[tyk-dashboard] Allow not setting certain postgres connection env vars

[dklenke]

Description

Adds helm value global.postgres.unsetConnectionEnvVars which allows user to not set any of the following environment variables

TYK_DB_STORAGE_MAIN_TYPE
TYK_DB_STORAGE_MAIN_CONNECTIONSTRING
TYK_DB_STORAGE_ANALYTICS_TYPE
TYK_DB_STORAGE_ANALYTICS_CONNECTIONSTRING
TYK_DB_STORAGE_UPTIME_TYPE
TYK_DB_STORAGE_UPTIME_CONNECTIONSTRING

Related Issue

Closes #403

Motivation and Context

As described in the issue using a postgres database with table sharding currently requires TYK_DB_STORAGE_ANALYTICS_TYPE to be unset.

Test Coverage For This Change

Screenshots (if appropriate)

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)
• Refactoring or add test (improvements in base code or adds test coverage to functionality)
• Documentation updates or improvements.

Checklist

• Make sure you are requesting to pull a topic/feature/bugfix branch (right side). If PRing from your fork, don't come from your master!
• Make sure you are making a pull request against our master branch (left side). Also, it would be best if you started your change off our latest master.
• My change requires a change to the documentation.
  • I have manually updated the README(s)/documentation accordingly.
• I have updated the documentation accordingly.
• I have added tests to cover my changes.
• All new and existing tests passed.

[dklenke]

I can add similar options to the other component charts to allow the umbrella chart to better use this setting if that is desired.

[dklenke]

Kustomize will have to do for now :)

helmCharts:
  - name: tyk-dashboard
    releaseName: tyk-dashboard
    version: 3.0.0
    repo: https://helm.tyk.io/public/helm/charts/
    valuesFile: values.yml

patches:
  - target:
      kind: Deployment
      name: dashboard-tyk-dashboard
    patch: |
      apiVersion: apps/v1
      kind: Deployment
      metadata:
        name: dashboard-tyk-dashboard
      spec:
        template:
          spec:
            containers:
            - name: dashboard-tyk-dashboard
              env:
                - name: TYK_DB_STORAGE_ANALYTICS_TYPE
                  $patch: delete