Point In Time Recovery

[Zvirovyi]

Important!

This PR relies on the last version of charmed-mysql-snap and canonical/charmed-mysql-snap#62. Also, it's a copy of the VM PR.

Overview

MySQL stores binary transactions logs. This PR adds a service job to upload these logs to the S3 bucket and the ability to use them later for a point-in-time-recovery with a new restore-to-time parameter during restore. This new parameter accepts MySQL timestamp or keyword latest (for replaying all the transaction logs).

Also, a new application blocked status is introduced - Another cluster S3 repository to signal user that used S3 repository is claimed by the another cluster and binlogs collecting job is disabled and creating new backups is restricted (these are the only workload limitation). This is crucial to keep stored binary logs safe from the another clusters. This check uses @@GLOBAL.group_replication_group_name.
After restore, cluster group replication is reinitialized, so practically it becomes a new different cluster. For these cases, Another cluster S3 repository message is changed to the Move restored cluster to another S3 repository to indicate this event more conveniently for the user.
Both the block messages will disappear when S3 configuration is removed or changed to the empty repository.

Usage example

1. deploy mysql + s3-integrator and integrate them
2. create full backup
3. create test data:

create database zvirovyi;
use zvirovyi;
create table asd(message varchar(255) primary key);
select current_timestamp; # 2024-11-20 17:10:01
insert into asd values ('hello');
select current_timestamp; # 2024-11-20 17:10:12
insert into asd values ('world');
flush binary logs;

4. wait several minutes for binlogs to be uploaded
5. restore: juju run mysql/leader restore backup-id=2024-11-20T17:08:24Z restore-to-time="2024-11-20 17:10:01"

use zvirovyi;
select * from asd; # empty set returned

6. observe application block message
7. restore: juju run mysql/leader restore backup-id=2024-11-20T17:08:24Z restore-to-time="latest"

use zvirovyi;
select * from asd; # hello, world returned

Key notes

• binlogs collecting and PITR functionality depends on the https://github.com/canonical/mysql-pitr-helper

[Zvirovyi]

Tests are WIP!
UPD: integration tests done, and I will fix + add unit tests after PR review.

[paulomach]

You should use _get_cluster_member_addresses instead of creating a new method. It's tried and tested, and don't have the name resolution issue reported privately

[paulomach]

same as this

[paulomach]

Is there another way to configure the binlog collector so to avoid writting s3 secret-key to disk?

[sinclert-canonical]

👋🏻 Please remember to rebase your PR from main once all comments have been addressed.

LIBPATCH for this charm lib was bumped to 81 in this PR already.

[paulomach]

If the user always need to be super user, you can simplify _pitr_restore method to have the user in it, using the user and password attributes from the self object in MySQL class instance