use precreated labeled namespace for workspaces

[sparkoo]

Signed-off-by: Michal Vala mvala@redhat.com

What does this PR do?

Allow using precreated namespaces labeled with proper labels. The labels are configurable with che.infra.kubernetes.namespace.labels property.

Documentation PR

eclipse-che/che-docs#1643

TODO:

• Make labeled namespace as a valid namespace for creating new workspace (TODO in KubernetesNamespaceFactory.java)
• Javadocs
• Tests
• Documentation

Screenshot/screencast of this PR

What issues does this PR fix or reference?

#17842

How to test this PR?

1. create namespace with labels app.kubernetes.io/part-of=che.eclipse.org,app.kubernetes.io/component=workspace,che.eclipse.org/username=<username> and make sure your user has access to it (admin role)
2. On OpenShift with OAuth, it should be enough just to create RoleBinding for the user and admin role in pre-created project.
3. On Kubernetes, you will also need to add list namespaces clusterrole permission to che serviceaccount.
4. login to Che with the user
5. go to create new namespace page
6. you should see the namespace name in the dropdown "Namespace"
7. when you use factory to create a namespace, this labeled namespace will be used
8. when you label more namespaces, all will be shown in dashboard. If you use factory with more labeled namespaces, the first one will be used (should be alphabetical order, but not guaranteed)

PR Checklist

As the author of this Pull Request I made sure that:

• The Eclipse Contributor Agreement is valid
• Code produced is complete
• Code builds without errors
• Tests are covering the bugfix
• The repository devfile is up to date and works
• Sections What issues does this PR fix or reference and How to test this PR completed
• Relevant user documentation updated
• Relevant contributing documentation updated
• CI/CD changes implemented, documented and communicated

Reviewers

Reviewers, please comment how you tested the PR when approving it.

[sparkoo]

I've changed the labels property to use placeholders, because without them, we would not be able to be really flexible with label names.

[skabashnyuk]

looks 'ok' in general

[sparkoo]

@metlos @skabashnyuk @mshaposhnik ready to review