add long term backup support with ghe-preserve

[cvega]

We have a couple of teams on services that are interested in preserving backups long term to meet specific compliance needs. To meet this need we created a ghe-preserve.

Looking to get feedback to see if something like this would be useful for inclusion.

What it does:

• create a date and hour range matching strategy
  • hourly snapshots for 48 hours
  • 14 days
  • 8 weeks (sunday)
  • 24 months
  • 5 years
• files matching the generated times/dates are copied to a 'preserve' folder assuming they do not already exist
• files in the preserve folder not matching hourly and dates are deleted
  • special care taken for edge cases (e.g. 48 hours can span 3 calendar days)

Other

• It never modifies an existing snapshot
• shellcheck mostly happy
• I did not update ghe-backup-config to include the preserve path, probably should
• I'm using arrays in a few places despite the style guide. I'd be interested in feedback and learning more in terms of avoiding this
• I didn't make it configurable because date time work coupled with deleting directories is honestly pretty scary and having a single state is easier.
• Not knowing a ton about how these snapshots work, is moving this data even viable for a restore assuming a user had to restore a snapshot from for example 18 months ago.

[gamefiend]

Hi @cvega! Apologies for the delay in response.

Before we go too deep, I want to check: Is this something you still need, or have your needs shifted?

[cvega]

Hello @gamefiend :wave:

We've provided this to a github customer who's been running it for awhile. I'm curious if this is something the team would be interested in and what it would take to incorporate.

[gamefiend]

If we still want to work on this, can you submit the change to the private repo? We can absolutely look at adding this feature and can open up a discussion for it. Will close this PR in the meantime.