Controlling Deployment Order and Dependencies | Azure ARM Tutorial

Welcome to the tutorial on controlling deployment order and dependencies in ARM templates for Azure Resource Manager. When deploying resources in Azure, it's important to ensure that they are provisioned in the correct order to meet interdependencies and avoid deployment errors. ARM templates provide features that allow you to specify the deployment order and manage resource dependencies effectively.

1. Specifying Deployment Order

In ARM templates, you can specify the deployment order by controlling the sequence of resource definitions within the template. Resources listed earlier in the template will be provisioned first, followed by resources listed later.


"resources": [
  {
    "type": "Microsoft.Storage/storageAccounts",
    "name": "myStorageAccount",
    "apiVersion": "2021-04-01",
    ...
  },
  {
    "type": "Microsoft.Compute/virtualMachines",
    "name": "myVM",
    "apiVersion": "2021-03-01",
    ...
  }
]

2. Managing Resource Dependencies

To manage dependencies between resources, follow these steps:

Step 1: Identify Dependencies

Identify the dependencies between resources in your ARM template. Determine which resources need to be provisioned before others to ensure proper configuration and functionality.

Step 2: Define Dependencies

Specify the dependencies between resources using the dependsOn property within a resource's definition. The dependsOn property takes an array of resource names or resource IDs.


"resources": [
  {
    "type": "Microsoft.Compute/virtualMachines",
    "name": "myVM",
    "apiVersion": "2021-03-01",
    "dependsOn": [
      "Microsoft.Storage/storageAccounts/myStorageAccount"
    ],
    ...
  }
]

Step 3: Validate and Test

Validate your ARM template and test the deployment to ensure that the resources are provisioned in the desired order and that any interdependencies are properly managed. Validate that the resources are functioning as expected after the deployment.

Mistakes to Avoid

Not considering all the necessary dependencies and leaving out crucial resources.
Incorrect usage of the dependsOn property, resulting in unresolved dependencies.
Using incorrect resource names or IDs in the dependsOn property.

Frequently Asked Questions (FAQs)

Q: Can I specify dependencies across resource groups or subscriptions?
A: Yes, you can specify dependencies across resource groups and subscriptions by providing the fully qualified resource names or resource IDs in the dependsOn property.
Q: Can I have circular dependencies between resources in ARM templates?
A: No, circular dependencies are not supported in ARM templates. You need to ensure that your template dependencies do not create circular references.
Q: Can I conditionally control the deployment order?
A: No, the deployment order is determined by the sequence of resource definitions in the ARM template and cannot be conditionally controlled.
Q: Can I use expressions or functions to define dependencies?
A: No, dependencies in ARM templates are defined using the dependsOn property, and it does not support expressions or functions. Dependencies are based on the resource names or IDs.
Q: What happens if a resource's dependency is not yet provisioned?
A: ARM templates handle dependencies automatically by ensuring that resources are provisioned in the correct order. If a resource's dependency is not yet provisioned, the deployment will wait until the dependency is created.

Summary

In this tutorial, you learned how to control deployment order and manage dependencies in ARM templates for Azure Resource Manager. By specifying the deployment order and defining resource dependencies using the dependsOn property, you can ensure that resources are provisioned in the correct sequence and that any interdependencies are properly managed. By effectively managing deployment order and dependencies, you can create more organized and reliable deployments in Azure.