The worker needs quite a lot of configuration involving secrets. Baking them
in the AMI is just awful so we need to fetch them during the instance startup.
Previously, this was all done using cloud-init. This makes the cloud-init
config huge and it is also very hard to test.
This commit moves all the configuration scripts into the image itself.
Cloud-init still needs to be used to push the secret variables into the
instance. The configuration scripts are run after cloud-init. They pick up
yhe secrets and initialize the worker correctly.
These scripts were adopted from
75b752a1c0
(private repository).
During the adoption, some changes has to be applied to make shellcheck happy.
Signed-off-by: Ondřej Budai <ondrej@budai.cz>
