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This file contains hidden or bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters. Learn more about bidirectional Unicode charactersOriginal file line number Diff line number Diff line change @@ -0,0 +1,192 @@ # Dockerfile frontend experimental syntaxes ## Note for Docker users If you are using Docker v18.06 or later, BuildKit mode can be enabled by setting `export DOCKER_BUILDKIT=1` on the client side. Docker v18.06 also requires the daemon to be [running in experimental mode](https://docs.docker.com/engine/reference/commandline/dockerd/#description). You need to use `docker build` CLI instead of `buildctl` CLI mentioned in this document. See [the `docker build` document](https://docs.docker.com/engine/reference/commandline/build/) for the usage. ## Use experimental Dockerfile frontend The features mentioned in this document are experimentally available as [`docker/dockerfile:experimental`](https://hub.docker.com/r/docker/dockerfile/tags/) image. To use the experimental features, the first line of your Dockerfile needs to be `# syntax=docker/dockerfile:experimental`. As the experimental syntaxes may change in future revisions, you may want to pin the image to a specific revision. See also [#528](https://github.com/moby/buildkit/issues/528) for further information about planned `docker/dockerfile` releases. ## Experimental syntaxes ### `RUN --mount=type=bind` (the default mount type) This mount type allows binding directories (read-only) in the context or in an image to the build container. |Option |Description| |---------------------|-----------| |`target` (required) | Mount path.| |`source` | Source path in the `from`. Defaults to the root of the `from`.| |`from` | Build stage or image name for the root of the source. Defaults to the build context.| |`rw`,`readwrite` | Allow writes on the mount. Written data will be discarded.| ### `RUN --mount=type=cache` This mount type allows the build container to cache directories for compilers and package managers. |Option |Description| |---------------------|-----------| |`id` | Optional ID to identify separate/different caches| |`target` (required) | Mount path.| |`ro`,`readonly` | Read-only if set.| |`sharing` | One of `shared`, `private`, or `locked`. Defaults to `shared`. A `shared` cache mount can be used concurrently by multiple writers. `private` creates a new mount if there are multiple writers. `locked` pauses the second writer until the first one releases the mount.| |`from` | Build stage to use as a base of the cache mount. Defaults to empty directory.| |`source` | Subpath in the `from` to mount. Defaults to the root of the `from`.| |`mode` | File mode for new cache directory in octal. Default 0755.| |`uid` | User ID for new cache directory. Default 0.| |`gid` | Group ID for new cache directory. Default 0.| #### Example: cache Go packages ```dockerfile # syntax = docker/dockerfile:experimental FROM golang ... RUN --mount=type=cache,target=/root/.cache/go-build go build ... ``` #### Example: cache apt packages ```dockerfile # syntax = docker/dockerfile:experimental FROM ubuntu RUN rm -f /etc/apt/apt.conf.d/docker-clean; echo 'Binary::apt::APT::Keep-Downloaded-Packages "true";' > /etc/apt/apt.conf.d/keep-cache RUN --mount=type=cache,target=/var/cache/apt --mount=type=cache,target=/var/lib/apt \ apt update && apt-get --no-install-recommends install -y gcc ``` ### `RUN --mount=type=tmpfs` This mount type allows mounting tmpfs in the build container. |Option |Description| |---------------------|-----------| |`target` (required) | Mount path.| ### `RUN --mount=type=secret` This mount type allows the build container to access secure files such as private keys without baking them into the image. |Option |Description| |---------------------|-----------| |`id` | ID of the secret. Defaults to basename of the target path.| |`target` | Mount path. Defaults to `/run/secrets/` + `id`.| |`required` | If set to `true`, the instruction errors out when the secret is unavailable. Defaults to `false`.| |`mode` | File mode for secret file in octal. Default 0400.| |`uid` | User ID for secret file. Default 0.| |`gid` | Group ID for secret file. Default 0.| #### Example: access to S3 ```dockerfile # syntax = docker/dockerfile:experimental FROM python:3 RUN pip install awscli RUN --mount=type=secret,id=aws,target=/root/.aws/credentials aws s3 cp s3://... ... ``` ```console $ buildctl build --frontend=dockerfile.v0 --local context=. --local dockerfile=. \ --secret id=aws,src=$HOME/.aws/credentials ``` ### `RUN --mount=type=ssh` This mount type allows the build container to access SSH keys via SSH agents, with support for passphrases. |Option |Description| |---------------------|-----------| |`id` | ID of SSH agent socket or key. Defaults to "default".| |`target` | SSH agent socket path. Defaults to `/run/buildkit/ssh_agent.${N}`.| |`required` | If set to `true`, the instruction errors out when the key is unavailable. Defaults to `false`.| |`mode` | File mode for socket in octal. Default 0600.| |`uid` | User ID for socket. Default 0.| |`gid` | Group ID for socket. Default 0.| #### Example: access to Gitlab ```dockerfile # syntax = docker/dockerfile:experimental 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`. ``` ```console $ eval $(ssh-agent) $ ssh-add ~/.ssh/id_rsa (Input your passphrase here) $ buildctl build --frontend=dockerfile.v0 --local context=. --local dockerfile=. \ --ssh default=$SSH_AUTH_SOCK ``` You can also specify a path to `*.pem` file on the host directly instead of `$SSH_AUTH_SOCK`. However, pem files with passphrases are not supported. ### `RUN --security=insecure|sandbox` With `--security=insecure`, this runs the command without sandbox in insecure mode, which allows to run flows requiring elevated privileges (e.g. containerd). This is equivalent to running `docker run --privileged`. In order to access this feature, entitlement `security.insecure` should be enabled when starting the buildkitd daemon (`--allow-insecure-entitlement security.insecure`) and for a build request (`--allow security.insecure`). Default sandbox mode can be activated via `--security=sandbox`, but that is no-op. #### Example: check entitlements ```dockerfile # syntax = docker/dockerfile:experimental FROM ubuntu RUN --security=insecure cat /proc/self/status | grep CapEff ``` ``` #84 0.093 CapEff: 0000003fffffffff ``` ### `RUN --network=none|host|default` This allows control over which networking environment the command is run in. The allowed values are: * `none` - The command is run with no network access (`lo` is still available, but is isolated to this process) * `host` - The command is run in the host's network environment (similar to `docker build --network=host`, but on a per-instruction basis) * `default` - Equivalent to not supplying a flag at all, the command is run in the default network for the build The use of `--network=host` is protected by the `network.host` entitlement, which needs to be enabled when starting the buildkitd daemon (`--allow-insecure-entitlement network.host`) and on the build request (`--allow network.host`). #### Example: isolating external effects ```dockerfile # syntax = docker/dockerfile:experimental FROM python:3.6 ADD mypackage.tgz wheels/ RUN --network=none pip install --find-links wheels mypackage ``` `pip` will only be able to install the packages provided in the tarfile, which can be controlled by an earlier build stage.