@tashaemery I noticed that you approved this PR, but these tests are still failing. Are these false negatives?

@snh Thank you so much for your feedback and insight! I'm assuming adding zstd to the GitHub Enterprise server requires an internal PR? Let's say I change this PR to do the following:

1. Check if zstd is installed on the appliance. If so, use zstd for all manners of compression. Otherwise, default to gzip
2. Fix my logic around restoring old backup snapshots using gzip

Do you foresee any other reason for this PR not to land?

Thank you so much for your feedback and insight! I'm assuming adding zstd to the GitHub Enterprise server requires an internal PR? Let's say I change this PR to do the following:

@johnclaus That's correct, I've passed this PR on to the Engineering team responsible, who will be able to offer more insight as to our roadmap here.

Regarding backwards compatibility, an approach we have used in the past is to use the remote GitHub Enterprise Server version to determine when to use a new method/approach.

If you call ghe_remote_version_required in the relevant backup-utils scripts, then $GHE_REMOTE_VERSION, along with $GHE_VERSION_MAJOR, $GHE_VERSION_MINOR, and $GHE_VERSION_PATCH will be automatically populated.

For example, say zstd landed in GitHub Enterprise Server 2.25.0:

ghe_remote_version_required "$GHE_HOSTNAME"

if [ "$GHE_VERSION_MAJOR" -eq 2 ] && [ "$GHE_VERSION_MINOR" -ge 25 ] || [ "$GHE_VERSION_MAJOR" -ge 3 ]; then
  compress_command="zstd"
else
  compress_command="gzip"
fi

And then use $compress_command in place of gzip/zstd.

Something else that came to mind along the line of what @djdefi raised is that introducing zstd as a dependency on the backup-utils host may not be something we want to do in the short term due to the wide variety of systems out there running backup-utils. Some of these systems are in highly controlled environments where installing an additional package can be a challenge.

With this in mind, it might be worth limiting the initial implementation of zstd to those cases where it is ran on the GHES appliance.

This'd mean moving the routes list uses back to gzip.