No way to enable compression for backups via xtrabackup sidecar

[DimitriosLisenko]

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There doesn't seem to be a way to enable compression for backups when they are performed via the sidecar.

More about the problem

Attempted the following:

1. Set the following on the backup storage part of the PXC cluster:

      containerOptions:
        args:
          xbstream:
            - "--decompress"
          xtrabackup:
            - "--compress=zstd"

2. Set the following on the configuration part of the PXC cluster:

pxc:
  configuration: |
    [sst]
    xbstream-opts=--decompress
    [xtrabackup]
    compress=zstd

Neither options result in compressed backups.

Steps to reproduce

As above.

Versions

1. Kubernetes 1.35
2. Operator 1.19.0
3. Database 8.4.0

Anything else?

A quick look at the codebase suggests to me that the backup job is not setting the CONTAINER_OPTIONS environment variable that would have been used to set ContainerOptions on the BackupConfig?

Let me know if I'm missing something and there actually is a way to enable compression.

[egegunes]

@DimitriosLisenko You're right, this is a bug. I created K8SPXC-1796 to fix this in the next release.