:bug: create command always checks GitHub for last release, even when OCI is wanted

[jschoone]

/kind bug

What steps did you take and what happened: [A clear and concise description of what the bug is.]

git clone https://github.com/SovereignCloudStack/cluster-stacks
git clone https://github.com/SovereignCloudStack/csctl
cd csctl
make build
./csctl create ../cluster-stacks/providers/openstack/scs

Got error Error: failed to create create options: failed to create new github client: failed to create git config: environment variable GIT_PROVIDER is not set which is correct in general, but I only want to use an OCI registry

What did you expect to happen: When no GIT* env vars are set, the csctl tool could check if there are OCI env vars available instead to check for the latest stable version there. Alternatively or additionally and maybe even more stable could be a flag to set the target, since both GIT_ and OCI_* could be set.

Anything else you would like to add: [Miscellaneous information that will assist in solving the issue.]

Environment:

• csctl version: (use csctl version)
• OS (e.g. from /etc/os-release):

[jschoone]

In analysis with @DEiselt and @paulphys we found out it is more or less only necessary to change the github in https://github.com/SovereignCloudStack/csctl/blob/67ba98a679f2ee7b4b29d664f4484702ad511956/pkg/cmd/publish.go#L121 to oci. But then obviously github stops working. Generally we discussed those changes/additions needs to be implemented:

• [ ] deduplicate code in publish.go and create.go
• [x] add a flag to set the assetsclient, with options oci and github (github as default)
• [x] lookup specific env vars (OCI_ or GIT_) only when appropriate assetsclient is set
• [ ] add docs

[DEiselt]

Note: publish is not implemented for github clients. This needs to be checked and handled accordingly.