Fix support for existing plugin secret

[srpomeroy]

What does this PR change?

It provides the ability to reference a plugin secret managed outside of the helm chart by implementing a pattern we have used before.

Does this PR rely on any other PRs?

No

How does this PR impact users? (This is the kind of thing that goes in release notes!)

Fixes the ability to define an existing secret

Links to Issues or tickets this PR addresses or fixes

N/A

What risks are associated with merging this PR? What is required to fully test this PR?

Changes some of the helm values associated with plugins. Specifically, kubecostModel.plugins.configSecret is removed.

How was this PR tested?

Helm template against local copy of current develop branch

Have you made an update to documentation? If so, please provide the corresponding PR.

No. We do not cover custom secrets for plugins in our documentation. It is documented in the chart.

[srpomeroy]

How I am testing...

# Single Pod

## Customer Managed Secret
helm template ./cost-analyzer \
  --set=kubecostAggregator.deployMethod=singlepod \
  --set=prometheus.server.global.external_labels.cluster_id=some-cluster \
  --set=kubecostModel.plugins.enabled=true \
  --set=kubecostModel.plugins.existingCustomSecret.enabled=true \
  --set=kubecostModel.plugins.existingCustomSecret.name=custom-plugin-secret

## Kubecost Managed Secret
helm template ./cost-analyzer \
  --set=kubecostAggregator.deployMethod=singlepod \
  --set=prometheus.server.global.external_labels.cluster_id=some-cluster \
  --set=kubecostModel.plugins.enabled=true

# Stateful Set

## Customer Managed Secret
helm template ./cost-analyzer \
  --set=kubecostAggregator.deployMethod=statefulset \
  --set=kubecostModel.federatedStorageConfigSecret=some-secret \
  --set=prometheus.server.global.external_labels.cluster_id=some-cluster \
  --set=kubecostModel.plugins.enabled=true \
  --set=kubecostModel.plugins.existingCustomSecret.enabled=true \
  --set=kubecostModel.plugins.existingCustomSecret.name=custom-plugin-secret

## Kubecost Managed Secret
helm template ./cost-analyzer \
  --set=kubecostAggregator.deployMethod=statefulset \
  --set=kubecostModel.federatedStorageConfigSecret=some-secret \
  --set=prometheus.server.global.external_labels.cluster_id=some-cluster \
  --set=kubecostModel.plugins.enabled=true

[srpomeroy]

Using the above commands to test, here is the rendered manifest output for each.

Single Pod - Customer Managed Secret

---
# Source: cost-analyzer/templates/cost-analyzer-deployment-template.yaml
...
      volumes:
        - name: plugins-dir
          emptyDir: {}
        - name: plugins-config
          secret:
            secretName: custom-plugin-secret
            items:
              - key: datadog_config.json
                path: datadog_config.json
        - name: tmp
          emptyDir: {}
...

Single Pod - Kubecost Managed Secret

---
# Source: cost-analyzer/templates/plugins-config.yaml
apiVersion: v1
kind: Secret
metadata:
  name: kubecost-plugin-secret
  labels:
    app.kubernetes.io/name: cost-analyzer
    helm.sh/chart: cost-analyzer-2.2.2
    app.kubernetes.io/instance: release-name
    app.kubernetes.io/managed-by: Helm
    app: cost-analyzer
data: ...
---
# Source: cost-analyzer/templates/cost-analyzer-deployment-template.yaml
...
      volumes:
        - name: plugins-dir
          emptyDir: {}
        - name: plugins-config
          secret:
            secretName: kubecost-plugin-secret
            items:
              - key: datadog_config.json
                path: datadog_config.json
        - name: tmp
          emptyDir: {}
...

StatefulSet - Customer Managed Secret

---
# Source: cost-analyzer/templates/aggregator-cloud-cost-deployment.yaml
...
      volumes:
        - name: federated-storage-config
          secret:
            defaultMode: 420
            secretName: some-secret
        - name: persistent-configs
          emptyDir: {}
        - name: plugins-dir
          emptyDir: {}
        - name: plugins-config
          secret:
            secretName: custom-plugin-secret
            items:
              - key: datadog_config.json
                path: datadog_config.json
        - name: tmp
          emptyDir: {}
...
---
# Source: cost-analyzer/templates/cost-analyzer-deployment-template.yaml
...
      volumes:
        - name: plugins-dir
          emptyDir: {}
        - name: plugins-config
          secret:
            secretName: custom-plugin-secret
            items:
              - key: datadog_config.json
                path: datadog_config.json
        - name: tmp
          emptyDir: {}
...

StatefulSet - Kubecost Managed Secret

---
# Source: cost-analyzer/templates/plugins-config.yaml
apiVersion: v1
kind: Secret
metadata:
  name: kubecost-plugin-secret
  labels:
    app.kubernetes.io/name: cost-analyzer
    helm.sh/chart: cost-analyzer-2.2.2
    app.kubernetes.io/instance: release-name
    app.kubernetes.io/managed-by: Helm
    app: cost-analyzer
data:
---
# Source: cost-analyzer/templates/aggregator-cloud-cost-deployment.yaml
...
      volumes:
        - name: federated-storage-config
          secret:
            defaultMode: 420
            secretName: some-secret
        - name: persistent-configs
          emptyDir: {}
        - name: plugins-dir
          emptyDir: {}
        - name: plugins-config
          secret:
            secretName: kubecost-plugin-secret
            items:
              - key: datadog_config.json
                path: datadog_config.json
        - name: tmp
          emptyDir: {}
...
---
# Source: cost-analyzer/templates/cost-analyzer-deployment-template.yaml
...
      volumes:
        - name: plugins-dir
          emptyDir: {}
        - name: plugins-config
          secret:
            secretName: kubecost-plugin-secret
            items:
              - key: datadog_config.json
                path: datadog_config.json
        - name: tmp
          emptyDir: {}
...

[thomasvn]

Do you think we need to build any backwards compatibility here? Since we are changing value configSecret to secretName?

[thomasvn]

Nice addition, and very thorough testing. Thank you! Left one comment about backwards compatibility. Besides that, this LGTM!