CTF Implementation

[fabianburth]

Description:
CTF Implementation

Done Criteria:

• ...
• Code has been reviewed by other team members
• Internal technical Documentation created/updated
• New / changed code is documented
• Analysis of existing tests (Unit and Integration)
• Unit Tests created for new code or existing Unit Tests updated
• Integration Test Suite updated (includes deletion of existing unnecessary Integration Test and/or creation of new ones if required)
• Enduser Documentation updated (if applicable)
• Successful demonstration in Review

[jakobmoellerdev]

There is an implementation for CTFs available here:
https://github.com/open-component-model/pocm/tree/main/bindings/golang/ctf

This implementation is the baseline for our prototyping.

I ran some appropriate rudimentary testing (that would allow a stability fit for a POC), but it needs more rigorous testing when trying to use for production.

Key features that I took over are:

1. Implementation of Permission Flag behavior
2. Transparent access of TGZ, TAR, and Directory format of CTFs
3. Free access on the artifact index

I combined this with an OCI Wrapper that maps OCI repository capabilities of ORAS to CTF. This is in the OCI module however since it only becomes relevant when interacting with the CTF as an OCI registry.

The main methods on the package are well documented and feedback has generally been received well.

[jakobmoellerdev]

One note here is that we also discovered the Artifact Set Archive format from old OCM. This format is not really needed in our opinion and we were able to achieve everything with an OCI Image Layout which is well defined. https://github.com/opencontainers/image-spec/blob/main/image-layout.md