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 | core24

Snapcraft exposes the following directory-related environment variables when building with bases core22 and core24. 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

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

SNAPCRAFT_ARCH_TRIPLET The deb-style architecture triplet specified by --target-arch. If a target arch is not provided, then the architecture of the build-on platform is used.
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 version in snapcraft.yaml
SNAPCRAFT_PROJECT_GRADE the snapcraft project grade as set in snapcraft.yaml
SNAPCRAFT_TARGET_ARCH the deb-style architecture that snap is being built for, e.g. “amd64”, “armhf”, “arm64”, etc.

core20

When building a part with base core20, the following snapcraft environment variables are set:

SNAPCRAFT_ARCH_BUILD_FOR the deb-style architecture of the platform the snap is built for.
SNAPCRAFT_ARCH_BUILD_ON the deb-style architecture of the platform the snap is built on.
SNAPCRAFT_ARCH_TRIPLET_BUILD_FOR the deb-style architecture triplet of the platform the snap is built for
SNAPCRAFT_ARCH_TRIPLET_BUILD_ON the deb-style architecture triplet of the platform the snap is built on
SNAPCRAFT_ARCH_TRIPLET The deb-style architecture triplet specified by --target-arch. If a target arch is not provided, then the architecture of the build-on platform is used.
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 version in snapcraft.yaml
SNAPCRAFT_PROJECT_GRADE the snapcraft project grade as set in snapcraft.yaml
SNAPCRAFT_TARGET_ARCH The deb-style architecture specified by --target-arch. If a target arch is not provided, then the architecture of the build-on platform is used.

core22

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

CRAFT_ARCH_BUILD_FOR the deb-style architecture of the platform the snap is built for

(available in snapcraft 8.0+)
CRAFT_ARCH_BUILD_ON the deb-style architecture of the platform the snap is built on

(available in snapcraft 8.0+)
CRAFT_ARCH_TRIPLET_BUILD_FOR the deb-style architecture triplet of the platform the snap is built for

(available in snapcraft 8.0+)
CRAFT_ARCH_TRIPLET_BUILD_ON the deb-style architecture triplet of the platform the snap is built on

(available in snapcraft 8.0+)
CRAFT_ARCH_TRIPLET
SNAPCRAFT_ARCH_TRIPLET
The deb-style architecture triplet specified by --target-arch. If a target arch is not provided, then the architecture of the build-on platform is used.

(deprecated in snapcraft 8.0, use CRAFT_ARCH_TRIPLET_BUILD_FOR instead)
CRAFT_TARGET_ARCH
SNAPCRAFT_TARGET_ARCH
The deb-style architecture specified by --target-arch. If a target arch is not provided, then the architecture of the build-on platform is used.

(deprecated in snapcraft 8.0, use CRAFT_ARCH_BUILD_FOR instead)
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
SNAPCRAFT_PROJECT_VERSION the snapcraft project version as set by snapcraft.yaml
SNAPCRAFT_PROJECT_GRADE the snapcraft project grade as set in snapcraft.yaml
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)

core24

When building a part with base core24, the following snapcraft environment variables are set:

CRAFT_ARCH_BUILD_FOR the deb-style architecture of the platform the snap is built for
CRAFT_ARCH_BUILD_ON the deb-style architecture of the platform the snap is built on
CRAFT_ARCH_TRIPLET_BUILD_FOR the deb-style architecture triplet of the platform the snap is built for
CRAFT_ARCH_TRIPLET_BUILD_ON the deb-style architecture triplet of the platform the snap is built on
CRAFT_PARALLEL_BUILD_COUNT
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
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 either override the default environment variables or define new ones. 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.

3 Likes

I propose to change

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

to

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

Thanks for the suggestion. I’ve updated the text match your words.

Hey Graham! I hope that you are doing well. Browsing through this documentation page, I have noticed that the core22 hyperlink in the Snapcraft configuration section of the table of contents is broken; if you click on it, nothing happens. It does not take you to the core22 section of Snapcraft configuration.

All the other hyperlinks in the table of contents seem to be working however. Probably just some small misconfiguration in the heading.

1 Like

Hello! Thanks so much for letting me know. This has now been fixed.

What would be the way to use secrets?

Let’s say you want users of your app has the credentials of their account as an ENV VAR, how should this work?

List should be properly indented, like this:

Very good point, thanks for taking the trouble to comment. This is fixed now. Thanks!

The language on this page is a little ambiguous. The only differentiator mentioned for what is supported and what isn’t is the base used. However, the version of snapcraft also matters. For instance, see snapcraft 7.x fails to replace new variables · Issue #4677 · canonical/snapcraft · GitHub

Instead, the particular version of SnapCraft which supports these variables should be mentioned. Perhaps a third column showing the range of versions supporting that variable?

@mr_cal for thoughts.

Thanks @dilyn, adding another column made the table crowded, hopefully the change I made is readable

1 Like

It’s workable. Thank you!

Hi! From a quick search I didn’t stumble upon a list of valid values for “deb-style architecture”. Would be nice to have a link.