Add support for defining pod and container overrides via attribute

[amisevsk]

What does this PR do?

This PR supercedes #868

Adds two new attributes:

• pod-overrides can be used to define overrides for the workspace pod
• container-overrides can be used to define overrides for individual workspace containers

The implementation of the override follows discussion in devfile/api#920. For pod-overrides, the attribute is used to override fields in a workspace deployment's podSpecTemplate in the same was as defined in #868. For container-overrides, the contents of the attribute are applied as a strategic merge patch on the container.

Container overrides can be specified to e.g. use extended Kubernetes resources:

components:
  - name: go
    attributes:
      container-overrides: {"resources":{"limits":{"nvidia.com/gpu":"1"}}}
    container:
      image: ...

For pod-overrides, since there are multiple places this attribute can be defined, all instances of the attribute are considered in the following order:

1. Any pod-overrides attributes in DevWorkspace components, in the order they appear
2. A pod-overrides attribute in the global attributes field .spec.template.attributes
   with later definitions overriding fields in previous ones. For example, the workspace

kind: DevWorkspace
apiVersion: workspace.devfile.io/v1alpha2
metadata:
  name: theia-next
spec:
  started: true
  template:
    attributes:
      pod-overrides:
        metadata:
          labels:
            shared-label: global-value
    components:
      - name: my-container-1
        attributes:
          pod-overrides:
            metadata:
              labels:
                shared-label: container1-value # Overridden by my-container-2 attribute, then global attribute
                container1-label: container1-value
                container2-label: container1-value # Overridden by my-container-2 attribute
        container:
          image: quay.io/wto/web-terminal-tooling:next
      - name: my-container-2
        attributes:
          pod-overrides:
            metadata:
              labels:
                shared-label: container2-value # Overridden by global attribute
                container2-label: container2-value
        container:
          image: quay.io/wto/web-terminal-tooling:next

will resolve to the overall override

metadata:
  labels:
    shared-label: global-value
    container1-label: container1-value
    container2-label: container2-value

Pod overrides can also be specified as json for compactness (without enclosing quotes):

kind: DevWorkspace
apiVersion: workspace.devfile.io/v1alpha2
metadata:
  name: sample
spec:
  started: true
  template:
    attributes:
      pod-overrides: {"spec":{"runtimeClassName":"kata"}}
# ...

What issues does this PR fix or reference?

Closes #852
Closes #945

Is it tested? How?

Test cases included in PR. Functionality can be tested using samples/pod-overrides.yaml and samples/container-overrides.yaml. For the pod overrides sample, the workspace will likely fail to stat as it sets the scheduler to stork and the runtimeClassName to kata, which are likely not available. To verify things are working as expected, check that fields are overridden in the Deployment for that workspace.

PR Checklist

• E2E tests pass (when PR is ready, comment /test v8-devworkspace-operator-e2e, v8-che-happy-path to trigger)
  • v8-devworkspace-operator-e2e: DevWorkspace e2e test
  • v8-che-happy-path: Happy path for verification integration with Che

[dkwon17]

The samples are working, tried different combinations of pod and container overrides, and the code looks good to me 👍

[AObuchow]

Code & test cases looks good to me. Tested on OpenShift and the workspace created by the pod-overrides.yaml sample had the correct fields overridden:

kind: Deployment
apiVersion: apps/v1
metadata:
  annotations:
    deployment.kubernetes.io/revision: '1'
  resourceVersion: '35882'
  name: workspacea0e5f894af174c4a
  uid: b2f001a4-7394-44bd-ba83-f537da406563
  creationTimestamp: '2022-10-05T17:06:14Z'
  generation: 2
(..)
  labels:
    controller.devfile.io/creator: ''
    controller.devfile.io/devworkspace_id: workspacea0e5f894af174c4a
    controller.devfile.io/devworkspace_name: theia-next
spec:
  replicas: 0
  selector:
    matchLabels:
      controller.devfile.io/devworkspace_id: workspacea0e5f894af174c4a
  template:
    metadata:
      name: workspacea0e5f894af174c4a
      namespace: devworkspace-controller
      creationTimestamp: null
      labels:
        controller.devfile.io/creator: ''
        controller.devfile.io/devworkspace_id: workspacea0e5f894af174c4a
        controller.devfile.io/devworkspace_name: theia-next
      annotations:
+        io.kubernetes.cri-o.userns-mode: 'auto:size=65536;map-to-root=true'
+        io.openshift.userns: 'true'
+        openshift.io/scc: container-build
    spec:
      restartPolicy: Always
(..)
      serviceAccountName: workspacea0e5f894af174c4a-sa
      imagePullSecrets:
        - name: workspacea0e5f894af174c4a-sa-dockercfg-4sw5t
+      schedulerName: stork
      terminationGracePeriodSeconds: 10
+      runtimeClassName: kata

[amisevsk]

/retest

[codecov]

Codecov Report

Base: 48.50% // Head: 49.16% // Increases project coverage by +0.65% 🎉

Coverage data is based on head (8985cf0) compared to base (96f534e).
Patch coverage: 68.60% of modified lines in pull request are covered.

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #944      +/-   ##
==========================================
+ Coverage   48.50%   49.16%   +0.65%     
==========================================
  Files          36       38       +2     
  Lines        2307     2390      +83     
==========================================
+ Hits         1119     1175      +56     
- Misses       1076     1093      +17     
- Partials      112      122      +10     

Impacted Files	Coverage Δ
pkg/library/container/container.go	48.38% <23.07%> (-23.05%)	⬇️
pkg/library/overrides/containers.go	67.85% <67.85%> (ø)
pkg/library/overrides/pods.go	82.22% <82.22%> (ø)

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[openshift-ci]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: amisevsk, AObuchow, dkwon17, ibuziuk

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