1.. SPDX-License-Identifier: CC-BY-SA-2.0-UK 2 3Creating a Software Bill of Materials 4************************************* 5 6Once you are able to build an image for your project, once the licenses for 7each software component are all identified (see 8":ref:`dev-manual/licenses:working with licenses`") and once vulnerability 9fixes are applied (see ":ref:`dev-manual/vulnerabilities:checking 10for vulnerabilities`"), the OpenEmbedded build system can generate 11a description of all the components you used, their licenses, their dependencies, 12their sources, the changes that were applied to them and the known 13vulnerabilities that were fixed. 14 15This description is generated in the form of a *Software Bill of Materials* 16(:term:`SBOM`), using the :term:`SPDX` standard. 17 18When you release software, this is the most standard way to provide information 19about the Software Supply Chain of your software image and SDK. The 20:term:`SBOM` tooling is often used to ensure open source license compliance by 21providing the license texts used in the product which legal departments and end 22users can read in standardized format. 23 24:term:`SBOM` information is also critical to performing vulnerability exposure 25assessments, as all the components used in the Software Supply Chain are listed. 26 27The OpenEmbedded build system doesn't generate such information by default. 28To make this happen, you must inherit the 29:ref:`ref-classes-create-spdx` class from a configuration file:: 30 31 INHERIT += "create-spdx" 32 33You then get :term:`SPDX` output in JSON format as an 34``IMAGE-MACHINE.spdx.json`` file in ``tmp/deploy/images/MACHINE/`` inside the 35:term:`Build Directory`. 36 37This is a toplevel file accompanied by an ``IMAGE-MACHINE.spdx.index.json`` 38containing an index of JSON :term:`SPDX` files for individual recipes, together 39with an ``IMAGE-MACHINE.spdx.tar.zst`` compressed archive containing all such 40files. 41 42The :ref:`ref-classes-create-spdx` class offers options to include 43more information in the output :term:`SPDX` data, such as making the generated 44files more human readable (:term:`SPDX_PRETTY`), adding compressed archives of 45the files in the generated target packages (:term:`SPDX_ARCHIVE_PACKAGED`), 46adding a description of the source files used to generate host tools and target 47packages (:term:`SPDX_INCLUDE_SOURCES`) and adding archives of these source 48files themselves (:term:`SPDX_ARCHIVE_SOURCES`). 49 50Though the toplevel :term:`SPDX` output is available in 51``tmp/deploy/images/MACHINE/`` inside the :term:`Build Directory`, ancillary 52generated files are available in ``tmp/deploy/spdx/MACHINE`` too, such as: 53 54- The individual :term:`SPDX` JSON files in the ``IMAGE-MACHINE.spdx.tar.zst`` 55 archive. 56 57- Compressed archives of the files in the generated target packages, 58 in ``packages/packagename.tar.zst`` (when :term:`SPDX_ARCHIVE_PACKAGED` 59 is set). 60 61- Compressed archives of the source files used to build the host tools 62 and the target packages in ``recipes/recipe-packagename.tar.zst`` 63 (when :term:`SPDX_ARCHIVE_SOURCES` is set). Those are needed to fulfill 64 "source code access" license requirements. 65 66See also the :term:`SPDX_CUSTOM_ANNOTATION_VARS` variable which allows 67to associate custom notes to a recipe. 68 69See the `tools page <https://spdx.dev/resources/tools/>`__ on the :term:`SPDX` 70project website for a list of tools to consume and transform the :term:`SPDX` 71data generated by the OpenEmbedded build system. 72 73See also Joshua Watt's 74`Automated SBoM generation with OpenEmbedded and the Yocto Project <https://youtu.be/Q5UQUM6zxVU>`__ 75presentation at FOSDEM 2023. 76