ARM template resources section in Azure - Step-by-Step Execution

Process Flow - ARM template resources section

Start ARM Template

↓

Parse 'resources' array

↓

For each resource in array

↓

Validate resource properties

↓

Deploy resource

↓

Repeat for next resource

↓

End deployment

The ARM template processes the 'resources' array one by one, validating and deploying each resource in order.

Execution Sample

Azure

{
  "resources": [
    {
      "type": "Microsoft.Storage/storageAccounts",
      "name": "mystorageaccount",
      "apiVersion": "2022-09-01",
      "location": "eastus",
      "sku": {
        "name": "Standard_LRS"
      },
      "kind": "StorageV2",
      "properties": {}
    }
  ]
}

This snippet defines a storage account resource to be deployed in the 'resources' section of an ARM template.

Process Table

Step	Action	Resource Name	Resource Type	Validation Result	Deployment Status
1	Parse 'resources' array	-	-	-	-
2	Select first resource	mystorageaccount	Microsoft.Storage/storageAccounts	-	-
3	Validate resource properties	mystorageaccount	Microsoft.Storage/storageAccounts	Valid	-
4	Deploy resource	mystorageaccount	Microsoft.Storage/storageAccounts	Valid	Deployed
5	No more resources	-	-	-	Deployment complete

💡 All resources processed and deployed successfully.

Status Tracker

Variable	Start	After Step 2	After Step 3	After Step 4	Final
resources	[{storageAccount}]	[{storageAccount}]	[{storageAccount}]	[{storageAccount}]	[{storageAccount}]
currentResource	null	{storageAccount}	{storageAccount}	null	null
validationStatus	null	null	Valid	Valid	Valid
deploymentStatus	null	null	null	Deployed	Deployed

Key Moments - 2 Insights

Why does the deploymentStatus change only after validation?

Because the ARM template must first confirm the resource properties are valid before deploying, as shown in steps 3 and 4 of the execution_table.

What happens if there are multiple resources in the 'resources' array?

The template processes each resource one by one in order, repeating steps 2 to 4 for each resource until all are deployed, as indicated by the loop in the concept_flow.

Visual Quiz - 3 Questions

Look at the execution_table, what is the validationStatus at Step 3?

A null

B Valid

C Invalid

D Deployed

💡 Hint

Check the 'validationStatus' column at Step 3 in the execution_table.

At which step does the resource deployment happen?

A Step 4

B Step 2

C Step 3

D Step 5

💡 Hint

Look for 'Deploy resource' action in the execution_table.

If a second resource was added, how would the execution_table change?

A Validation would be skipped for the second resource.

B Deployment would stop after the first resource.

C Steps 2 to 4 would repeat for the second resource before Step 5.

D Step 5 would occur before deploying the second resource.

💡 Hint

Refer to the concept_flow showing the loop over each resource.

Concept Snapshot

ARM template 'resources' section:
- Contains an array of resource objects.
- Each resource has 'type', 'name', 'apiVersion', 'location', and 'properties'.
- ARM processes each resource sequentially: validate then deploy.
- Deployment stops only after all resources are processed.
- Proper validation ensures successful deployment.

Full Transcript

The ARM template's resources section is an array listing all resources to deploy. The deployment engine reads this array, picks each resource, checks its properties for correctness, and then deploys it. This process repeats until all resources are deployed. The execution table shows these steps clearly: parsing the array, selecting a resource, validating it, deploying it, and then finishing when no resources remain. Variables like currentResource, validationStatus, and deploymentStatus track progress. Understanding this flow helps beginners see how ARM templates manage infrastructure deployment step-by-step.

Practice

1. What is the main purpose of the resources section in an ARM template?

easy

A. To list all cloud parts to create or update

B. To write scripts for manual deployment

C. To store user credentials securely

D. To monitor cloud resource usage

Solution

1. Step 1: Understand the role of the resources section

   The resources section defines what cloud parts (like servers, databases) to create or update automatically.

2. Step 2: Compare options with this role

   Only To list all cloud parts to create or update correctly describes this purpose. Other options describe unrelated tasks.

3. Final Answer:

   To list all cloud parts to create or update -> Option A

4. Quick Check:

   Resources section = list cloud parts [OK]

Hint: Resources section always defines cloud parts to deploy [OK]

Common Mistakes:

• Thinking resources section stores credentials
• Confusing resources with monitoring tools
• Assuming resources section is for scripts

2. Which of the following is a required property inside each resource in the resources section of an ARM template?

easy

A. version

B. dependsOn

C. location

D. tags

Solution

1. Step 1: Identify required properties for each resource

   Every Azure resource requires type, apiVersion, and name. The location property is required for regional resources to specify where the resource is created.

2. Step 2: Check options for required property

   location (location) is required. version is incorrect; the correct property is apiVersion. tags and dependsOn are optional.

3. Final Answer:

   location -> Option C

4. Quick Check:

   Location is required for resource placement [OK]

Hint: Location is required for regional resources [OK]

Common Mistakes:

• Confusing apiVersion with version
• Assuming tags are mandatory
• Thinking dependsOn is always required

3. Given this resource snippet in an ARM template's resources section:

{
  "type": "Microsoft.Storage/storageAccounts",
  "apiVersion": "2022-09-01",
  "name": "mystorageaccount",
  "location": "eastus",
  "sku": { "name": "Standard_LRS" },
  "kind": "StorageV2"
}

What will happen when this template is deployed?

medium

A. Deployment fails due to missing 'dependsOn' property

B. A new storage account named 'mystorageaccount' is created in East US

C. The storage account is created but with default SKU

D. The template will error because 'kind' is invalid

Solution

1. Step 1: Analyze resource properties

   The resource defines a storage account with a valid type, apiVersion, name, location, sku, and kind. All required fields are present and valid.

2. Step 2: Understand deployment behavior

   Since all required properties are correct, deployment will create the storage account named 'mystorageaccount' in 'eastus' with the specified SKU and kind. dependsOn is optional here.

3. Final Answer:

   A new storage account named 'mystorageaccount' is created in East US -> Option B

4. Quick Check:

   Valid resource properties = successful creation [OK]

Hint: Check required fields; missing dependsOn is okay if no dependencies [OK]

Common Mistakes:

• Thinking dependsOn is always mandatory
• Assuming default SKU applies if specified
• Believing 'kind' property is invalid

4. You have this resource in your ARM template's resources section:

{
  "type": "Microsoft.Web/sites",
  "apiVersion": "2021-02-01",
  "name": "mywebapp",
  "location": "westus"
}

Deployment fails with an error about missing properties. What is the likely cause?

medium

A. Missing 'properties' section with site configuration

B. Missing required 'kind' property for web app

C. Missing 'dependsOn' property for resource order

D. Missing 'sku' property defining pricing tier

Solution

1. Step 1: Review required properties for Microsoft.Web/sites

   Besides type, apiVersion, name, and location, a web app resource requires a properties section to define site settings.

2. Step 2: Identify missing required section

   The snippet lacks the properties section, causing deployment failure. sku and dependsOn are optional, and kind defaults to 'app' if omitted.

3. Final Answer:

   Missing 'properties' section with site configuration -> Option A

4. Quick Check:

   Web app needs properties section [OK]

Hint: Web apps require properties section; check for it [OK]

Common Mistakes:

• Assuming dependsOn is mandatory
• Confusing kind as required
• Ignoring properties section necessity

5. You want to deploy two resources in an ARM template: a storage account and a web app that uses that storage. How do you ensure the web app deploys only after the storage account is ready?

hard

A. Use the same 'apiVersion' for both resources

B. Place the web app resource before the storage account in the resources array

C. Set the web app's 'location' to the storage account's location

D. Add the storage account's name in the web app's 'dependsOn' property

Solution

1. Step 1: Understand resource deployment order control

   ARM templates use the dependsOn property to specify that one resource must finish deploying before another starts.

2. Step 2: Apply dependsOn for correct order

   Adding the storage account's resource name in the web app's dependsOn ensures the web app waits for the storage account to be ready.

3. Final Answer:

   Add the storage account's name in the web app's 'dependsOn' property -> Option D

4. Quick Check:

   dependsOn controls deployment order [OK]

Hint: Use dependsOn to order resource deployment [OK]

Common Mistakes:

• Thinking resource order in array controls deployment
• Believing apiVersion affects deployment order
• Assuming location controls deployment sequence