What steps did you take and what happened:

When the Backup Hooks are configured to run on Sidecar Containers Velero complains about not being able to find the target container:

Errors:
  Velero:    message: /Error executing hook error: /no such container: "<container-name>"
             message: /Error executing hook error: /no such container: "<container-name>"

What did you expect to happen:
As Sidecar containers are a special case of InitContainers with RestartPolicy set to Always, it would be reasonable to have the option to configure Backup Hooks as commands to be executed on them.

The following information will help us better understand what's going on:

Anything else you would like to add:

Environment:

velero version
Client:
	Version: v1.17.0
	Git commit: -
Server:
	Version: 1.16.2

Vote on this issue!

This is an invitation to the Velero community to vote on issues, you can see the project's top voted issues listed here.
Use the "reaction smiley face" up to the right of this comment to vote.

• 👍 for "I would like to see this bug fixed as soon as possible"
• 👎 for "There are more important bugs to focus on right now"