Which Terraform feature would help you define multiple data disks as nested blocks inside a VM resource using values from a variable?

Which Terraform feature would help you define multiple data disks as nested blocks inside a VM resource using values from a variable?

• A. Local values
• B. Collection functions
• C. Dynamic blocks
• D. Count arguments

Answer: (C)

Dynamic blocks are the tool for generating multiple nested blocks inside a resource based on a variable. When you need to define several data disks inside a VM and the number (or their details) comes from a variable, dynamic blocks let Terraform create one nested block per item in that collection. The loop uses for_each over the variable, and each iteration supplies the content for that disk (name, size, etc.). If the variable is empty, no nested blocks are produced, keeping the configuration tidy. For example, you might have a variable containing a list of disk objects, and a dynamic block inside the VM resource that iterates over that list to generate a block_device or similar nested block for each disk. This approach is preferred over hard-coding blocks, using local values to synthesize data, or trying to apply count to a nested block, because dynamic blocks specifically handle repeating nested structures within a single resource based on input data. Local values help compute or transform values but don’t create multiple nested blocks. Collection functions manipulate data but don’t generate the repeated block structure themselves. Count can create multiple instances of a resource, but nested blocks within a single resource aren’t produced by count. Dynamic blocks provide the exact mechanism to produce multiple inner blocks driven by a variable.

Dynamic blocks are the tool for generating multiple nested blocks inside a resource based on a variable. When you need to define several data disks inside a VM and the number (or their details) comes from a variable, dynamic blocks let Terraform create one nested block per item in that collection. The loop uses for_each over the variable, and each iteration supplies the content for that disk (name, size, etc.). If the variable is empty, no nested blocks are produced, keeping the configuration tidy.

For example, you might have a variable containing a list of disk objects, and a dynamic block inside the VM resource that iterates over that list to generate a block_device or similar nested block for each disk. This approach is preferred over hard-coding blocks, using local values to synthesize data, or trying to apply count to a nested block, because dynamic blocks specifically handle repeating nested structures within a single resource based on input data.

Local values help compute or transform values but don’t create multiple nested blocks. Collection functions manipulate data but don’t generate the repeated block structure themselves. Count can create multiple instances of a resource, but nested blocks within a single resource aren’t produced by count. Dynamic blocks provide the exact mechanism to produce multiple inner blocks driven by a variable.