Automate repository docs inclusion

[grobie]

So far every prometheus/alertmanater/... release branch had to be
manually configured in the nanoc.yaml config file. With this change the
most recent release branches will be checked out automatically if a
corresponding semver tag exists.

As the Prometheus git repository includes several hundreds of megabytes
of vendored assets, the repository is cloned bare and all blobs are
filtered by default. Each version is then checked out in an individual
working tree and git's spare-chekcout feature is used to reduce the
checkout to the docs/ folder. The git data is cached in
tmp/repo_docs/ and will be recreated automatically if removed.

Signed-off-by: Tobias Schmidt [email protected]

Fixes #1702.

[juliusv]

👍 Awesome, thanks! I didn't analyze every nanoc code bit in full detail, but the site seems to work great and the overall changes look and sound amazing as well. Yay for bare repos and sparse checkouts!

[grobie]

Note that the previous implementation already used sparse-checkouts. But git's new partialclonefilter = blob:none wasn't available back then, so I used depth=1 and individual checkouts. That doesn't work particularly well when also fetching tags/branches though. With the new approach only one git repo is necessary for all versions which should be dramatically faster on slower connections (not really relevant for netlify builds though obviously).

[juliusv]

👍 nice!

[roidelapluie]

Thanks!!!!!!