`](../yaml/README.md#before_script) run `docker
In [`before_script`](../yaml/README.md#before_script), run `docker
login`:
```yaml
......@@ -618,7 +612,7 @@ are using the official `docker:19.03.13` image, the home directory is
under `/root`.
If you mount the configuration file, any `docker` command
that modifies the `~/.docker/config.json` (for example, `docker login`)
that modifies the `~/.docker/config.json` fails. For example, `docker login`
fails, because the file is mounted as read-only. Do not change it from
read-only, because problems occur.
......@@ -638,8 +632,8 @@ documentation:
#### Docker
Update the [volume
mounts](https://docs.gitlab.com/runner/configuration/advanced-configuration.html#volumes-in-the-runnersdocker-section)
Update the
[volume mounts](https://docs.gitlab.com/runner/configuration/advanced-configuration.html#volumes-in-the-runnersdocker-section)
to include the file.
```toml
......@@ -661,8 +655,7 @@ of this file. You can do this with a command like:
kubectl create configmap docker-client-config --namespace gitlab-runner --from-file /opt/.docker/config.json
```
Update the [volume
mounts](https://docs.gitlab.com/runner/executors/kubernetes.html#using-volumes)
Update the [volume mounts](https://docs.gitlab.com/runner/executors/kubernetes.html#using-volumes)
to include the file.
```toml
......@@ -687,17 +680,15 @@ If you already have
defined, you can use the variable and save it in
`~/.docker/config.json`.
There are multiple ways to define this. For example:
There are multiple ways to define this authentication:
- Inside
[`pre_build_script`](https://docs.gitlab.com/runner/configuration/advanced-configuration.html#the-runners-section)
inside of the runner configuration file.
- Inside [`before_script`](../yaml/README.md#before_script).
- Inside of [`script`](../yaml/README.md#script).
- In [`pre_build_script`](https://docs.gitlab.com/runner/configuration/advanced-configuration.html#the-runners-section)
in the runner configuration file.
- In [`before_script`](../yaml/README.md#before_script).
- In [`script`](../yaml/README.md#script).
Below is an example of
[`before_script`](../yaml/README.md#before_script). The same commands
apply for any solution you implement.
The following example shows [`before_script`](../yaml/README.md#before_script).
The same commands apply for any solution you implement.
```yaml
image: docker:19.03.13
......@@ -718,10 +709,10 @@ build:
- docker run my-docker-image /script/to/run/tests
```
## Making Docker-in-Docker builds faster with Docker layer caching
## Make Docker-in-Docker builds faster with Docker layer caching
When using Docker-in-Docker, Docker downloads all layers of your image every
time you create a build. Recent versions of Docker (Docker 1.13 and above) can
time you create a build. Recent versions of Docker (Docker 1.13 and later) can
use a pre-existing image as a cache during the `docker build` step. This considerably
speeds up the build process.
......@@ -737,9 +728,9 @@ as a cache source by using multiple `--cache-from` arguments. Any image that's u
with the `--cache-from` argument must first be pulled
(using `docker pull`) before it can be used as a cache source.
### Using Docker caching
### Docker caching example
Here's a `.gitlab-ci.yml` file showing how Docker caching can be used:
Here's a `.gitlab-ci.yml` file that shows how to use Docker caching:
```yaml
image: docker:19.03.12
......@@ -764,12 +755,12 @@ build:
- docker push $CI_REGISTRY_IMAGE:latest
```
The steps in the `script` section for the `build` stage can be summed up to:
In the `script` section for the `build` stage:
1. The first command tries to pull the image from the registry so that it can be
used as a cache for the `docker build` command.
1. The second command builds a Docker image using the pulled image as a
cache (notice the `--cache-from $CI_REGISTRY_IMAGE:latest` argument) if
1. The second command builds a Docker image by using the pulled image as a
cache (see the `--cache-from $CI_REGISTRY_IMAGE:latest` argument) if
available, and tags it.
1. The last two commands push the tagged Docker images to the container registry
so that they may also be used as cache for subsequent builds.
......@@ -818,10 +809,10 @@ variables:
### Use the OverlayFS driver for every project
If you use your own [GitLab Runners](https://docs.gitlab.com/runner/), you
If you use your own [runners](https://docs.gitlab.com/runner/), you
can enable the driver for every project by setting the `DOCKER_DRIVER`
environment variable in the
[`[[runners]]` section of `config.toml`](https://docs.gitlab.com/runner/configuration/advanced-configuration.html#the-runners-section):
[`[[runners]]` section of the `config.toml` file](https://docs.gitlab.com/runner/configuration/advanced-configuration.html#the-runners-section):
```toml
environment = ["DOCKER_DRIVER=overlay2"]
......@@ -832,7 +823,7 @@ If you're running multiple runners, you have to modify all configuration files.
Read more about the [runner configuration](https://docs.gitlab.com/runner/configuration/)
and [using the OverlayFS storage driver](https://docs.docker.com/engine/userguide/storagedriver/overlayfs-driver/).
## Using the GitLab Container Registry
## Use the GitLab Container Registry
After you've built a Docker image, you can push it up to the built-in
[GitLab Container Registry](../../user/packages/container_registry/index.md#build-and-push-by-using-gitlab-cicd).
......@@ -842,13 +833,12 @@ After you've built a Docker image, you can push it up to the built-in
### `docker: Cannot connect to the Docker daemon at tcp://docker:2375. Is the docker daemon running?`
This is a common error when you are using
[Docker in Docker](#use-the-docker-executor-with-the-docker-image-docker-in-docker)
v19.03 or higher.
[Docker-in-Docker](#use-the-docker-executor-with-the-docker-image-docker-in-docker)
v19.03 or later.
This occurs because Docker starts on TLS automatically, so you need to do some setup.
If:
This issue occurs because Docker starts on TLS automatically.
- This is the first time setting it up, carefully read
[using Docker in Docker workflow](#use-the-docker-executor-with-the-docker-image-docker-in-docker).
- You are upgrading from v18.09 or earlier, read our
- If this is your first time setting it up, read
[use the Docker executor with the Docker image](#use-the-docker-executor-with-the-docker-image-docker-in-docker).
- If you are upgrading from v18.09 or earlier, read our
[upgrade guide](https://about.gitlab.com/blog/2019/07/31/docker-in-docker-with-docker-19-dot-03/).
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