[FEATURE] Allow sourceDir to be inside data directory

[2ban]

Is your feature request related to a problem? Please describe.
When running restore with import we need to set sourceDir that is not inside data directory. This is difficult if cassandra is in kubernetes and it already has been mounted to volume. We cannot re-mount cassandra directory to subPath as this will require moving all cassandra data files one level down.

Describe the solution you'd like
A possibility to import restore data to directory inside cassandra data folder. Or any alternatives that could resolve this problem.

Describe alternatives you've considered
Re-mounting Cassandra to subPath, and another subPath dir for restore imports.
Attaching additional volume to cassandra - this will work but looks like overhead when we want to store backups on s3 but still need additional local storage.

Additional context
Condition that prevents from importing to dir inside of data dir.
(https://github.com/instaclustr/esop/blob/master/src/main/java/com/instaclustr/esop/impl/restore/RestoreOperationRequest.java#L358)

[smiklosovic]

Interesting. Thanks for reporting this. I should spend some time on this tool in a week or two. Stay tuned.

[2ban]

hi, @smiklosovic , any updates on this?

[smiklosovic]

@2ban could you give me the error you possibly get if you remove that condition here? Have you tried to do that without that if? Please do this on version you are running, do not take the code from master branch or similar. We need to be as close to what version you are running as possible and we will see how far we get. I think it is also important to test this on a node which is isolated from everything else (some testing node you can throw away) in case something goes wrong.

Also, don't you have some kind of a temporary directory in Kubernetes? /tmp? Why not to put it there? I do not know what Cassandra version you are running but if you use importing strategy instead of hardlinking, then after it is downloaded, it should be loaded via JMX to live Cassandra data dir path from /tmp (it does not need to be on the same block device as it has to be in case of hardlinking).

https://github.com/instaclustr/esop/blob/master/src/main/java/com/instaclustr/esop/impl/restore/RestoreOperationRequest.java#L358