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Dockerfile

It all starts with a Dockerfile.

Docker builds images by reading the instructions from a Dockerfile. This is a text file containing instructions that adhere to a specific format needed to assemble your application into a container image and for which you can find its specification reference in the Dockerfile reference.

Here are the most common types of instructions:

Instruction	Description
`FROM <image>`	Defines a base for your image.
`RUN <command>`	Executes any commands in a new layer on top of the current image and commits the result. `RUN` also has a shell form for running commands.
`WORKDIR <directory>`	Sets the working directory for any `RUN` , `CMD` , `ENTRYPOINT` , `COPY` , and `ADD` instructions that follow it in the Dockerfile.
`COPY <src> <dest>`	Copies new files or directories from `<src>` and adds them to the filesystem of the container at the path `<dest>` .
`CMD <command>`	Lets you define the default program that is run once you start the container based on this image. Each Dockerfile only has one `CMD` , and only the last `CMD` instance is respected when multiple exist.

Dockerfiles are crucial inputs for image builds and can facilitate automated, multi-layer image builds based on your unique configurations. Dockerfiles can start simple and grow with your needs and support images that require complex instructions. For all the possible instructions, see the Dockerfile reference.

The default filename to use for a Dockerfile is Dockerfile , without a file extension. Using the default name allows you to run the docker build command without having to specify additional command flags.

Some projects may need distinct Dockerfiles for specific purposes. A common convention is to name these <something>.Dockerfile . Such Dockerfiles can then be used through the --file (or -f shorthand) option on the docker build command. Refer to the âSpecify a Dockerfileâ section in the docker build reference to learn about the --file option.

Note

We recommend using the default ( Dockerfile ) for your projectâs primary Dockerfile.

Docker images consist of read-only layers , each resulting from an instruction in the Dockerfile. Layers are stacked sequentially and each one is a delta representing the changes applied to the previous layer.

Example

Hereâs a simple Dockerfile example to get you started with building images. Weâll take a simple âHello Worldâ Python Flask application, and bundle it into a Docker image that can test locally or deploy anywhere!

Letâs say we have a hello.py file with the following content:

   from flask import Flask
app = Flask(__name__)

@app.route("/")
def hello():
    return "Hello World!"

  

Donât worry about understanding the full example if youâre not familiar with Python, itâs just a simple web server that will contain a single page that says âHello Worldâ.

Note

If you test the example, make sure to copy over the indentation as well! For more information about this sample Flask application, check the Flask Quickstart page.

Hereâs the Dockerfile that will be used to create an image for our application:

   # syntax=docker/dockerfile:1
FROM ubuntu:22.04

# install app dependencies
RUN apt-get update && apt-get install -y python3 python3-pip
RUN pip install flask==2.1.*

# install app
COPY hello.py /

# final configuration
ENV FLASK_APP=hello
EXPOSE 8000
CMD flask run --host 0.0.0.0 --port 8000

  

The first line to add to a Dockerfile is a # syntax parser directive. While optional, this directive instructs the Docker builder what syntax to use when parsing the Dockerfile, and allows older Docker versions with BuildKit enabled to use a specific Dockerfile frontend before starting the build. Parser directives must appear before any other comment, whitespace, or Dockerfile instruction in your Dockerfile, and should be the first line in Dockerfiles.

# syntax=docker/dockerfile:1

Note

We recommend using docker/dockerfile:1 , which always points to the latest release of the version 1 syntax. BuildKit automatically checks for updates of the syntax before building, making sure you are using the most current version.

Next we define the first instruction:

FROM ubuntu:22.04

Here the FROM instruction sets our base image to the 22.04 release of Ubuntu. All following instructions are executed on this base image, in this case, an Ubuntu environment. The notation ubuntu:22.04 , follows the name:tag standard for naming docker images. When you build your image you use this notation to name your images and use it to specify any existing Docker image. There are many public images you can leverage in your projects. Explore Docker Hub to find out.

   # install app dependencies
RUN apt-get update && apt-get install -y python3 python3-pip

This RUN instruction executes a shell command in the build context.

In this example, our context is a full Ubuntu operating system, so we have access to its package manager, apt. The provided commands update our package lists and then, after that succeeds, installs python3 and pip , the package manager for Python.

Also note # install app dependencies line. This is a comment. Comments in Dockerfiles begin with the # symbol. As your Dockerfile evolves, comments can be instrumental to document how your dockerfile works for any future readers and editors of the file.

Note

Starting your Dockerfile by a # like regular comments is treated as a directive when you are using BuildKit (default), otherwise it is ignored.

   RUN pip install flask==2.1.*

  

This second RUN instruction requires that weâve installed pip in the layer before. After applying the previous directive, we can use the pip command to install the flask web framework. This is the framework weâve used to write our basic âHello Worldâ application from above, so to run it in Docker, weâll need to make sure itâs installed.

COPY hello.py /

Now we use the COPY instruction to copy our hello.py file from the local build context into the root directory of our image. After being executed, weâll end up with a file called /hello.py inside the image.

ENV FLASK_APP=hello

This ENV instruction sets a Linux environment variable weâll need later. This is a flask-specific variable, that configures the command later used to run our hello.py application. Without this, flask wouldnât know where to find our application to be able to run it.

EXPOSE 8000

This EXPOSE instruction marks that our final image has a service listening on port 8000 . This isnât required, but it is a good practice, as users and tools can use this to understand what your image does.

CMD flask run --host 0.0.0.0 --port 8000

Finally, CMD instruction sets the command that is run when the user starts a container based on this image. In this case weâll start the flask development server listening on all addresses on port 8000 .

Testing

To test our Dockerfile, weâll first build it using the docker build command:

   $ docker build -t test:latest .

  

Here -t test:latest option specifies the name (required) and tag (optional) of the image weâre building. . specifies the build context as the current directory. In this example, this is where build expects to find the Dockerfile and the local files the Dockerfile needs to access, in this case your Python application.

So, in accordance with the build command issued and how build context works, your Dockerfile and python app need to be in the same directory.

Now run your newly built image:

   $ docker run -p 8000:8000 test:latest

  

From your computer, open a browser and navigate to http://localhost:8000

Note

You can also build and run using Play with Docker that provides you with a temporary Docker instance in the cloud.

Other resources

If you are interested in examples in other languages, such as Go, check out our language-specific guides in the Guides section.

Color output controls

BuildKit and Buildx have support for modifying the colors that are used to output information to the terminal. You can set the environment variable BUILDKIT_COLORS to something like run=123,20,245:error=yellow:cancel=blue:warning=white to set the colors that you would like to use:

Progress output custom colors

Setting NO_COLOR to anything will disable any colorized output as recommended by no-color.org:

Progress output no color

Note

Parsing errors will be reported but ignored. This will result in default color values being used where needed.

See also the list of pre-defined colors.

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Configure BuildKit

If you create a docker-container or kubernetes builder with Buildx, you can apply a custom BuildKit configuration by passing the --config flag to the docker buildx create command.

Registry mirror

You can define a registry mirror to use for your builds. Doing so redirects BuildKit to pull images from a different hostname. The following steps exemplify defining a mirror for docker.io (Docker Hub) to mirror.gcr.io .

Create a TOML at /etc/buildkitd.toml with the following content:
```
debug = true
[registry."docker.io"]
  mirrors = ["mirror.gcr.io"]
```
Note

debug = true turns on debug requests in the BuildKit daemon, which logs a message that shows when a mirror is being used.

Create a docker-container builder that uses this BuildKit configuration:

     $ docker buildx create --use --bootstrap \
  --name mybuilder \
  --driver docker-container \
  --config /etc/buildkitd.toml

    

Build an image:

     docker buildx build --load . -f - <<EOF
FROM alpine
RUN echo "hello world"
EOF

    

The BuildKit logs for this builder now shows that it uses the GCR mirror. You can tell by the fact that the response messages include the x-goog-* HTTP headers.

$ docker logs buildx_buildkit_mybuilder0

   ...
time="2022-02-06T17:47:48Z" level=debug msg="do request" request.header.accept="application/vnd.docker.container.image.v1+json, */*" request.header.user-agent=containerd/1.5.8+unknown request.method=GET spanID=9460e5b6e64cec91 traceID=b162d3040ddf86d6614e79c66a01a577
time="2022-02-06T17:47:48Z" level=debug msg="fetch response received" response.header.accept-ranges=bytes response.header.age=1356 response.header.alt-svc="h3=\":443\"; ma=2592000,h3-29=\":443\"; ma=2592000,h3-Q050=\":443\"; ma=2592000,h3-Q046=\":443\"; ma=2592000,h3-Q043=\":443\"; ma=2592000,quic=\":443\"; ma=2592000; v=\"46,43\"" response.header.cache-control="public, max-age=3600" response.header.content-length=1469 response.header.content-type=application/octet-stream response.header.date="Sun, 06 Feb 2022 17:25:17 GMT" response.header.etag="\"774380abda8f4eae9a149e5d5d3efc83\"" response.header.expires="Sun, 06 Feb 2022 18:25:17 GMT" response.header.last-modified="Wed, 24 Nov 2021 21:07:57 GMT" response.header.server=UploadServer response.header.x-goog-generation=1637788077652182 response.header.x-goog-hash="crc32c=V3DSrg==" response.header.x-goog-hash.1="md5=d0OAq9qPTq6aFJ5dXT78gw==" response.header.x-goog-metageneration=1 response.header.x-goog-storage-class=STANDARD response.header.x-goog-stored-content-encoding=identity response.header.x-goog-stored-content-length=1469 response.header.x-guploader-uploadid=ADPycduqQipVAXc3tzXmTzKQ2gTT6CV736B2J628smtD1iDytEyiYCgvvdD8zz9BT1J1sASUq9pW_ctUyC4B-v2jvhIxnZTlKg response.status="200 OK" spanID=9460e5b6e64cec91 traceID=b162d3040ddf86d6614e79c66a01a577
time="2022-02-06T17:47:48Z" level=debug msg="fetch response received" response.header.accept-ranges=bytes response.header.age=760 response.header.alt-svc="h3=\":443\"; ma=2592000,h3-29=\":443\"; ma=2592000,h3-Q050=\":443\"; ma=2592000,h3-Q046=\":443\"; ma=2592000,h3-Q043=\":443\"; ma=2592000,quic=\":443\"; ma=2592000; v=\"46,43\"" response.header.cache-control="public, max-age=3600" response.header.content-length=1471 response.header.content-type=application/octet-stream response.header.date="Sun, 06 Feb 2022 17:35:13 GMT" response.header.etag="\"35d688bd15327daafcdb4d4395e616a8\"" response.header.expires="Sun, 06 Feb 2022 18:35:13 GMT" response.header.last-modified="Wed, 24 Nov 2021 21:07:12 GMT" response.header.server=UploadServer response.header.x-goog-generation=1637788032100793 response.header.x-goog-hash="crc32c=aWgRjA==" response.header.x-goog-hash.1="md5=NdaIvRUyfar8201DleYWqA==" response.header.x-goog-metageneration=1 response.header.x-goog-storage-class=STANDARD response.header.x-goog-stored-content-encoding=identity response.header.x-goog-stored-content-length=1471 response.header.x-guploader-uploadid=ADPycdtR-gJYwC7yHquIkJWFFG8FovDySvtmRnZBqlO3yVDanBXh_VqKYt400yhuf0XbQ3ZMB9IZV2vlcyHezn_Pu3a1SMMtiw response.status="200 OK" spanID=9460e5b6e64cec91 traceID=b162d3040ddf86d6614e79c66a01a577
time="2022-02-06T17:47:48Z" level=debug msg=fetch spanID=9460e5b6e64cec91 traceID=b162d3040ddf86d6614e79c66a01a577
time="2022-02-06T17:47:48Z" level=debug msg=fetch spanID=9460e5b6e64cec91 traceID=b162d3040ddf86d6614e79c66a01a577
time="2022-02-06T17:47:48Z" level=debug msg=fetch spanID=9460e5b6e64cec91 traceID=b162d3040ddf86d6614e79c66a01a577
time="2022-02-06T17:47:48Z" level=debug msg=fetch spanID=9460e5b6e64cec91 traceID=b162d3040ddf86d6614e79c66a01a577
time="2022-02-06T17:47:48Z" level=debug msg="do request" request.header.accept="application/vnd.docker.image.rootfs.diff.tar.gzip, */*" request.header.user-agent=containerd/1.5.8+unknown request.method=GET spanID=9460e5b6e64cec91 traceID=b162d3040ddf86d6614e79c66a01a577
time="2022-02-06T17:47:48Z" level=debug msg="fetch response received" response.header.accept-ranges=bytes response.header.age=1356 response.header.alt-svc="h3=\":443\"; ma=2592000,h3-29=\":443\"; ma=2592000,h3-Q050=\":443\"; ma=2592000,h3-Q046=\":443\"; ma=2592000,h3-Q043=\":443\"; ma=2592000,quic=\":443\"; ma=2592000; v=\"46,43\"" response.header.cache-control="public, max-age=3600" response.header.content-length=2818413 response.header.content-type=application/octet-stream response.header.date="Sun, 06 Feb 2022 17:25:17 GMT" response.header.etag="\"1d55e7be5a77c4a908ad11bc33ebea1c\"" response.header.expires="Sun, 06 Feb 2022 18:25:17 GMT" response.header.last-modified="Wed, 24 Nov 2021 21:07:06 GMT" response.header.server=UploadServer response.header.x-goog-generation=1637788026431708 response.header.x-goog-hash="crc32c=ZojF+g==" response.header.x-goog-hash.1="md5=HVXnvlp3xKkIrRG8M+vqHA==" response.header.x-goog-metageneration=1 response.header.x-goog-storage-class=STANDARD response.header.x-goog-stored-content-encoding=identity response.header.x-goog-stored-content-length=2818413 response.header.x-guploader-uploadid=ADPycdsebqxiTBJqZ0bv9zBigjFxgQydD2ESZSkKchpE0ILlN9Ibko3C5r4fJTJ4UR9ddp-UBd-2v_4eRpZ8Yo2llW_j4k8WhQ response.status="200 OK" spanID=9460e5b6e64cec91 traceID=b162d3040ddf86d6614e79c66a01a577
...

  

Setting registry certificates

If you specify registry certificates in the BuildKit configuration, the daemon copies the files into the container under /etc/buildkit/certs . The following steps show adding a self-signed registry certificate to the BuildKit configuration.

Add the following configuration to /etc/buildkitd.toml :

     # /etc/buildkitd.toml
debug = true
[registry."myregistry.com"]
  ca=["/etc/certs/myregistry.pem"]
  [[registry."myregistry.com".keypair]]
    key="/etc/certs/myregistry_key.pem"
    cert="/etc/certs/myregistry_cert.pem"

    

This tells the builder to push images to the myregistry.com registry using the certificates in the specified location ( /etc/certs ).

Create a docker-container builder that uses this configuration:

     $ docker buildx create --use --bootstrap \
  --name mybuilder \
  --driver docker-container \
  --config /etc/buildkitd.toml

    

Inspect the builderâs configuration file ( /etc/buildkit/buildkitd.toml ), it shows that the certificate configuration is now configured in the builder.

     $ docker exec -it buildx_buildkit_mybuilder0 cat /etc/buildkit/buildkitd.toml

    

     debug = true

[registry]

  [registry."myregistry.com"]
    ca = ["/etc/buildkit/certs/myregistry.com/myregistry.pem"]

    [[registry."myregistry.com".keypair]]
      cert = "/etc/buildkit/certs/myregistry.com/myregistry_cert.pem"
      key = "/etc/buildkit/certs/myregistry.com/myregistry_key.pem"

Verify that the certificates are inside the container:

     $ docker exec -it buildx_buildkit_mybuilder0 ls /etc/buildkit/certs/myregistry.com/
myregistry.pem    myregistry_cert.pem   myregistry_key.pem

Now you can push to the registry using this builder, and it will authenticate using the certificates:

   $ docker buildx build --push --tag myregistry.com/myimage:latest .

  

CNI networking

CNI networking for builders can be useful for dealing with network port contention during concurrent builds. CNI is not yet available in the default BuildKit image. But you can create your own image that includes CNI support.

The following Dockerfile example shows a custom BuildKit image with CNI support. It uses the CNI config for integration tests in BuildKit as an example. Feel free to include your own CNI configuration.

   # syntax=docker/dockerfile:1

ARG BUILDKIT_VERSION=v{{ site.buildkit_version }}
ARG CNI_VERSION=v1.0.1

FROM --platform=$BUILDPLATFORM alpine AS cni-plugins
RUN apk add --no-cache curl
ARG CNI_VERSION
ARG TARGETOS
ARG TARGETARCH
WORKDIR /opt/cni/bin
RUN curl -Ls https://github.com/containernetworking/plugins/releases/download/$CNI_VERSION/cni-plugins-$TARGETOS-$TARGETARCH-$CNI_VERSION.tgz | tar xzv

FROM moby/buildkit:${BUILDKIT_VERSION}
ARG BUILDKIT_VERSION
RUN apk add --no-cache iptables
COPY --from=cni-plugins /opt/cni/bin /opt/cni/bin
ADD https://raw.githubusercontent.com/moby/buildkit/${BUILDKIT_VERSION}/hack/fixtures/cni.json /etc/buildkit/cni.json

  

Now you can build this image, and create a builder instance from it using the --driver-opt image option:

   $ docker buildx build --tag buildkit-cni:local --load .
$ docker buildx create --use --bootstrap \
  --name mybuilder \
  --driver docker-container \
  --driver-opt "image=buildkit-cni:local" \
  --buildkitd-flags "--oci-worker-net=cni"

  

Resource limiting

Max parallelism

You can limit the parallelism of the BuildKit solver, which is particularly useful for low-powered machines, using a BuildKit configuration while creating a builder with the --config flags.

   # /etc/buildkitd.toml
[worker.oci]
  max-parallelism = 4

  

Now you can create a docker-container builder that will use this BuildKit configuration to limit parallelism.

   $ docker buildx create --use \
  --name mybuilder \
  --driver docker-container \
  --config /etc/buildkitd.toml

  

TCP connection limit

TCP connections are limited to 4 simultaneous connections per registry for pulling and pushing images, plus one additional connection dedicated to metadata requests. This connection limit prevents your build from getting stuck while pulling images. The dedicated metadata connection helps reduce the overall build time.

More information: moby/buildkit#2259

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Custom Dockerfile syntax

Dockerfile frontend

BuildKit supports loading frontends dynamically from container images. To use an external Dockerfile frontend, the first line of your Dockerfile needs to set the syntax directive pointing to the specific image you want to use:

# syntax=[remote image reference]

For example:

   # syntax=docker/dockerfile:1
# syntax=docker.io/docker/dockerfile:1
# syntax=example.com/user/repo:tag@sha256:abcdef...

  

This defines the location of the Dockerfile syntax that is used to build the Dockerfile. The BuildKit backend allows seamlessly using external implementations that are distributed as Docker images and execute inside a container sandbox environment.

Custom Dockerfile implementations allow you to:

Automatically get bugfixes without updating the Docker daemon
Make sure all users are using the same implementation to build your Dockerfile
Use the latest features without updating the Docker daemon
Try out new features or third-party features before they are integrated in the Docker daemon
Use alternative build definitions, or create your own

Note

BuildKit also ships with a built-in Dockerfile frontend, but itâs recommended to use an external image to make sure that all users use the same version on the builder and to pick up bugfixes automatically without waiting for a new version of BuildKit or Docker Engine.

Official releases

Docker distributes official versions of the images that can be used for building Dockerfiles under docker/dockerfile repository on Docker Hub. There are two channels where new images are released: stable and labs .

Stable channel

The stable channel follows semantic versioning. For example:

docker/dockerfile:1 - kept updated with the latest 1.x.x minor and patch release.
docker/dockerfile:1.2 - kept updated with the latest 1.2.x patch release, and stops receiving updates once version 1.3.0 is released.
docker/dockerfile:1.2.1 - immutable: never updated.

We recommend using docker/dockerfile:1 , which always points to the latest stable release of the version 1 syntax, and receives both âminorâ and âpatchâ updates for the version 1 release cycle. BuildKit automatically checks for updates of the syntax when performing a build, making sure you are using the most current version.

If a specific version is used, such as 1.2 or 1.2.1 , the Dockerfile needs to be updated manually to continue receiving bugfixes and new features. Old versions of the Dockerfile remain compatible with the new versions of the builder.

Labs channel

The labs channel provides early access to Dockerfile features that are not yet available in the stable channel. labs images are released at the same time as stable releases, and follow the same version pattern, but use the -labs suffix, for example:

docker/dockerfile:labs - latest release on labs channel.
docker/dockerfile:1-labs - same as dockerfile:1 , with experimental features enabled.
docker/dockerfile:1.2-labs - same as dockerfile:1.2 , with experimental features enabled.
docker/dockerfile:1.2.1-labs - immutable: never updated. Same as dockerfile:1.2.1 , with experimental features enabled.

Choose a channel that best fits your needs. If you want to benefit from new features, use the labs channel. Images in the labs channel contain all the features in the stable channel, plus early access features. Stable features in the labs channel follow semantic versioning, but early access features donât, and newer releases may not be backwards compatible. Pin the version to avoid having to deal with breaking changes.

Other resources

For documentation on âlabsâ features, master builds, and nightly feature releases, refer to the description in the BuildKit source repository on GitHub. For a full list of available images, visit the docker/dockerfile repository on Docker Hub, and the docker/dockerfile-upstream repository on Docker Hub for development builds.

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BuildKit

Overview

BuildKit is an improved backend to replace the legacy builder. It comes with new and much improved functionality for improving your buildsâ performance and the reusability of your Dockerfiles. It also introduces support for handling more complex scenarios:

Detect and skip executing unused build stages
Parallelize building independent build stages
Incrementally transfer only the changed files in your build context between builds
Detect and skip transferring unused files in your build context
Use Dockerfile frontend implementations with many new features
Avoid side effects with rest of the API (intermediate images and containers)
Prioritize your build cache for automatic pruning

Apart from many new features, the main areas BuildKit improves on the current experience are performance, storage management, and extensibility. From the performance side, a significant update is a new fully concurrent build graph solver. It can run build steps in parallel when possible and optimize out commands that donât have an impact on the final result. We have also optimized the access to the local source files. By tracking only the updates made to these files between repeated build invocations, there is no need to wait for local files to be read or uploaded before the work can begin.

LLB

At the core of BuildKit is a Low-Level Build (LLB) definition format. LLB is an intermediate binary format that allows developers to extend BuildKit. LLB defines a content-addressable dependency graph that can be used to put together very complex build definitions. It also supports features not exposed in Dockerfiles, like direct data mounting and nested invocation.

Directed acyclic graph (DAG)

Everything about execution and caching of your builds is defined in LLB. The caching model is entirely rewritten compared to the legacy builder. Rather than using heuristics to compare images, LLB directly tracks the checksums of build graphs and content mounted to specific operations. This makes it much faster, more precise, and portable. The build cache can even be exported to a registry, where it can be pulled on-demand by subsequent invocations on any host.

LLB can be generated directly using a golang client package that allows defining the relationships between your build operations using Go language primitives. This gives you full power to run anything you can imagine, but will probably not be how most people will define their builds. Instead, most users would use a frontend component, or LLB nested invocation, to run a prepared set of build steps.

Frontend

A frontend is a component that takes a human-readable build format and converts it to LLB so BuildKit can execute it. Frontends can be distributed as images, and the user can target a specific version of a frontend that is guaranteed to work for the features used by their definition.

For example, to build a Dockerfile with BuildKit, you would use an external Dockerfile frontend.

Getting started

BuildKit is enabled by default for all users on Docker Desktop. If you have installed Docker Desktop, you donât have to manually enable BuildKit. If you are running Docker on Linux, you can enable BuildKit either by using an environment variable or by making BuildKit the default setting.

To set the BuildKit environment variable when running the docker build command, run:

   $ DOCKER_BUILDKIT=1 docker build .

  

Note

Buildx always enables BuildKit.

To enable docker BuildKit by default, set daemon configuration in /etc/docker/daemon.json feature to true and restart the daemon. If the daemon.json file doesnât exist, create new file called daemon.json and then add the following to the file.

   {
  "features": {
    "buildkit" : true
  }
}

  

And restart the Docker daemon.

Warning

BuildKit only supports building Linux containers. Windows support is tracked in moby/buildkit#616

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BuildKit TOML configuration

The TOML file used to configure the buildkitd daemon settings has a short list of global settings followed by a series of sections for specific areas of daemon configuration.

The file path is /etc/buildkit/buildkitd.toml for rootful mode, ~/.config/buildkit/buildkitd.toml for rootless mode.

The following is a complete buildkitd.toml configuration example, please note some configuration is only good for edge cases, please take care of it carefully.

   debug = true
# root is where all buildkit state is stored.
root = "/var/lib/buildkit"
# insecure-entitlements allows insecure entitlements, disabled by default.
insecure-entitlements = [ "network.host", "security.insecure" ]

[grpc]
  address = [ "tcp://0.0.0.0:1234" ]
  # debugAddress is address for attaching go profiles and debuggers.
  debugAddress = "0.0.0.0:6060"
  uid = 0
  gid = 0
  [grpc.tls]
    cert = "/etc/buildkit/tls.crt"
    key = "/etc/buildkit/tls.key"
    ca = "/etc/buildkit/tlsca.crt"

# config for build history API that stores information about completed build commands
[history]
  # maxAge is the maximum age of history entries to keep, in seconds.
  maxAge = 172800
  # maxEntries is the maximum number of history entries to keep.
  maxEntries = 50

[worker.oci]
  enabled = true
  # platforms is manually configure platforms, detected automatically if unset.
  platforms = [ "linux/amd64", "linux/arm64" ]
  snapshotter = "auto" # overlayfs or native, default value is "auto".
  rootless = false # see docs/rootless.md for the details on rootless mode.
  # Whether run subprocesses in main pid namespace or not, this is useful for
  # running rootless buildkit inside a container.
  noProcessSandbox = false
  gc = true
  gckeepstorage = 9000
  # alternate OCI worker binary name(example 'crun'), by default either 
  # buildkit-runc or runc binary is used
  binary = ""
  # name of the apparmor profile that should be used to constrain build containers.
  # the profile should already be loaded (by a higher level system) before creating a worker.
  apparmor-profile = ""
  # limit the number of parallel build steps that can run at the same time
  max-parallelism = 4
  # maintain a pool of reusable CNI network namespaces to amortize the overhead
  # of allocating and releasing the namespaces
  cniPoolSize = 16

  [worker.oci.labels]
    "foo" = "bar"

  [[worker.oci.gcpolicy]]
    keepBytes = 512000000
    keepDuration = 172800
    filters = [ "type==source.local", "type==exec.cachemount", "type==source.git.checkout"]
  [[worker.oci.gcpolicy]]
    all = true
    keepBytes = 1024000000

[worker.containerd]
  address = "/run/containerd/containerd.sock"
  enabled = true
  platforms = [ "linux/amd64", "linux/arm64" ]
  namespace = "buildkit"
  gc = true
  # gckeepstorage sets storage limit for default gc profile, in MB.
  gckeepstorage = 9000
  # maintain a pool of reusable CNI network namespaces to amortize the overhead
  # of allocating and releasing the namespaces
  cniPoolSize = 16

  [worker.containerd.labels]
    "foo" = "bar"

  [[worker.containerd.gcpolicy]]
    keepBytes = 512000000
    keepDuration = 172800 # in seconds
    filters = [ "type==source.local", "type==exec.cachemount", "type==source.git.checkout"]
  [[worker.containerd.gcpolicy]]
    all = true
    keepBytes = 1024000000

# registry configures a new Docker register used for cache import or output.
[registry."docker.io"]
  # mirror configuration to handle path in case a mirror registry requires a /project path rather than just a host:port
  mirrors = ["yourmirror.local:5000", "core.harbor.domain/proxy.docker.io"]
  http = true
  insecure = true
  ca=["/etc/config/myca.pem"]
  [[registry."docker.io".keypair]]
    key="/etc/config/key.pem"
    cert="/etc/config/cert.pem"

# optionally mirror configuration can be done by defining it as a registry.
[registry."yourmirror.local:5000"]
  http = true

  

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