Quick Answer
The answer is to use `count = var.create ? 1 : 0`. This is correct because Terraform’s `count` meta-argument expects a number, and the ternary expression evaluates the boolean variable: if `var.create` is true, it returns 1 to create one instance; if false, it returns 0 to create none, effectively making the resource conditional. On the HashiCorp Terraform Associate TF-003 exam, this pattern tests your understanding of how `count` works with conditional logic, often appearing as a straightforward question where the trap is confusing `count` with `for_each` or using a boolean directly (like `count = var.create`), which fails because `count` cannot accept a bool. Remember the key rule: `count` needs a number, so the ternary converts your boolean into 1 or 0. A quick memory tip: think of the ternary as a gatekeeper—true opens the gate (1 resource), false keeps it closed (0 resources).
This TF-003 practice question tests your understanding of read, generate and modify configuration. Read the scenario carefully and evaluate each option against the stated constraints before committing to an answer. After answering, compare your reasoning against the explanation and wrong-answer breakdown below. Once you have made your selection, read the full explanation to reinforce the concept and understand why each distractor is designed to mislead on exam day.
A developer wants to conditionally create a resource based on a variable that is a boolean. Which syntax should they use?
Use 'if var.create' inside the resource block
Why wrong: Conditional blocks are not supported.
Use 'for_each = var.create ? [1] : []'
Why wrong: 'for_each' expects a map or set of strings, not a boolean conditional.
Use 'count = var.create'
Why wrong: Boolean is not a number; must use ternary.
Use 'count = var.create ? 1 : 0'
Correct pattern: count with ternary.
Answer choices
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
Use 'count = var.create ? 1 : 0'
Option D is correct because in Terraform, the `count` meta-argument accepts a number, and the ternary expression `var.create ? 1 : 0` evaluates to 1 (true) to create one instance of the resource or 0 (false) to create none. This is the standard pattern for conditionally creating a single resource based on a boolean variable.
Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Answer analysis
For each option: why learners choose it and why it is or isn't the right answer here.
Use 'if var.create' inside the resource block
Why it's wrong here
Conditional blocks are not supported.
Use 'for_each = var.create ? [1] : []'
Why it's wrong here
'for_each' expects a map or set of strings, not a boolean conditional.
Use 'count = var.create'
Why it's wrong here
Boolean is not a number; must use ternary.
Use 'count = var.create ? 1 : 0'
Why this is correct
Correct pattern: count with ternary.
Related concept
Read the scenario before looking for a memorised answer.
Common exam traps
HashiCorp often tests the distinction between `count` and `for_each` for conditional creation, and the trap here is that candidates mistakenly think `count` can accept a boolean directly or that `for_each` with a single-element list is the correct approach for a simple boolean condition.
Detailed technical explanation
The `count` meta-argument is evaluated during the planning phase, and the ternary expression must resolve to a non-negative integer. When `count` is set to 0, the resource is not created at all, and any references to its attributes (e.g., `resource.name.id`) will cause a planning error unless guarded with a conditional like `try()` or `length()`. This pattern is also used with modules by passing `count = var.create ? 1 : 0` in the module block.
Key takeaway
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Real-world example
A small business has 20 workstations on the 192.168.1.0/24 network and one public IP from its ISP. The router uses PAT (NAT overload) so all 20 devices share one public address using different source ports. NAT questions test whether you understand the four address terms and which direction each translation applies.
What to study next
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FAQ
Read, generate and modify configuration — This question tests Read, generate and modify configuration — Read the scenario before looking for a memorised answer..
The correct answer is: Use 'count = var.create ? 1 : 0' — Option D is correct because in Terraform, the `count` meta-argument accepts a number, and the ternary expression `var.create ? 1 : 0` evaluates to 1 (true) to create one instance of the resource or 0 (false) to create none. This is the standard pattern for conditionally creating a single resource based on a boolean variable.
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Read the scenario before looking for a memorised answer.
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Last reviewed: Jun 30, 2026
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