Using build history

To enable build history, add the following to your conf/local.conf file:

INHERIT += "buildhistory"

The following enables information gathering, including dependency graphs:

BUILDHISTORY_COMMIT = "1"

The preceding line of code enables the storage of build history in a local Git repository.

The Git repository location can be set by the BUILDHISTORY_DIR variable, which by default is set to a buildhistory directory on your build directory.

By default, buildhistory tracks changes to packages, images, and SDKs. This is configurable using the BUILDHISTORY_FEATURES variable. For example, to track only image changes, add the following to your conf/local.conf:

BUILDHISTORY_FEATURES = "image"

It can also track specific files and copy them to the buildhistory directory. By default, this includes only /etc/passwd and /etc/groups, but it can be used to track any important files like security certificates. The files need to be added with the BUILDHISTORY_IMAGE_FILES variable in your conf/local.conf file as follows:

BUILDHISTORY_IMAGE_FILES += "/path/to/file"

Build history will slow down the build, increase the build size, and may also grow the Git directory to an unmanageable size. The recommendation is to enable it on a build server for software releases, or in specific cases, such as when updating production software.

When enabled, it will keep a record of the changes to each package and image in the form of a Git repository in a way that can be explored and analyzed.

For a package, it records the following information:

For an image, it records the following information:

And for an SDK, it records the following information:

To maintain the build history, it's important to optimize it and avoid it from growing over time. Periodic backups of the build history and clean-ups of older data are important to keep the build history repository at a manageable size.

Once the buildhistory directory has been backed up, the following process will trim it and keep only the most recent history: