Parts environment variables

When building a part to construct a snap, Snapcraft creates the following sets of environment variables that can optionally be used by a part’s build mechanism:

Environment variables can be accessed via the override- keywords with shell commands and Scriptlets, or more generally within your project’s build infrastructure.

See Adding parts for a general overview of what parts are and how to use them, and for more details on how parts are built within the snapcraft environment, including build stages and the directories they use, see Parts lifecycle.

For the various environment variables available to running snap applications, see Environment variables.

Locating directories

See Parts lifecycle and Parts directories for details on which directories are created and used when building a part.

core | core18 | core20

Snapcraft exposes the following directory related environment variables when building a part with bases core, core18, or core20. These can help when moving or locating files:

SNAPCRAFT_PART_SRC absolute path to where a part’s sources are pulled. It’s also the part’s working directory for the pull step
SNAPCRAFT_PART_BUILD absolute path to the sources used for the part’s build step. It is also the working directory of the build step.
SNAPCRAFT_PART_INSTALL absolute path to the results of the part’s build step. It also contains the staged packages of that part.
SNAPCRAFT_PRIME absolute path to where files are primed
SNAPCRAFT_PROJECT_DIR absolute path to the root of the snapcraft project
SNAPCRAFT_STAGE absolute path to where files are staged

core22

Snapcraft exposes the following directory related environment variables when build with base core22. These can help when moving or locating files:

CRAFT_PART_SRC
SNAPCRAFT_PART_SRC
absolute path to where a part’s sources are pulled. It’s also the part’s working directory for the pull step
CRAFT_PART_SRC_WORK
SNAPCRAFT_PART_SRC
absolute path to the part source subdirectory, if any. Defaults to the part source directory.
CRAFT_PART_BUILD
SNAPCRAFT_PART_BUILD
absolute path to the sources used for the part’s build step. It is also the working directory of the build step.
CRAFT_PART_BUILD_WORK
SNAPCRAFT_PART_BUILD_WORK
absolute path to the part build subdirectory in case of out-of-tree builds. Defaults to the part source directory.
CRAFT_PART_INSTALL
SNAPCRAFT_PART_INSTALL
absolute path to the results of the part’s build step. It also contains the staged packages of that part.
CRAFT_PRIME
SNAPCRAFT_PRIME
absolute path to where files are primed
CRAFT_PROJECT_DIR
SNAPCRAFT_PROJECT_DIR
absolute path to the root of the snapcraft project
CRAFT_STAGE
SNAPCRAFT_STAGE
absolute path to where files are staged
CRAFT_OVERLAY absolute path the part’s layer directory during the OVERLAY step if overlays are enabled.

Snapcraft configuration

core | core18 | core20

When building a part with bases core, core18, or core20, the following snapcraft environment variables are set:

SNAPCRAFT_ARCH_TRIPLET the architecture triplet used for the selected base
SNAPCRAFT_PARALLEL_BUILD_COUNT the preferred number of jobs the project is to be built with
SNAPCRAFT_PROJECT_NAME the snapcraft project name as set by name in snapcraft.yaml
SNAPCRAFT_PROJECT_VERSION the snapcraft project version as set by snapcraft.yaml
SNAPCRAFT_PROJECT_GRADE the snapcraft project grade as set in snapcraft.yaml
SNAPCRAFT_TARGET_ARCH deb-style architecture that snap is being built for, e.g. “amd64”, “armhf”, “arm64”, etc.

core22

When building a part with base core22, the following snapcraft environment variables are set:

CRAFT_ARCH_TRIPLET
SNAPCRAFT_ARCH_TRIPLET
the architecture triplet used for the selected base
CRAFT_PARALLEL_BUILD_COUNT
SNAPCRAFT_PARALLEL_BUILD_COUNT
the preferred number of jobs the project is to be built with
CRAFT_PROJECT_NAME
SNAPCRAFT_PROJECT_NAME
the snapcraft project name as set by name in snapcraft.yaml
CRAFT_TARGET_ARCH
SNAPCRAFT_TARGET_ARCH
deb-style architecture that snap is being built for, e.g. “amd64”, “armhf”, “arm64”, etc.
CRAFT_PART_NAME the part currently being processed, as set by the part’s name in snapcraft.yaml
CRAFT_STEP_NAME the step currently being executed (i.e. PRIME)

Build flags

The following specific build flags are also set:

CFLAGS empty unless after is used in the part and headers are staged in the common include paths for which they will be included (i.e.; paths added with -I)
CPPFLAGS same behavior as CFLAGS
CXXFLAGS same behavior as CFLAGS
LDFLAGS empty unless after is used in the part and headers are staged in the common library paths (i.e.; paths added with -L)
PKG_CONFIG_PATH empty unless after is used in the part and .pc files are staged in the common pkgconfig paths

Plugin variables

A part’s plugin can add its own set of environment variables, or expand on the above build related flags.

The build-environment keyword can be used to override or expand on the default environment variables. Here is a basic example:

parts:
  hello-part:
    source: gnu-hello.tar.gz
    plugin: autotools
    build-environment:
    - CFLAGS: "$CFLAGS -O3"  # add -O3 to the existing flags
    - LDFLAGS: "-L$SNAPCRAFT_STAGE/non-standard/lib"

The above example will override default flags and search for libraries in a non-standard path.

For a complete list of environment variables, see Environment variables exposed by Snapcraft.


Last updated a month ago.