Sunday, 14 November 2021

ADF Release - Update Linked Service while deploying

I'm deploying Azure Data Factory via DevOps pipelines through my DTAP environment. During the deployment I want to change the URL of the Linked Service from Azure Key Vault to point it to the Key Vault of that specific environment. How do I change that Linked Service in DevOps?
ADF Linked Service

This is possible by changing the ARM template parameter definition which on its turn will switch certain properties into overridable parameters during deployment. There is one downside: you cannot create a parameter for one specific Linked Service, because it will work for all Linked Services with that same property. However you can narrow it down to one particular type of Linked Service (for all Key Vaults in this example). 

1) Check Linked Service
For this example we will override the URL of the Azure Key Vault Linked Service, but first we need to find the actual property name that we want to override.
  • In ADF Studio go to Manage (toolbox icon in left menu) and then to Linked Services.
  • Now find your Key Vault Linked Service and hover your mouse over .it and click on the code icon {}.
  • Now check which property identifies a specific Key Vault. It should be within the typeProperties tag. In this case the baseUrl property contains a URL that points to one specific Key Vault.
baseURL property

Also notice the type property which will be used further on: AzureKeyVault

2) ARM template
Next step is to make this property overridable in the ARM template parameter definition (arm-template-parameters-definition.json). First the easiest way:
  • Under the same Manage menu item as step 1 go to ARM template
  • Click on Edit parameter configuration
  • Now find the baseUrl property within the Linked Services tag and change its value from "=" to "-" and then click on the OK button
Making baseUrl overridable

This will create a new parameter with the name: [LinkedServiceName]_properties_typeProperties_baseUrl

As mentioned before, this will now work for all Linked Services that have a (filled) property called baseUrl. A bit nicer is to instead create a Key Vault specific parameter by adding a piece JSON code below the general tag with the *. The name 'AzureKeyVault' from the code below can be found in the code of step 1.
        "AzureKeyVault": {
            "properties": {
                "typeProperties": {
                    "baseUrl": "-"

This will result in the same (long) parameter name, but now only for Linked Services pointing to Azure Key Vault. We can shorten that very long parameter name by adding -:-BaseUrl where the colon : is the separator for the next part of the property. This is the name of the parameter. Adding a minus - in front of that name will remove _properties_typeProperties from the parametername and shorten it to:
        "AzureKeyVault": {
            "properties": {
                "typeProperties": {
                    "baseUrl": "-:-BaseUrl"
This is much nicer. More info about this can be found in the documentation.

3) Adjust release pipeline
If you are using YAML to publish the changes then the only thing you have to change is the overrideParameters property by adding the new parameter ls_kv_bitools_baseUrl and adding either a variable or a hardcoded value. The > behind the property helps you to break the string over multiple lines and keep the YAML code more readable.
          # Deploy ADF Artifact
          - task: AzureResourceManagerTemplateDeployment@3
            displayName: '4 Deploy ADF Artifact'
              deploymentScope: 'Resource Group'
              azureResourceManagerConnection: 'sc_mcacc-adf-devopssp'
              subscriptionId: $(DataFactorySubscriptionId)
              action: 'Create Or Update Resource Group'
              resourceGroupName: $(DataFactoryResourceGroupName)
              location: 'West Europe'
              templateLocation: 'Linked artifact'
              csmFile: '$(Pipeline.Workspace)/ArmTemplatesArtifact/ARMTemplateForFactory.json'
              csmParametersFile: '$(Pipeline.Workspace)/ArmTemplatesArtifact/ARMTemplateParametersForFactory.json'
              overrideParameters: > 
                -factoryName $(DataFactoryName) 
                -ls_kv_bitools_baseUrl ""
              deploymentMode: 'Incremental'

                SYSTEM_ACCESSTOKEN: $(System.AccessToken)
If you are not sure about which parameternames you can use in the YAML, then you can lookup that name by exporting the ARM template under ARM template. Then check arm_template.json or arm_template_parameters.json
export template to find parametername

And if you're using the Release pipelines with the ARM template deployment task then you can just go to the Override template parameters property, click on the edit button and replace the value with a new value or a variable from a variable group.
ARM template deployment - Override template parameters

In this post you learned how to override properties of a Linked Service during deployment via Azure DevOps. This allows you to point your Linked Service to the correct service for that specific environment. The most likely candidate for this is probably the Linked Service pointing to Azure Key Vault where you store all other connection details.

In a previous post we also showed you how to change Global Parameters during deployment and in a next post we will show you how to change triggers during deployment because you probably don't want to use the same triggers on development, test, acceptance and production.

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