Update site to use multistage build

[tbille]

Done

Update site to use multistage build Standardize our build process

QA

• DOCKER_BUILDKIT=1 docker build --build-arg BUILD_ID=test --tag maas-docs-multi .
• docker run -ti -p "8006:80" --env SECRET_KEY=secret_key maas-docs-multi
• http://0.0.0.0:8006/2.1/en/installconfig-images-mirror
• Make sure it works as usual

[carkod]

I'm getting this error when I try to build

#14 1.052   File "/usr/local/bin/documentation-builder", line 17, in <module>
#14 1.052     cli.main(sys.argv[1:])
#14 1.052   File "/usr/local/lib/python3.8/dist-packages/ubuntudesign/documentation_builder/cli.py", line 164, in main
#14 1.052     Builder(**arguments)
#14 1.052   File "/usr/local/lib/python3.8/dist-packages/ubuntudesign/documentation_builder/builder.py", line 112, in __init__
#14 1.052     version_branches = prepare_version_branches(
#14 1.052   File "/usr/local/lib/python3.8/dist-packages/ubuntudesign/documentation_builder/operations.py", line 228, in prepare_version_branches
#14 1.052     base_repo.create_head(name, ref.name)
#14 1.052   File "/usr/local/lib/python3.8/dist-packages/git/repo/base.py", line 366, in create_head
#14 1.052     return Head.create(self, path, commit, force, logmsg)
#14 1.052   File "/usr/local/lib/python3.8/dist-packages/git/refs/symbolic.py", line 546, in create
#14 1.052     return cls._create(repo, path, cls._resolve_ref_on_create, reference, force, logmsg)
#14 1.052   File "/usr/local/lib/python3.8/dist-packages/git/refs/symbolic.py", line 508, in _create
#14 1.052     raise OSError("Reference at %r does already exist, pointing to %r, requested was %r" %
#14 1.052 OSError: Reference at 'refs/heads/2.4' does already exist, pointing to 'dc9f4e22b6e95be12ccf92f8b6418c03219ada33', requested was '50e573e9a27633f84d14ef51b0fb6b1022de00d1'

[tbille]

I can't reproduce. Can you remove the local folder build and try again?

[jpmartinspt]

Just followed the QA steps without any issue.