Filesets are named collections of files and directories that can be migrated between steps in the process of building a part. They are used within Craft Parts to collect and filter the files and directories a part needs in its stage and prime processing steps.

Tools that depend on Craft Parts can use filesets to simplify and automate migration of files and directories between build steps. Users of those tools may need to know about filesets if they need to adjust the contents of the packages that the tools produce.

Fileset names

Internally, Craft Parts uses the overlay, stage and prime filesets to migrate files from all parts into the corresponding steps. For example, the stage fileset refers to all the files and directories that will be moved into the staging area ready for the stage step to be run.

Defining filesets

Filesets are defined using the craft_parts.executor.Fileset class which is used to perform operations on lists of file paths. This accepts a string containing the name of the fileset and a list of strings containing the file paths.

Filesets are defined for individual parts. The scope of each fileset is the part it is defined in. Filesets defined in one part cannot be used by another part, and filesets cannot be shared between parts.

Specifying paths

The paths used in filesets specify locations relative to the working directory where they will be used. Absolute paths cannot be used.

Paths can specify single files or directories, such as these examples:

  • usr/bin/hello

  • usr/share

They can also contain wildcards to select multiple files and directories, such as these:

  • usr/bin/*

  • usr/lib/**/*.so*

The second of these examples selects all the shared libraries in all nested directories inside the usr/lib directory.

Filesets can also exclude files and directories. This is done by prefixing a path with the - character, as in these examples:

  • -usr/bin/hello

  • -usr/share/**/*.gz

The second example selects and discards gzipped files in all nested directories inside the usr/share directory.


If partitions are in use, bare path specifications (as demonstrated above) will refer to the default partition. The following two lines are equivalent:

  • usr/bin/hello

  • (default)/usr/bin/hello

Paths may be specified in any application-defined partition, like so:

  • (boot)/vmlinuz

  • (data)/static/uploads/example.png

Using filesets

Built-in filesets for the stage and prime steps are both applied to the directory containing the artefacts from the build step. These are used to specify the files and directories to migrate to the stage and prime steps.

The contents of the filesets for these steps are specified using the stage and prime properties when defining a part.

The order in which paths are defined in a fileset is not important. The paths are collected so that all files and directories to be included are first located, then paths that exclude files and directories are used to filter out those that are not needed.


When defined:

  • Filesets specify named collections of files and directories using file paths that can contain wildcards. Only relative paths are allowed.

  • They can both include and exclude sets of files and directories.

  • They are defined for a given part, not for multiple parts.

When used:

  • Filesets are used at the start of a step to collect and filter artefacts from an earlier step.

  • Their file paths are applied to the directory containing the artefacts from the earlier step.

  • All files and directories included by filesets are first located, then filtered by the filesets that exclude paths.