How to do it...

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

INHERIT += "buildhistory" 

The preceding configuration enables information gathering, including dependency graphs.

To enable the storage of build history in a local Git repository add the following line to the conf/local.conf configuration file as well:

BUILDHISTORY_COMMIT = "1"

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, such as 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.