ARM template parameters and variables in Azure - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to define a parameter named 'location' in an ARM template.

Azure

"parameters": {
  "location": {
    "type": "[1]"
  }
}

Drag options to blanks, or click blank then click option'

Aint

Bbool

Cstring

Darray

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'int' or 'bool' for a text parameter causes errors.

Forgetting to specify the type.

The 'location' parameter should be of type string because it represents a region name.

2fill in blank

medium

Complete the code to define a variable named 'storageAccountName' that concatenates 'storage' and a unique string.

Azure

"variables": {
  "storageAccountName": "concat('storage', [1])"
}

Drag options to blanks, or click blank then click option'

Aparameters('location')

BuniqueString(resourceGroup().id)

CresourceGroup().name

Dsubscription().id

Attempts:

3 left

💡 Hint

Common Mistakes

Using parameters or subscription ID directly without uniqueness.

Using resourceGroup().name which may not be unique.

The uniqueString(resourceGroup().id) function generates a unique string based on the resource group ID, ensuring the storage account name is unique.

3fill in blank

hard

Fix the error in the variable definition that tries to get the first element of a parameter array named 'vmSizes'.

Azure

"variables": {
  "firstVmSize": "[1](parameters('vmSizes'), 0)"
}

Drag options to blanks, or click blank then click option'

Aindex

Bfirst

Cparameters

Dparameters('vmSizes')[0]

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'first' which is not a valid ARM function.

Trying to use array indexing syntax directly.

The index() function is used in ARM templates to get an element at a specific position from an array.

4fill in blank

hard

Fill both blanks to define a parameter 'adminUsername' with a default value and a variable 'adminUser' that references it.

Azure

"parameters": {
  "adminUsername": {
    "type": "[1]",
    "defaultValue": "azureuser"
  }
},
"variables": {
  "adminUser": "[2]('adminUsername')"
}

Drag options to blanks, or click blank then click option'

Astring

Bint

Cparameters

Dvariables

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'int' as parameter type for a username.

Using 'variables' function to reference parameters.

The parameter type should be string. To reference a parameter inside variables, use the parameters() function.

5fill in blank

hard

Fill all three blanks to define a variable 'fullName' that combines 'firstName' and 'lastName' parameters with a space.

Azure

"variables": {
  "fullName": "concat([1]('firstName'), [2], [3]('lastName'))"
}

Drag options to blanks, or click blank then click option'

Aparameters

B' '

Dvariables

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'variables' function instead of 'parameters'.

Forgetting to add space between names.

Use the parameters() function to get both 'firstName' and 'lastName'. Insert a space string ' ' between them using concat().

Practice

1.

What is the main purpose of parameters in an ARM template?

easy

A. To define the resources to deploy

B. To allow input values when deploying the template

C. To store fixed values inside the template

D. To specify deployment location only

Solution

1. Step 1: Understand parameters role

   Parameters let users provide input values at deployment time, making templates flexible.

2. Step 2: Differentiate from variables

   Variables store fixed or computed values inside the template, not input values.

3. Final Answer:

   To allow input values when deploying the template -> Option B

4. Quick Check:

   Parameters = input values [OK]

Hint: Parameters accept inputs during deployment, variables do not [OK]

Common Mistakes:

• Confusing parameters with variables
• Thinking parameters define resources
• Assuming parameters are fixed values

2.

Which of the following is the correct syntax to declare a variable named storageAccountName in an ARM template?

{
  "variables": {
    "storageAccountName": "myStorage"
  }
}

easy

A. "resources": { "storageAccountName": "myStorage" }

B. "parameters": { "storageAccountName": "myStorage" }

C. "variables": { "storageAccountName": "myStorage" }

D. "outputs": { "storageAccountName": "myStorage" }

Solution

1. Step 1: Identify variable declaration section

   Variables are declared inside the "variables" section as key-value pairs.

2. Step 2: Match syntax with example

   The example shows "variables": { "storageAccountName": "myStorage" }, which matches "variables": { "storageAccountName": "myStorage" }.

3. Final Answer:

   "variables": { "storageAccountName": "myStorage" } -> Option C

4. Quick Check:

   Variables declared under "variables" [OK]

Hint: Variables go inside "variables" block, not parameters or resources [OK]

Common Mistakes:

• Putting variables inside parameters
• Confusing variables with outputs
• Using wrong JSON section names

3.

Given this ARM template snippet, what will be the value of variables('fullName')?

{
  "parameters": {
    "firstName": { "type": "string", "defaultValue": "John" },
    "lastName": { "type": "string", "defaultValue": "Doe" }
  },
  "variables": {
    "fullName": "[concat(parameters('firstName'), ' ', parameters('lastName'))]"
  }
}

medium

A. parameters('firstName') parameters('lastName')

B. JohnDoe

C. [concat(parameters('firstName'), ' ', parameters('lastName'))]

D. John Doe

Solution

1. Step 1: Understand concat function in variables

   The variable "fullName" uses concat to join firstName, a space, and lastName.

2. Step 2: Substitute default parameter values

   firstName = "John", lastName = "Doe", so concat("John", " ", "Doe") = "John Doe".

3. Final Answer:

   John Doe -> Option D

4. Quick Check:

   concat with space joins names [OK]

Hint: concat joins strings; default parameters fill in values [OK]

Common Mistakes:

• Taking concat as literal string
• Ignoring space between names
• Confusing parameters with variables

4.

Identify the error in this ARM template snippet:

{
  "parameters": {
    "location": { "type": "string" }
  },
  "variables": {
    "region": "parameters('location')"
  }
}

medium

A. Missing square brackets around the parameter reference in variable

B. Variable names cannot be 'region'

C. Parameter type must be 'securestring' to use in variables

D. Variables cannot reference parameters

Solution

1. Step 1: Check variable referencing syntax

   Variables referencing parameters must use expression syntax with square brackets: "[parameters('location')]".

2. Step 2: Identify missing brackets

   The variable "region" is assigned "parameters('location')" as a string, not an expression.

3. Final Answer:

   Missing square brackets around the parameter reference in variable -> Option A

4. Quick Check:

   Parameter references need [ ] in variables [OK]

Hint: Use [parameters('name')] inside variables, not plain strings [OK]

Common Mistakes:

• Omitting square brackets for expressions
• Thinking variables can't use parameters
• Wrong parameter types for variables

5.

You want to create an ARM template that deploys a storage account with a name based on a parameter prefix and a variable uniqueString. Which is the best way to combine them in the template?

{
  "parameters": {
    "prefix": { "type": "string" }
  },
  "variables": {
    "uniqueString": "[uniqueString(resourceGroup().id)]"
  },
  "resources": [
    {
      "type": "Microsoft.Storage/storageAccounts",
      "name": "???",
      "apiVersion": "2022-09-01",
      "location": "[resourceGroup().location]"
    }
  ]
}

Choose the correct expression to use for the storage account name property.

hard

A. "[concat(parameters('prefix'), variables('uniqueString'))]"

B. "parameters('prefix') + variables('uniqueString')"

C. "[parameters('prefix') variables('uniqueString')]"

D. "concat(parameters.prefix, variables.uniqueString)"

Solution

1. Step 1: Understand ARM template expression syntax

   Expressions must be inside square brackets and use functions like concat() to join strings.

2. Step 2: Check correct usage of parameters and variables

   Use parameters('name') and variables('name') inside concat() within brackets.

3. Step 3: Evaluate options

   "[concat(parameters('prefix'), variables('uniqueString'))]" uses correct syntax: "[concat(parameters('prefix'), variables('uniqueString'))]".

4. Final Answer:

   "[concat(parameters('prefix'), variables('uniqueString'))]" -> Option A

5. Quick Check:

   Use [concat(parameters('x'), variables('y'))] for combined names [OK]

Hint: Use [concat(parameters('x'), variables('y'))] for combined strings [OK]

Common Mistakes:

• Using + instead of concat inside brackets
• Omitting square brackets for expressions
• Wrong syntax for parameters or variables