ARM template outputs in Azure - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ service_behavior

intermediate

What is the output value of this ARM template?

Given the following ARM template snippet, what will be the value of the output named storageAccountName after deployment?

{
  "outputs": {
    "storageAccountName": {
      "type": "string",
      "value": "myStorage123"
    }
  }
}

A "storageAccountName"

B "myStorage123"

C "string"

D "outputs"

💡 Hint

The output value is the value field inside the output definition.

The output named storageAccountName has a value of "myStorage123". This is what the deployment outputs.

🧠 Conceptual

intermediate

Which output type is valid in ARM templates?

ARM templates support several output types. Which of the following is NOT a valid output type?

A string

B securestring

C float

D int

💡 Hint

Think about the basic data types ARM templates support for outputs.

ARM templates support string, int, bool, object, and securestring as output types. float is not supported.

❓ Configuration

advanced

What is the output of this ARM template snippet with nested outputs?

Consider this ARM template outputs section:

{
  "outputs": {
    "nestedOutput": {
      "type": "object",
      "value": {
        "name": "appService",
        "id": "12345"
      }
    }
  }
}

What is the exact JSON output value for nestedOutput after deployment?

A {"name": "appService", "id": "12345"}

B "{\"name\": \"appService\", \"id\": \"12345\"}"

C "appService12345"

D {"nestedOutput": {"name": "appService", "id": "12345"}}

💡 Hint

Outputs of type object return JSON objects, not strings.

The output value is a JSON object with keys name and id. It is not a string or wrapped inside another object.

❓ security

advanced

Which output type should you use to avoid exposing sensitive data?

You want to output a secret value from your ARM template without exposing it in deployment logs or UI. Which output type should you use?

A securestring

B string

C object

D int

💡 Hint

Think about how ARM templates handle sensitive data in outputs.

The securestring output type masks the value in logs and UI, protecting secrets.

❓ Architecture

expert

What happens if an ARM template output references a non-existent resource property?

In an ARM template, an output references a property of a resource that does not exist or is misspelled. What will be the deployment output behavior?

A Deployment succeeds but output is an empty string.

B Output returns null without failing deployment.

C Deployment succeeds and output returns the property name as string.

D Deployment fails with a template validation error.

💡 Hint

Consider how ARM template validation works before deployment completes.

ARM template deployment fails if an output references a property that does not exist, as it is a template validation error.

Practice

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

easy

A. To display important information after deployment

B. To define the resources to deploy

C. To specify deployment parameters

D. To set access permissions for resources

Solution

1. Step 1: Understand the role of outputs in ARM templates

   Outputs are used to show key information after the deployment finishes, such as resource IDs or connection strings.

2. Step 2: Differentiate outputs from other template sections

   Resources define what to deploy, parameters set inputs, and outputs show results after deployment.

3. Final Answer:

   To display important information after deployment -> Option A

4. Quick Check:

   Outputs = show info after deployment [OK]

Hint: Outputs always show info after deployment [OK]

Common Mistakes:

• Confusing outputs with parameters
• Thinking outputs define resources
• Assuming outputs set permissions

2. Which of the following is the correct syntax to define an output named storageAccountName of type string in an ARM template?

easy

A. "outputs": { "storageAccountName": { "type": "string", "val": "[variables('storageName')]" } }

B. "outputs": { "storageAccountName": { "type": "string", "value": "[variables('storageName')]" } }

C. "outputs": { "storageAccountName": { "datatype": "string", "value": "[variables('storageName')]" } }

D. "outputs": { "storageAccountName": { "type": "string", "value": "variables('storageName')" } }

Solution

1. Step 1: Check the required keys for output

   An output must have a "type" key specifying the data type and a "value" key with an expression or value.

2. Step 2: Validate the syntax for referencing variables

   The value must be an expression in square brackets, e.g., "[variables('storageName')]".

3. Final Answer:

   "outputs": { "storageAccountName": { "type": "string", "value": "[variables('storageName')]" } } -> Option B

4. Quick Check:

   Output syntax = type + value with [expression] [OK]

Hint: Outputs need "type" and "value" keys with expressions in brackets [OK]

Common Mistakes:

• Using 'datatype' instead of 'type'
• Using 'val' instead of 'value'
• Missing brackets around expressions

3. Given this output snippet in an ARM template:

"outputs": { "appEndpoint": { "type": "string", "value": "[concat('https://', reference(resourceId('Microsoft.Web/sites', variables('appName'))).defaultHostName)]" }}

What will appEndpoint output after deployment?

medium

A. The app name only

B. The resource ID of the web app

C. The full URL of the deployed web app

D. An error because of wrong syntax

Solution

1. Step 1: Understand the expression used in the output value

   The expression uses concat to build a URL string starting with 'https://' and appends the defaultHostName property of the web app resource.

2. Step 2: Determine what reference() returns

   reference() fetches runtime properties of the deployed resource, here the web app's hostname.

3. Final Answer:

   The full URL of the deployed web app -> Option C

4. Quick Check:

   Output builds URL using reference() = full URL [OK]

Hint: reference() gets deployed resource info, concat builds URL [OK]

Common Mistakes:

• Thinking output returns resource ID instead of hostname
• Confusing variable name with output value
• Assuming syntax error due to complex expression

4. You have this output defined:

"outputs": { "storageKey": { "type": "string", "value": "listKeys(resourceId('Microsoft.Storage/storageAccounts', variables('storageName')), '2021-04-01').keys[0].value" }}

After deployment, you get an error. What is the likely cause?

medium

A. Missing square brackets around the expression value

B. Incorrect API version in listKeys function

C. Output type should be 'securestring' instead of 'string'

D. Variables section missing the storageName variable

Solution

1. Step 1: Check the syntax for output value expressions

   Output values must be enclosed in square brackets to indicate an expression, e.g., "[expression]".

2. Step 2: Identify the missing brackets in the given output

   The value is missing the surrounding brackets, so ARM treats it as a literal string causing an error.

3. Final Answer:

   Missing square brackets around the expression value -> Option A

4. Quick Check:

   Output expressions need [ ] brackets [OK]

Hint: Always wrap output expressions in [ ] brackets [OK]

Common Mistakes:

• Forgetting brackets around expressions
• Assuming API version is wrong without checking
• Confusing output type with expression syntax

5. You want to output a list of VM names created by a loop in your ARM template. Which output definition correctly returns an array of VM names?

hard

A. "outputs": { "vmNames": { "type": "array", "value": "[array(variables('vmNames'))]" } }

B. "outputs": { "vmNames": { "type": "object", "value": "variables('vmNames')" } }

C. "outputs": { "vmNames": { "type": "string", "value": "[variables('vmNames')]" } }

D. "outputs": { "vmNames": { "type": "array", "value": "[variables('vmNames')]" } }

Solution

1. Step 1: Identify the correct output type for a list of names

   A list of VM names is an array, so the output type should be "array".

2. Step 2: Check the syntax for output value expressions

   The value must be an expression enclosed in brackets, e.g., "[variables('vmNames')]". Wrapping with array() is unnecessary if vmNames is already an array.

3. Final Answer:

   "outputs": { "vmNames": { "type": "array", "value": "[variables('vmNames')]" } } -> Option D

4. Quick Check:

   Output array = type array + value in [ ] [OK]

Hint: Use type 'array' and wrap value in [ ] brackets [OK]

Common Mistakes:

• Using type 'string' for arrays
• Omitting brackets around expressions
• Adding unnecessary array() function