(plain bundle usage) Documentation on how to add a plain bundle image to a file-based catalog

[rashmigottipati]

Description of the change:
Write a plain bundle usage document by listing the process required to build a plain bundle image and add it to a file-based catalog.

Motivation for the change:
The goal of this document is to highlight steps to add a plain bundle image to a file-based catalog and enumerate the experimental olm.bundle.mediatype field. Currently,opm does not support plain bundles i.e. plain bundles cannot be rendered through opm render as the plain+v0 format is just the manifests and opm render would require the manifests and metadata in order to be able to render the plain bundle. This documentation provides instructions on how to manually include the plain bundle in a file-based catalog. Please note that this is experimental for now and not recommended for production usage.

Reviewer Checklist

• Implementation matches the proposed design, or proposal is updated to match implementation
• Sufficient unit test coverage
• Sufficient end-to-end test coverage
• Docs updated or added to /docs
• Commit messages sensible and descriptive

Doc collaboration with @michaelryanpeter

[codecov]

Codecov Report

Merging #1127 (2b4c7a8) into master (fa1b456) will decrease coverage by 0.01%.
Report is 1 commits behind head on master.
The diff coverage is n/a.

@@            Coverage Diff             @@
##           master    #1127      +/-   ##
==========================================
- Coverage   53.78%   53.77%   -0.01%     
==========================================
  Files         108      108              
  Lines       10163    10163              
==========================================
- Hits         5466     5465       -1     
- Misses       3736     3738       +2     
+ Partials      961      960       -1     

see 1 file with indirect coverage changes

[everettraven]

Overall looks great! There are a few minor changes that need to be made. I've also left a few styling nits:

[joelanford]

Is this flag required on the opm init command? If not, I'd suggest removing it because default channel is not an OLMv1 concept.

If it is required, should we consider an alternate instruction that has the user use HEREDOC to cat an olm.package directly into a file?

My motivation here is to avoid leaking OLMv0-specific APIs/concepts/behaviors into OLMv1 stuff.

[rashmigottipati]

That makes sense. So, the flag itself is not required and I've removed it from the command. However, without the flag too, opm init generates an empty default channel in the index "defaultChannel": "".

I am guessing we should remove this line manually from the index. I think it should be ok for this doc to use the opm init and then explicitly mention about removing the empty default channel from the index file. Open to knowing about any other alternatives.

[michaelryanpeter]

Most of these comments address consistency usage. There are a couple of places where the instructions as written did not work for me, and I had to do something different. It could be because I used the Helm memcached-operator. But I am happy to sync to figure out what we need to change.

[michaelryanpeter]

I left a few nits. Otherwise, LGTM!

[michaelryanpeter]

/lgtm

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[everettraven]

/lgtm

[oceanc80]

/approve

[openshift-ci]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: everettraven, michaelryanpeter, oceanc80, rashmigottipati

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