Flexible Metadata Format


The fmf Python module and command line tool implement a flexible format for defining metadata in plain text files which can be stored close to the source code and structured in a hierarchical way with support for inheritance.

Although the proposal initially originated from user stories centered around test execution, the format is general and thus can be used in broader scenarios, e.g. test coverage mapping.

Using this approach it’s also possible to combine both test execution metadata and test coverage information. Thanks to elasticity and hierarchy it provides ability to organize data into well-sized text documents while preventing duplication.


Command line usage is straightforward:

fmf command [options]

There are following commands available:

fmf ls      List identifiers of available objects
fmf show    Show metadata of available objects
fmf init    Initialize a new metadata tree
fmf clean   Remove cache directory and its content


List names of all objects stored in the metadata tree:

fmf ls

Show all test metadata (with ‘test’ attribute defined):

fmf show --key test

Show metadata for all tree nodes (not only leaves):

fmf show --key test --whole

List all attributes for the /recursion tests:

fmf show --key test --name /recursion

Show all covered requirements:

fmf show --key requirement --key coverage

Search for all tests with the Tier1 tag defined and show a brief summary of what was found:

fmf show --key test --filter tags:Tier1 --verbose

Use arbitrary Python expressions to access deeper objects and create more complex conditions:

fmf show --condition "execute['how'] == 'shell'"

Initialize a new metadata tree in the current directory:

fmf init

Check help message of individual commands for the full list of available options.


Here is the list of the most frequently used options.


Limit which metadata should be listed.


Key content definition (required attributes)


List objects with name matching regular expression


Apply advanced filter when selecting objects


Use arbitrary Python expression for filtering


Consider the whole tree (leaves only by default)

For filtering regular expressions can be used as well. See pydoc fmf.filter for advanced filtering options.


Choose the best format for showing the metadata.


Custom output format using the {} expansion


Values for the custom formatting string

See online documentation for details about custom format.


Various utility options.

--path PATHS

Path to the metadata tree (default: current directory)


Print additional information standard error output


Turn on debugging output, do not catch exceptions

Check help message of individual commands for the full list of available options.


The fmf package is available in Fedora and EPEL:

dnf install fmf

Install the latest version from the Copr repository:

dnf copr enable @teemtee/fmf
dnf install fmf

or use PIP:

pip install fmf

See documentation for more details about installation options.


Here is the list of environment variables understood by fmf:


Directory used to cache git clone calls for fmf identifiers.


Petr Šplíchal, Miro Hrončok, Jakub Krysl, Jan Ščotka, Alois Mahdal, Cleber Rosa, Miroslav Vadkerti, Lukáš Zachar, František Nečas, Evgeny Fedin, Pablo Martin, Zhaojuan Guo, Laura Barcziová, Petr Matyáš, Filip Vágner, Cristian Le and Ondrej Moriš.