Builtin args

Builtin args are variables with values automatically filled-in by Earthly.

The value of a builtin arg can never be overridden. However, you can always have an additional ARG, which takes as the default value, the value of the builtin arg. The additional arg can be overridden. Example

ARG EARTHLY_TARGET_TAG
ARG TAG=$EARTHLY_TARGET_TAG
SAVE IMAGE --push some/name:$TAG

Important

In contrast to Dockerfile predefined args, Earthly builtin args need to be pre-declared before they can be used. For example

ARG EARTHLY_TARGET
RUN echo "The current target is $EARTHLY_TARGET"

The following builtin args are available

Name	Description	Example value
EARTHLY_TARGET	The canonical reference of the current target.	For example, for a target named foo, which exists on john/work branch, in a repository at github.com/bar/buz, in a subdirectory src, the canonical reference would be github.com/bar/buz/src:john/work+foo. For more information about canonical references, see target referencing.
EARTHLY_TARGET_PROJECT	The project part of the canonical reference of the current target.	For the example above, the canonical project would be github.com/bar/buz/src:john
EARTHLY_TARGET_PROJECT_NO_TAG	The project part of the canonical reference of the current target, but without the tag.	For the example above, this would be github.com/bar/buz/src
EARTHLY_TARGET_NAME	The name part of the canonical reference of the current target.	For the example above, the name would be foo
EARTHLY_TARGET_TAG	The tag part of the canonical reference of the current target. Note that if the target has no canonical form, the value is an empty string.	For the example above, the tag would be john/work
EARTHLY_TARGET_TAG_DOCKER	The tag part of the canonical reference of the current target, sanitized for safe use as a docker tag. This is guaranteed to be a valid docker tag, even if no canonical form exists, in which case, latest is used.	For the example above, the docker tag would be john_work
EARTHLY_GIT_HASH	The git hash detected within the build context directory. If no git directory is detected, then the value is an empty string. Take care when using this arg, as the frequently changing git hash may be cause for not using the cache.	41cb5666ade67b29e42bef121144456d3977a67a
EARTHLY_GIT_SHORT_HASH	The first 8 characters of the git hash detected within the build context directory. If no git directory is detected, then the value is an empty string. Take care when using this arg, as the frequently changing git hash may be cause for not using the cache.	41cb5666
EARTHLY_GIT_ORIGIN_URL	The git URL detected within the build context directory. If no git directory is detected, then the value is an empty string. Please note that this may be inconsistent, depending on whether an HTTPS or SSH URL was used.	[e-mail]:bar/buz.git or https://github.com/bar/buz.git
EARTHLY_GIT_PROJECT_NAME	The git project name from within the git URL detected within the build context directory. If no git directory is detected, then the value is an empty string.	bar/buz
EARTHLY_GIT_COMMIT_TIMESTAMP	The committer timestamp, as unix seconds, of the git commit detected within the build context directory. If no git directory is detected, then the value is an empty string.	1626881847
EARTHLY_GIT_COMMIT_AUTHOR_TIMESTAMP	The author timestamp, as unix seconds, of the git commit detected within the build context directory. If no git directory is detected, then the value is an empty string.	1626881847
EARTHLY_VERSION *	The version of Earthly currently running.	v0.6.2
EARTHLY_BUILD_SHA *	The git hash of the commit which built the currently running version of Earthly.	1a9eda7a83af0e2ec122720e93ff6dbe9231fc0c
TARGETPLATFORM	The target platform the target is being built for.	linux/arm/v7, linux/amd64, linux/arm64
TARGETOS	The target OS the target is being built for.	linux
TARGETARCH	The target processor architecture the target is being built for.	arm, amd64, arm64
TARGETVARIANT	The target processor architecture variant the target is being built for.	v7
EARTHLY_SOURCE_DATE_EPOCH	The timestamp, as unix seconds, of the git commit detected within the build context directory. If no git directory is detected, then the value is 0 (the unix epoch)	1626881847, 0
USERPLATFORM	The platform the target is being built from.	linux/arm/v7, linux/amd64, darwin/arm64
USEROS	The OS the target is being built from.	linux, darwin
USERARCH	The processor architecture the target is being built from.	arm, amd64, arm64
USERVARIANT	The processor architecture variant the target is being built from.	v7

• requires use of feature-flag, for example: VERSION --earthly-version-arg 0.6.

Note

The classical Dockerfile predefined args are currently not available in Earthly.