Unknown artifact media types should be handled more gracefully

[nkraetzschmar]

What happened:

Currently when a feature image script or builder wide image script outputs a new image artifact type the OCI upload in fails with

ValueError: Media type for {file_name} is not defined. You may want to add the definition to parse_features_lib

What you expected to happen:

Adding new outputs should not break OCI uploads. Ideally there would be a warning that some artifact types are not supported, but otherwise this error should be gracefully handled by still continuing with the upload for all other artifacts; i.e. lookup_media_type_for_file_name should be modified to return None instead of raising an exception if the artifact type is unknown.

Alternatively, if we want to enforce all artifacts have a media type mapping, then this mapping has to be moved into the features / builder scripts owning the corresponding image scripts. Having a split brain between the source of the image script and the python lib for something that is a hard required map causes needless maintenance headaches. One could for example extend the existing .artifacts file with a media type annotation¹.

How to reproduce it (as minimally and precisely as possible):

https://github.com/gardenlinux/gardenlinux/actions/runs/16668198895

Footnotes

1. This would require some spec version notation or similar in the artifacts file to maintain backwards compatibility, or some way to ensure old versions are not published with new python-gardenlinux-lib versions - contradictory to the direction proposed by https://github.com/gardenlinux/gardenlinux/pull/2955 ↩

[nkraetzschmar]

Personally I'd prefer the option of moving the media type annotation into the .artifacts file over simply ignoring unknown types, but that would require a more extensive re-write in the builder to support this.

[NotTheEvilOne]

For the current use case we would have three options:

• we could first apply feat: configure S3 upload metadata based on {cname}.requirements file #151 with the suggested media type for the time being

additionally:

• Completely ignore extensions with unknown mime types as they are not defined for either OCI or GL use cases
• Add an application/io.gardenlinux.extension.undefined.<original file extension> or application/x-io.gardenlinux.extension.<original file extension> fallback that is automatically applied in this case
• Move/add an mime type list that can be parsed by multiple tools to GL repository (JSON or YAML format) but this would require that for more use cases the repository (or the file) needs to be checked out before proceeding with the code logic