ARM template outputs in Azure - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is the purpose of outputs in an ARM template?

Outputs in an ARM template provide information about the deployed resources, such as resource IDs or connection strings, which can be used after deployment.

beginner

How do you define an output value in an ARM template?

You define an output by specifying a name, type, and value inside the outputs section of the ARM template JSON.

intermediate

Which data types are valid for ARM template outputs?

Valid output data types include string, int, bool, array, and object.

intermediate

Can ARM template outputs reference resource properties?

Yes, outputs can reference properties of deployed resources using functions like reference() or resourceId().

intermediate

Why is it useful to use outputs in ARM templates when chaining deployments?

Outputs allow passing important information from one deployment to another, enabling automation and integration between resources.

What section in an ARM template contains the output values?

A resources

B outputs

C variables

D parameters

The outputs section is where you define values to return after deployment.

Which of the following is NOT a valid output data type in ARM templates?

A float

B int

C string

D array

ARM templates do not support float as an output data type.

How can you get the resource ID of a deployed resource in an output?

A Using the <code>resourceId()</code> function

B Using the <code>concat()</code> function only

C Using the <code>parameters()</code> function

D Using the <code>variables()</code> function

The resourceId() function returns the resource ID for a given resource.

Can outputs be used to pass data between ARM template deployments?

A No, outputs are only for display

B Only if the deployment is manual

C Yes, outputs can be consumed by other deployments

D Only for virtual machines

Outputs can be used to pass data between deployments for automation.

Which keyword is required when defining an output in an ARM template?

A dependsOn

B location

C name

D type

Each output must specify a type to indicate the data type of the output value.

Explain how outputs in ARM templates help after resource deployment.

Think about what you want to know after your cloud resources are created.

Describe how to define an output in an ARM template with an example.

Look at the JSON structure for outputs.

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