ARM Deployment

Question 1

What is “dependsOn” in an ARM template?

Answer 1

dependsOn is a property you add to a resource in your template to tell Azure Resource Manager (ARM) that this resource must be deployed ONLY after some other resource(s) has fully finished deploying.

Sometimes you have resources that rely on others. For example:
A secret needs a Key Vault first
A VM needs storage or networking to be ready
A child resource depends on a parent resource

Without dependsOn, ARM might try deploying resources in parallel, which can break dependencies.

Question 2

What is a child resource in ARM templates?

Answer 2

A child resource is a resource that exists only within a parent resource and typically cannot exist independently. E.g. a vCPU is a child resource that only exists if inside a VM (parent resource).

Question 3

What is a template spec?

Answer 3

Template Spec is an Azure resource/container that stores a versioned ARM template (converted to JSON) in your subscription for reusability, version control, and access management across your organization. Each version of the template file is stored as a child resource inside the template spec with a unique deployable resource ID.

Question 4

Do you have to specify the version of a template spec to deploy?

Answer 4

You must specify the version number when deploying a template spec, so Azure Resource Manager knows which template file to use.

It’s a good practice to also give each version a version description summarising the changes that have been made/updated.