Optionally record additional information about `cosa buildupload s3` location + access to that location in meta.json

Feature Request

We wish to be able to upload the results of a successful RHCOS build into Brew. However, to avoid the huge penalty of uploading every (uncompressed!) artifact into Brew, we've reached an agreement with the Software Production folks that providing metadata about the build should suffice.

Since we treat S3 as our canonical source of truth (the bucket we use contains every production RHCOS build ever made), we want to be able to record this bucket in meta.json as a way for other processes that operate on Brew builds to know where the uploaded artifacts are located. Additionally, since the bucket is private and not accessible publicly, we want to provide information about the redirector service (https://rhcos-redirector.apps.art.xq1c.p1.openshiftapps.com/) so that it is possible for users to determine how to access the artifacts in the S3 bucket, by way of the redirector.

Desired Feature

The original design that I'm proposing here consists of two parts: an update to the meta.json schema and an enhancement to the cosa buildupload command.

The update to the meta.json schema would include a new optional s3 dict that would allow us to record the bucket name, subdirectory/path, and URL for the redirector service.

The enhancement to the cosa buildupload command would be some new option(s) that would allow the user to specify that information about the S3 bucket, path, and URL should be recorded in meta.json. Perhaps these options are only applicable to cosa buildupload s3.

Example Usage

Using the existing mechanism, this would instruct the command to split the bucket/path from the final argument and then record all the info to meta.json

$ cosa buildupload s3 --acl=private --record-s3-metadata --s3-url https://rhcos-redirector.apps.art.xq1c.p1.openshiftapps.com/art/storage/releases/rhcos-4.7-ppc64le art-rhcos-ci/releases/rhcos-4.7-ppc64le

Alternatively, change the invocation to support explicit options to specify bucket, path, url:

$ cosa buildupload s3 --acl=private --s3-url https://rhcos-redirector.apps.art.xq1c.p1.openshiftapps.com/art/storage/releases/rhcos-4.7-ppc64le --s3-bucket art-rhcos-ci --s3-path releases/rhcos-4.7-ppc64le

Other Information

This is in support of making RHCOS artifacts available to the various cloud marketplaces. See the AWS Marketplace Epic and the associated work stories attached to it https://issues.redhat.com/browse/COS-6

There is an outstanding PR that started on some of this request - https://github.com/coreos/coreos-assembler/pull/2731

Start with the cosa buildupload s3 entry point and the existing meta.json schema; review pull request #2731 for the work already attempted. Determine how the optional S3 bucket, path, and redirector URL should be represented and passed, then verify that successful S3 uploads record the metadata without changing existing uploads.