Programmatically Purge Frontdoor CDN

purge_frontdoor_cdn.yml

## Programmatically Purging Azure Frontdoor CDN With AzDevops

 1. Create a Azure Service Connection by creating a service principal so that devops process has access to perform pruging operation on frontdoor resource
    1. Create a App Registration -> as spn-devops-dev
    2. Goto Certificates and Secrets -> Add secret , note the ApplicationId and Secret
    3. Goto Frontdoor instance -> open Access Control (IAM) -> Add Role Assignment -> Role as "Contributor" -> Assign Access To-> "user, groups or service principal" -> Select -> search for service principal spn-devops-dev -> Select
    4. Note the Azure Service Connection name - as mymap-dev-service-connection
 2. Add environment variables for Azure FrontDoor, ResourceGroup and Service Connection
 3. Add a purging step which depends on the successly deploy. This ensure the cdn cache is refreshed with newer contents from the build after every build.

```yaml
 trigger:
  branches:
    include:
      - develop

pool: mymap-agent-pool-01

variables:
  - group: viz-variables-develop

schedules:
  - cron: "0 0 * * *"
    displayName: Daily midnight build - develop
    branches:
      include:
        - develop
    always: true

stages:
  - stage: package_build
    jobs:
      - template: azure-pipelines/templates/build-template.yml
        parameters:
          map_subscription_key: $(NEXT_PUBLIC_AZURE_MAP_SUBSCRIPTION_KEY)
          appinsights_instrumentation_key: $(NEXT_PUBLIC_APPINSIGHTS_INSTRUMENTATIONKEY)
          build_id: $(Build.BuildId)

  - stage: deploy
    dependsOn: package_build
    jobs:
      - template: azure-pipelines/templates/deploy-template.yml
        parameters:
          app_name: "mymap-dev"
          azure_service_connection: 'mymap-dev - Azure-PublishProfile'

  - stage: purge
    dependsOn: deploy
    jobs:
       - template: azure-pipelines/templates/purge-template.yml
         parameters:
           front_door: $(AZURE_FRONTDOOR)
           resource_group: $(AZURE_RESOURCE_GROUP)
           azure_service_connection: 'mymap-dev-service-connection'

```

purge-template.yml

```yaml
jobs:
- job: purge
  pool:
    vmImage: ubuntu-16.04
  steps:
  - task: AzureCLI@2
    inputs:
      azureSubscription: ${{ parameters.azure_service_connection }}
      scriptType: 'bash'
      scriptLocation: 'inlineScript'
      inlineScript: |
        az extension add --name front-door
        az network front-door purge-endpoint --resource-group ${{ parameters.resource_group}} --name ${{ parameters.front_door}} --content-paths "/"
```