Support interpolated snapshot tags

[hanyuel]

Is this a bug fix or adding new feature?
New feature.

What is this PR about? / Why do we need it?
For more details, see issue #1553

1. Added support for interpolated snapshot tags that are dynamically computed at runtime using VolumeSnapshot name, namespace and VolumeSnapshotContent name.
2. Modified the helm chart template controller.yaml to allow setting --extra-create-metadata for csi-snapshotter sidecar. It enables external-snapshotter to pass the snapshot parameters to CSI Driver.
3. Added the documentation for Snapshot Tagging.

What testing is done?

1. Added unit tests of string interpolation on the VolumeSnapshot template.
2. E2E tests. Deployed the Driver with the changes. Provisioned a snapshot using this VolumeSnapshotClass

apiVersion: snapshot.storage.k8s.io/v1
kind: VolumeSnapshotClass
metadata:
  name: csi-aws-vsc
driver: ebs.csi.aws.com
deletionPolicy: Delete
parameters:
  tagSpecification_1: "key1={{ .VolumeSnapshotNamespace }}"
  tagSpecification_2: "key2={{ .VolumeSnapshotName }}"
  tagSpecification_3: "key3={{ .VolumeSnapshotContentName }}"
  tagSpecification_4: 'key4={{ .VolumeSnapshotName |  contains "ebs"}}'

and this VolumeSnapshot

apiVersion: snapshot.storage.k8s.io/v1
kind: VolumeSnapshot
metadata:
  name: ebs-volume-snapshot
spec:
  volumeSnapshotClassName: csi-aws-vsc
  source:
    persistentVolumeClaimName: ebs-claim

The tags for the snapshot in the AWS EC2 console were created as expected:

key2 | ebs-volume-snapshot
key1 | default
key3 | snapcontent-97516503-aa32-4fc5-96ae-3e694d2519d7
key4 | true

[k8s-ci-robot]

Hi @hanyuel. Thanks for your PR.

I'm waiting for a kubernetes-sigs member to verify that this patch is reasonable to test. If it is, they should reply with /ok-to-test on its own line. Until that is done, I will not automatically test new commits in this PR, but the usual testing commands by org members will still work. Regular contributors should join the org to skip this step.

Once the patch is verified, the new status will be reflected by the ok-to-test label.

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[ConnorJC3]

/ok-to-test

[torredil]

/retest

[torredil]

Waiting for #1560 to land, fixes pull-aws-ebs-csi-driver-test-helm-chart.

[torredil]

/lgtm

[torredil]

/hold will let the PR author unhold when everything is good to go.

[rdpsin]

/lgtm

[hanyuel]

/unhold

[gtxu]

Waiting for #1560 before we can merge this.

[torredil]

/retest

[ConnorJC3]

/retest

[ConnorJC3]

/retest
/lgtm

[rdpsin]

/lgtm

[torredil]

/lgtm

[k8s-ci-robot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: gtxu, torredil

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