docker buildx build [OPTIONS] PATH | URL | -
Start a build
docker build
, docker builder build
, docker image build
, docker buildx b
Name | Type | Default | Description |
---|---|---|---|
--add-host |
stringSlice |
Add a custom host-to-IP mapping (format: host:ip ) |
|
--allow |
stringSlice |
Allow extra privileged entitlement (e.g., network.host , security.insecure ) |
|
--annotation |
stringArray |
Add annotation to the image | |
--attest |
stringArray |
Attestation parameters (format: type=sbom,generator=image ) |
|
--build-arg |
stringArray |
Set build-time variables | |
--build-context |
stringArray |
Additional build contexts (e.g., name=path) | |
--builder |
string |
Override the configured builder instance | |
--cache-from |
stringArray |
External cache sources (e.g., user/app:cache , type=local,src=path/to/dir ) |
|
--cache-to |
stringArray |
Cache export destinations (e.g., user/app:cache , type=local,dest=path/to/dir ) |
|
--call |
string |
build |
Set method for evaluating build (check , outline , targets ) |
--cgroup-parent |
string |
Set the parent cgroup for the RUN instructions during build |
|
--check |
bool |
Shorthand for --call=check |
|
-D , --debug |
bool |
Enable debug logging | |
--detach |
bool |
Detach buildx server (supported only on linux) (EXPERIMENTAL) | |
-f , --file |
string |
Name of the Dockerfile (default: PATH/Dockerfile ) |
|
--iidfile |
string |
Write the image ID to a file | |
--label |
stringArray |
Set metadata for an image | |
--load |
bool |
Shorthand for --output=type=docker |
|
--metadata-file |
string |
Write build result metadata to a file | |
--network |
string |
default |
Set the networking mode for the RUN instructions during build |
--no-cache |
bool |
Do not use cache when building the image | |
--no-cache-filter |
stringArray |
Do not cache specified stages | |
-o , --output |
stringArray |
Output destination (format: type=local,dest=path ) |
|
--platform |
stringArray |
Set target platform for build | |
--progress |
string |
auto |
Set type of progress output (auto , plain , tty , rawjson ). Use plain to show container output |
--provenance |
string |
Shorthand for --attest=type=provenance |
|
--pull |
bool |
Always attempt to pull all referenced images | |
--push |
bool |
Shorthand for --output=type=registry |
|
-q , --quiet |
bool |
Suppress the build output and print image ID on success | |
--root |
string |
Specify root directory of server to connect (EXPERIMENTAL) | |
--sbom |
string |
Shorthand for --attest=type=sbom |
|
--secret |
stringArray |
Secret to expose to the build (format: id=mysecret[,src=/local/secret] ) |
|
--server-config |
string |
Specify buildx server config file (used only when launching new server) (EXPERIMENTAL) | |
--shm-size |
bytes |
0 |
Shared memory size for build containers |
--ssh |
stringArray |
SSH agent socket or keys to expose to the build (format: default|<id>[=<socket>|<key>[,<key>]] ) |
|
-t , --tag |
stringArray |
Name and optionally a tag (format: name:tag ) |
|
--target |
string |
Set the target build stage to build | |
--ulimit |
ulimit |
Ulimit options |
Flags marked with [experimental]
need to be explicitly enabled by setting the
BUILDX_EXPERIMENTAL=1
environment variable.
The docker buildx build
command starts a build using BuildKit.
You can add other hosts into a build container's /etc/hosts
file by using one
or more --add-host
flags. This example adds static addresses for hosts named
my-hostname
and my_hostname_v6
:
$ docker buildx build --add-host my_hostname=8.8.8.8 --add-host my_hostname_v6=2001:4860:4860::8888 .
If you need your build to connect to services running on the host, you can use
the special host-gateway
value for --add-host
. In the following example,
build containers resolve host.docker.internal
to the host's gateway IP.
$ docker buildx build --add-host host.docker.internal=host-gateway .
You can wrap an IPv6 address in square brackets.
=
and :
are both valid separators.
Both formats in the following example are valid:
$ docker buildx build --add-host my-hostname:10.180.0.1 --add-host my-hostname_v6=[2001:4860:4860::8888] .
--annotation="key=value"
--annotation="[type:]key=value"
Add OCI annotations to the image index, manifest, or descriptor.
The following example adds the foo=bar
annotation to the image manifests:
$ docker buildx build -t TAG --annotation "foo=bar" --push .
You can optionally add a type prefix to specify the level of the annotation. By
default, the image manifest is annotated. The following example adds the
foo=bar
annotation the image index instead of the manifests:
$ docker buildx build -t TAG --annotation "index:foo=bar" --push .
You can specify multiple types, separated by a comma (,) to add the annotation
to multiple image components. The following example adds the foo=bar
annotation to image index, descriptors, manifests:
$ docker buildx build -t TAG --annotation "index,manifest,manifest-descriptor:foo=bar" --push .
You can also specify a platform qualifier in square brackets ([os/arch]
) in
the type prefix, to apply the annotation to a subset of manifests with the
matching platform. The following example adds the foo=bar
annotation only to
the manifest with the linux/amd64
platform:
$ docker buildx build -t TAG --annotation "manifest[linux/amd64]:foo=bar" --push .
Wildcards are not supported in the platform qualifier; you can't specify a type
prefix like manifest[linux/*]
to add annotations only to manifests which has
linux
as the OS platform.
For more information about annotations, see Annotations.
--attest=type=sbom,...
--attest=type=provenance,...
Create image attestations. BuildKit currently supports:
-
sbom
- Software Bill of Materials.Use
--attest=type=sbom
to generate an SBOM for an image at build-time. Alternatively, you can use the--sbom
shorthand.For more information, see here.
-
provenance
- SLSA ProvenanceUse
--attest=type=provenance
to generate provenance for an image at build-time. Alternatively, you can use the--provenance
shorthand.By default, a minimal provenance attestation will be created for the build result, which will only be attached for images pushed to registries.
For more information, see here.
--allow=ENTITLEMENT
Allow extra privileged entitlement. List of entitlements:
network.host
- Allows executions with host networking.security.insecure
- Allows executions without sandbox. See related Dockerfile extensions.
For entitlements to be enabled, the BuildKit daemon also needs to allow them
with --allow-insecure-entitlement
(see create --buildkitd-flags
).
$ docker buildx create --use --name insecure-builder --buildkitd-flags '--allow-insecure-entitlement security.insecure'
$ docker buildx build --allow security.insecure .
You can use ENV
instructions in a Dockerfile to define variable values. These
values persist in the built image. Often persistence isn't what you want. Users
want to specify variables differently depending on which host they build an
image on.
A good example is http_proxy
or source versions for pulling intermediate
files. The ARG
instruction lets Dockerfile authors define values that users
can set at build-time using the --build-arg
flag:
$ docker buildx build --build-arg HTTP_PROXY=http://10.20.30.2:1234 --build-arg FTP_PROXY=http://40.50.60.5:4567 .
This flag allows you to pass the build-time variables that are
accessed like regular environment variables in the RUN
instruction of the
Dockerfile. These values don't persist in the intermediate or final images
like ENV
values do. You must add --build-arg
for each build argument.
Using this flag doesn't alter the output you see when the build process echoes theARG
lines from the
Dockerfile.
For detailed information on using ARG
and ENV
instructions, see the
Dockerfile reference.
You can also use the --build-arg
flag without a value, in which case the daemon
propagates the value from the local environment into the Docker container it's building:
$ export HTTP_PROXY=http://10.20.30.2:1234
$ docker buildx build --build-arg HTTP_PROXY .
This example is similar to how docker run -e
works. Refer to the docker run
documentation
for more information.
There are also useful built-in build arguments, such as:
BUILDKIT_CONTEXT_KEEP_GIT_DIR=<bool>
: trigger git context to keep the.git
directoryBUILDKIT_INLINE_CACHE=<bool>
: inline cache metadata to image config or notBUILDKIT_MULTI_PLATFORM=<bool>
: opt into deterministic output regardless of multi-platform output or not
$ docker buildx build --build-arg BUILDKIT_MULTI_PLATFORM=1 .
Learn more about the built-in build arguments in the Dockerfile reference docs.
--build-context=name=VALUE
Define additional build context with specified contents. In Dockerfile the context can be accessed when FROM name
or --from=name
is used.
When Dockerfile defines a stage with the same name it is overwritten.
The value can be a local source directory, local OCI layout compliant directory, container image (with docker-image:// prefix), Git or HTTP URL.
Replace alpine:latest
with a pinned one:
$ docker buildx build --build-context alpine=docker-image://alpine@sha256:0123456789 .
Expose a secondary local source directory:
$ docker buildx build --build-context project=path/to/project/source .
# docker buildx build --build-context project=https://github.com/myuser/project.git .
# syntax=docker/dockerfile:1
FROM alpine
COPY --from=project myfile /
Source an image from a local OCI layout compliant directory, either by tag, or by digest:
$ docker buildx build --build-context foo=oci-layout:///path/to/local/layout:<tag>
$ docker buildx build --build-context foo=oci-layout:///path/to/local/layout@sha256:<digest>
# syntax=docker/dockerfile:1
FROM alpine
RUN apk add git
COPY --from=foo myfile /
FROM foo
The OCI layout directory must be compliant with the OCI layout specification. You can reference an image in the layout using either tags, or the exact digest.
Same as buildx --builder
.
--cache-from=[NAME|type=TYPE[,KEY=VALUE]]
Use an external cache source for a build. Supported types are registry
,
local
, gha
and s3
.
registry
source can import cache from a cache manifest or (special) image configuration on the registry.local
source can import cache from local files previously exported with--cache-to
.gha
source can import cache from a previously exported cache with--cache-to
in your GitHub repositorys3
source can import cache from a previously exported cache with--cache-to
in your S3 bucket
If no type is specified, registry
exporter is used with a specified reference.
docker
driver currently only supports importing build cache from the registry.
$ docker buildx build --cache-from=user/app:cache .
$ docker buildx build --cache-from=user/app .
$ docker buildx build --cache-from=type=registry,ref=user/app .
$ docker buildx build --cache-from=type=local,src=path/to/cache .
$ docker buildx build --cache-from=type=gha .
$ docker buildx build --cache-from=type=s3,region=eu-west-1,bucket=mybucket .
More info about cache exporters and available attributes: https://github.com/moby/buildkit#export-cache
--call=[build|check|outline|targets]
BuildKit frontends can support alternative modes of executions for builds, using frontend methods. Frontend methods are a way to change or extend the behavior of a build invocation, which lets you, for example, inspect, validate, or generate alternative outputs from a build.
The --call
flag for docker buildx build
lets you specify the frontend
method that you want to execute. If this flag is unspecified, it defaults to
executing the build and evaluating build checks.
For Dockerfiles, the available methods are:
Command | Description |
---|---|
build (default) |
Execute the build and evaluate build checks for the current build target. |
check |
Evaluate build checks for the either the entire Dockerfile or the selected target, without executing a build. |
outline |
Show the build arguments that you can set for a target, and their default values. |
targets |
List all the build targets in the Dockerfile. |
subrequests.describe |
List all the frontend methods that the current frontend supports. |
Note that other frontends may implement these or other methods.
To see the list of available methods for the frontend you're using,
use --call=subrequests.describe
.
$ docker buildx build -q --call=subrequests.describe .
NAME VERSION DESCRIPTION
outline 1.0.0 List all parameters current build target supports
targets 1.0.0 List all targets current build supports
subrequests.describe 1.0.0 List available subrequest types
The --call=targets
and --call=outline
methods include descriptions for build targets and arguments, if available.
Descriptions are generated from comments in the Dockerfile. A comment on the
line before a FROM
instruction becomes the description of a build target, and
a comment before an ARG
instruction the description of a build argument. The
comment must lead with the name of the stage or argument, for example:
# syntax=docker/dockerfile:1
# GO_VERSION sets the Go version for the build
ARG GO_VERSION=1.22
# base-builder is the base stage for building the project
FROM golang:${GO_VERSION} AS base-builder
When you run docker buildx build --call=outline
, the output includes the
descriptions, as follows:
$ docker buildx build -q --call=outline .
TARGET: base-builder
DESCRIPTION: is the base stage for building the project
BUILD ARG VALUE DESCRIPTION
GO_VERSION 1.22 sets the Go version for the build
For more examples on how to write Dockerfile docstrings, check out the Dockerfile for Docker docs.
The check
method evaluates build checks without executing the build. The
--check
flag is a convenient shorthand for --call=check
. Use the check
method to validate the build configuration before starting the build.
$ docker buildx build -q --check https://github.com/docker/docs.git
WARNING: InvalidBaseImagePlatform
Base image wjdp/htmltest:v0.17.0 was pulled with platform "linux/amd64", expected "linux/arm64" for current build
Dockerfile:43
--------------------
41 | "#content/desktop/previous-versions/*.md"
42 |
43 | >>> FROM wjdp/htmltest:v${HTMLTEST_VERSION} AS test
44 | WORKDIR /test
45 | COPY --from=build /out ./public
--------------------
Using --check
without specifying a target evaluates the entire Dockerfile.
If you want to evaluate a specific target, use the --target
flag.
The outline
method prints the name of the specified target (or the default
target, if --target
isn't specified), and the build arguments that the target
consumes, along with their default values, if set.
The following example shows the default target release
and its build arguments:
$ docker buildx build -q --call=outline https://github.com/docker/docs.git
TARGET: release
DESCRIPTION: is an empty scratch image with only compiled assets
BUILD ARG VALUE DESCRIPTION
GO_VERSION 1.22 sets the Go version for the base stage
HUGO_VERSION 0.127.0
HUGO_ENV sets the hugo.Environment (production, development, preview)
DOCS_URL sets the base URL for the site
PAGEFIND_VERSION 1.1.0
This means that the release
target is configurable using these build arguments:
$ docker buildx build \
--build-arg GO_VERSION=1.22 \
--build-arg HUGO_VERSION=0.127.0 \
--build-arg HUGO_ENV=production \
--build-arg DOCS_URL=https://example.com \
--build-arg PAGEFIND_VERSION=1.1.0 \
--target release https://github.com/docker/docs.git
The targets
method lists all the build targets in the Dockerfile. These are
the stages that you can build using the --target
flag. It also indicates the
default target, which is the target that will be built when you don't specify a
target.
$ docker buildx build -q --call=targets https://github.com/docker/docs.git
TARGET DESCRIPTION
base is the base stage with build dependencies
node installs Node.js dependencies
hugo downloads and extracts the Hugo binary
build-base is the base stage for building the site
dev is for local development with Docker Compose
build creates production builds with Hugo
lint lints markdown files
test validates HTML output and checks for broken links
update-modules downloads and vendors Hugo modules
vendor is an empty stage with only vendored Hugo modules
build-upstream builds an upstream project with a replacement module
validate-upstream validates HTML output for upstream builds
unused-media checks for unused graphics and other media
pagefind installs the Pagefind runtime
index generates a Pagefind index
test-go-redirects checks that the /go/ redirects are valid
release (default) is an empty scratch image with only compiled assets
--cache-to=[NAME|type=TYPE[,KEY=VALUE]]
Export build cache to an external cache destination. Supported types are
registry
, local
, inline
, gha
and s3
.
registry
type exports build cache to a cache manifest in the registry.local
type exports cache to a local directory on the client.inline
type writes the cache metadata into the image configuration.gha
type exports cache through the GitHub Actions Cache service API.s3
type exports cache to a S3 bucket.
The docker
driver only supports cache exports using the inline
and local
cache backends.
Attribute key:
mode
- Specifies how many layers are exported with the cache.min
on only exports layers already in the final build stage,max
exports layers for all stages. Metadata is always exported for the whole build.
$ docker buildx build --cache-to=user/app:cache .
$ docker buildx build --cache-to=type=inline .
$ docker buildx build --cache-to=type=registry,ref=user/app .
$ docker buildx build --cache-to=type=local,dest=path/to/cache .
$ docker buildx build --cache-to=type=gha .
$ docker buildx build --cache-to=type=s3,region=eu-west-1,bucket=mybucket .
More info about cache exporters and available attributes: https://github.com/moby/buildkit#export-cache
When you run docker buildx build
with the --cgroup-parent
option,
the daemon runs the containers used in the build with the
corresponding docker run
flag.
$ docker buildx build -f <filepath> .
Specifies the filepath of the Dockerfile to use.
If unspecified, a file named Dockerfile
at the root of the build context is used by default.
To read a Dockerfile from stdin, you can use -
as the argument for --file
.
$ cat Dockerfile | docker buildx build -f - .
Shorthand for --output=type=docker
. Will automatically load the
single-platform build result to docker images
.
To output build metadata such as the image digest, pass the --metadata-file
flag.
The metadata will be written as a JSON object to the specified file. The
directory of the specified file must already exist and be writable.
$ docker buildx build --load --metadata-file metadata.json .
$ cat metadata.json
{
"buildx.build.provenance": {},
"buildx.build.ref": "mybuilder/mybuilder0/0fjb6ubs52xx3vygf6fgdl611",
"buildx.build.warnings": {},
"containerimage.config.digest": "sha256:2937f66a9722f7f4a2df583de2f8cb97fc9196059a410e7f00072fc918930e66",
"containerimage.descriptor": {
"annotations": {
"config.digest": "sha256:2937f66a9722f7f4a2df583de2f8cb97fc9196059a410e7f00072fc918930e66",
"org.opencontainers.image.created": "2022-02-08T21:28:03Z"
},
"digest": "sha256:19ffeab6f8bc9293ac2c3fdf94ebe28396254c993aea0b5a542cfb02e0883fa3",
"mediaType": "application/vnd.oci.image.manifest.v1+json",
"size": 506
},
"containerimage.digest": "sha256:19ffeab6f8bc9293ac2c3fdf94ebe28396254c993aea0b5a542cfb02e0883fa3"
}
Note
Build record provenance
(buildx.build.provenance
) includes minimal provenance by default. Set the
BUILDX_METADATA_PROVENANCE
environment variable to customize this behavior:
min
sets minimal provenance (default).max
sets full provenance.disabled
,false
or0
doesn't set any provenance.
Note
Build warnings (buildx.build.warnings
) are not included by default. Set the
BUILDX_METADATA_WARNINGS
environment variable to 1
or true
to
include them.
Available options for the networking mode are:
default
(default): Run in the default network.none
: Run with no network access.host
: Run in the host’s network environment.
Find more details in the Dockerfile reference.
The --no-cache-filter
lets you specify one or more stages of a multi-stage
Dockerfile for which build cache should be ignored. To specify multiple stages,
use a comma-separated syntax:
$ docker buildx build --no-cache-filter stage1,stage2,stage3 .
For example, the following Dockerfile contains four stages:
base
install
test
release
# syntax=docker/dockerfile:1
FROM oven/bun:1 as base
WORKDIR /app
FROM base AS install
WORKDIR /temp/dev
RUN --mount=type=bind,source=package.json,target=package.json \
--mount=type=bind,source=bun.lockb,target=bun.lockb \
bun install --frozen-lockfile
FROM base AS test
COPY --from=install /temp/dev/node_modules node_modules
COPY . .
RUN bun test
FROM base AS release
ENV NODE_ENV=production
COPY --from=install /temp/dev/node_modules node_modules
COPY . .
ENTRYPOINT ["bun", "run", "index.js"]
To ignore the cache for the install
stage:
$ docker buildx build --no-cache-filter install .
To ignore the cache the install
and release
stages:
$ docker buildx build --no-cache-filter install,release .
The arguments for the --no-cache-filter
flag must be names of stages.
-o, --output=[PATH,-,type=TYPE[,KEY=VALUE]
Sets the export action for the build result. The default output, when using the
docker
build driver, is a container
image exported to the local image store. The --output
flag makes this step
configurable allows export of results directly to the client's filesystem, an
OCI image tarball, a registry, and more.
Buildx with docker
driver only supports the local, tarball, and image
exporters. The docker-container
driver supports all exporters.
If you only specify a filepath as the argument to --output
, Buildx uses the
local exporter. If the value is -
, Buildx uses the tar
exporter and writes
the output to stdout.
$ docker buildx build -o . .
$ docker buildx build -o outdir .
$ docker buildx build -o - . > out.tar
$ docker buildx build -o type=docker .
$ docker buildx build -o type=docker,dest=- . > myimage.tar
$ docker buildx build -t tonistiigi/foo -o type=registry
You can export multiple outputs by repeating the flag.
Supported exported types are:
The local
export type writes all result files to a directory on the client. The
new files will be owned by the current user. On multi-platform builds, all results
will be put in subdirectories by their platform.
Attribute key:
dest
- destination directory where files will be written
For more information, see Local and tar exporters.
The tar
export type writes all result files as a single tarball on the client.
On multi-platform builds all results will be put in subdirectories by their platform.
Attribute key:
dest
- destination path where tarball will be written. “-” writes to stdout.
For more information, see Local and tar exporters.
The oci
export type writes the result image or manifest list as an OCI image
layout
tarball on the client.
Attribute key:
dest
- destination path where tarball will be written. “-” writes to stdout.
For more information, see OCI and Docker exporters.
The docker
export type writes the single-platform result image as a Docker image
specification
tarball on the client. Tarballs created by this exporter are also OCI compatible.
The default image store in Docker Engine doesn't support loading multi-platform
images. You can enable the containerd image store, or push multi-platform images
is to directly push to a registry, see registry
.
Attribute keys:
dest
- destination path where tarball will be written. If not specified, the tar will be loaded automatically to the local image store.context
- name for the Docker context where to import the result
For more information, see OCI and Docker exporters.
The image
exporter writes the build result as an image or a manifest list. When
using docker
driver the image will appear in docker images
. Optionally, image
can be automatically pushed to a registry by specifying attributes.
Attribute keys:
name
- name (references) for the new image.push
- Boolean to automatically push the image.
For more information, see Image and registry exporters.
The registry
exporter is a shortcut for type=image,push=true
.
For more information, see Image and registry exporters.
--platform=value[,value]
Set the target platform for the build. All FROM
commands inside the Dockerfile
without their own --platform
flag will pull base images for this platform and
this value will also be the platform of the resulting image.
The default value is the platform of the BuildKit daemon where the build runs.
The value takes the form of os/arch
or os/arch/variant
. For example,
linux/amd64
or linux/arm/v7
. Additionally, the --platform
flag also supports
a special local
value, which tells BuildKit to use the platform of the BuildKit
client that invokes the build.
When using docker-container
driver with buildx
, this flag can accept multiple
values as an input separated by a comma. With multiple values the result will be
built for all of the specified platforms and joined together into a single manifest
list.
If the Dockerfile
needs to invoke the RUN
command, the builder needs runtime
support for the specified platform. In a clean setup, you can only execute RUN
commands for your system architecture.
If your kernel supports binfmt_misc
launchers for secondary architectures, buildx will pick them up automatically.
Docker Desktop releases come with binfmt_misc
automatically configured for arm64
and arm
architectures. You can see what runtime platforms your current builder
instance supports by running docker buildx inspect --bootstrap
.
Inside a Dockerfile
, you can access the current platform value through
TARGETPLATFORM
build argument. Refer to the Dockerfile reference
for the full description of automatic platform argument variants .
You can find the formatting definition for the platform specifier in the containerd source code.
$ docker buildx build --platform=linux/arm64 .
$ docker buildx build --platform=linux/amd64,linux/arm64,linux/arm/v7 .
$ docker buildx build --platform=darwin .
--progress=VALUE
Set type of progress output (auto
, plain
, tty
, rawjson
). Use plain
to show container
output (default auto
).
Note
You can also use the BUILDKIT_PROGRESS
environment variable to set its value.
The following example uses plain
output during the build:
$ docker buildx build --load --progress=plain .
#1 [internal] load build definition from Dockerfile
#1 transferring dockerfile: 227B 0.0s done
#1 DONE 0.1s
#2 [internal] load .dockerignore
#2 transferring context: 129B 0.0s done
#2 DONE 0.0s
...
Note
Check also the BUILDKIT_COLORS
environment variable for modifying the colors of the terminal output.
The rawjson
output marshals the solve status events from BuildKit to JSON lines.
This mode is designed to be read by an external program.
Shorthand for --attest=type=provenance
, used to configure
provenance attestations for the build result. For example,
--provenance=mode=max
can be used as an abbreviation for
--attest=type=provenance,mode=max
.
Additionally, --provenance
can be used with Boolean values to enable or disable
provenance attestations. For example, --provenance=false
disables all provenance attestations,
while --provenance=true
enables all provenance attestations.
By default, a minimal provenance attestation will be created for the build result. Note that the default image store in Docker Engine doesn't support attestations. Provenance attestations only persist for images pushed directly to a registry if you use the default image store. Alternatively, you can switch to using the containerd image store.
For more information about provenance attestations, see here.
Shorthand for --output=type=registry
. Will automatically push the
build result to registry.
Shorthand for --attest=type=sbom
, used to configure SBOM
attestations for the build result. For example,
--sbom=generator=<user>/<generator-image>
can be used as an abbreviation for
--attest=type=sbom,generator=<user>/<generator-image>
.
Additionally, --sbom
can be used with Boolean values to enable or disable
SBOM attestations. For example, --sbom=false
disables all SBOM attestations.
Note that the default image store in Docker Engine doesn't support attestations. Provenance attestations only persist for images pushed directly to a registry if you use the default image store. Alternatively, you can switch to using the containerd image store.
For more information, see here.
--secret=[type=TYPE[,KEY=VALUE]
Exposes secrets (authentication credentials, tokens) to the build.
A secret can be mounted into the build using a RUN --mount=type=secret
mount in the
Dockerfile.
For more information about how to use build secrets, see
Build secrets.
Supported types are:
Buildx attempts to detect the type
automatically if unset.
Attribute keys:
id
- ID of the secret. Defaults to base name of thesrc
path.src
,source
- Secret filename.id
used if unset.
# syntax=docker/dockerfile:1
FROM python:3
RUN pip install awscli
RUN --mount=type=secret,id=aws,target=/root/.aws/credentials \
aws s3 cp s3://... ...
$ docker buildx build --secret id=aws,src=$HOME/.aws/credentials .
Attribute keys:
id
- ID of the secret. Defaults toenv
name.env
- Secret environment variable.id
used if unset, otherwise will look forsrc
,source
ifid
unset.
# syntax=docker/dockerfile:1
FROM node:alpine
RUN --mount=type=bind,target=. \
--mount=type=secret,id=SECRET_TOKEN,env=SECRET_TOKEN \
yarn run test
$ SECRET_TOKEN=token docker buildx build --secret id=SECRET_TOKEN .
Sets the size of the shared memory allocated for build containers when using
RUN
instructions.
The format is <number><unit>
. number
must be greater than 0
. Unit is
optional and can be b
(bytes), k
(kilobytes), m
(megabytes), or g
(gigabytes). If you omit the unit, the system uses bytes.
Note
In most cases, it is recommended to let the builder automatically determine the appropriate configurations. Manual adjustments should only be considered when specific performance tuning is required for complex build scenarios.
--ssh=default|<id>[=<socket>|<key>[,<key>]]
This can be useful when some commands in your Dockerfile need specific SSH authentication (e.g., cloning a private repository).
--ssh
exposes SSH agent socket or keys to the build and can be used with the
RUN --mount=type=ssh
mount.
Example to access Gitlab using an SSH agent socket:
# syntax=docker/dockerfile:1
FROM alpine
RUN apk add --no-cache openssh-client
RUN mkdir -p -m 0700 ~/.ssh && ssh-keyscan gitlab.com >> ~/.ssh/known_hosts
RUN --mount=type=ssh ssh -q -T git@gitlab.com 2>&1 | tee /hello
# "Welcome to GitLab, @GITLAB_USERNAME_ASSOCIATED_WITH_SSHKEY" should be printed here
# with the type of build progress is defined as `plain`.
$ eval $(ssh-agent)
$ ssh-add ~/.ssh/id_rsa
(Input your passphrase here)
$ docker buildx build --ssh default=$SSH_AUTH_SOCK .
$ docker buildx build -t docker/apache:2.0 .
This examples builds in the same way as the previous example, but it then tags the resulting
image. The repository name will be docker/apache
and the tag 2.0
.
You can apply multiple tags to an image. For example, you can apply the latest
tag to a newly built image and add another tag that references a specific
version.
For example, to tag an image both as docker/fedora-jboss:latest
and
docker/fedora-jboss:v2.1
, use the following:
$ docker buildx build -t docker/fedora-jboss:latest -t docker/fedora-jboss:v2.1 .
When building a Dockerfile with multiple build stages, use the --target
option to specify an intermediate build stage by name as a final stage for the
resulting image. The builder skips commands after the target stage.
FROM debian AS build-env
# ...
FROM alpine AS production-env
# ...
$ docker buildx build -t mybuildimage --target build-env .
--ulimit
overrides the default ulimits of build's containers when using RUN
instructions and are specified with a soft and hard limit as such:
<type>=<soft limit>[:<hard limit>]
, for example:
$ docker buildx build --ulimit nofile=1024:1024 .
Note
If you don't provide a hard limit
, the soft limit
is used
for both values. If no ulimits
are set, they're inherited from
the default ulimits
set on the daemon.
Note
In most cases, it is recommended to let the builder automatically determine the appropriate configurations. Manual adjustments should only be considered when specific performance tuning is required for complex build scenarios.