Module versioning in Terraform - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is module versioning in Terraform?

Module versioning in Terraform means keeping track of different versions of a module so you can use a specific, stable version in your infrastructure code.

beginner

Why should you use versioned modules in Terraform?

Using versioned modules helps avoid unexpected changes by locking your infrastructure to a tested module version, making your deployments more reliable.

beginner

How do you specify a module version in Terraform?

You specify a module version by adding a version argument in the module block, like:
module "example" {
source = "registry.terraform.io/hashicorp/example"
version = "1.2.0"
}

intermediate

What happens if you don’t specify a module version?

If you don’t specify a version, Terraform uses the latest available module version, which might cause unexpected changes if the module updates.

intermediate

How can you update a module to a newer version safely?

To update safely, change the version number in your module block, run terraform init -upgrade to download the new version, then test your infrastructure.

What is the purpose of specifying a module version in Terraform?

A To lock the module to a specific stable version

B To automatically upgrade to the latest module version

C To delete old versions of the module

D To run the module faster

Specifying a module version locks your infrastructure to a known stable version, preventing unexpected changes.

Which command updates Terraform modules to the latest allowed version?

A terraform destroy

B terraform apply

C terraform plan

D terraform init -upgrade

terraform init -upgrade downloads the latest module versions allowed by your version constraints.

What happens if you omit the version argument in a Terraform module source?

A Terraform uses the latest module version

B Terraform throws an error

C Terraform uses a random module version

D Terraform disables the module

Without a version, Terraform defaults to the latest available module version.

Why is it risky to always use the latest module version without specifying a version?

A It disables module caching

B It makes Terraform run slower

C It can cause unexpected infrastructure changes

D It deletes your state file

Using the latest version can introduce changes you did not test, risking your infrastructure stability.

How do you specify a module version in Terraform code?

A source_version = "1.0.0" inside the provider block

B version = "1.0.0" inside the module block

C module_version = "1.0.0" outside the module block

D version = "latest" inside the resource block

You specify the version inside the module block with the argument version = "1.0.0".

Explain what module versioning is in Terraform and why it is important.

Think about how using a fixed version helps keep your infrastructure predictable.

Describe the steps to safely update a Terraform module to a newer version.

Consider how you control the version and apply the update carefully.

Practice

1. What is the main purpose of specifying a version when using a Terraform module from a registry?

easy

A. To speed up Terraform plan execution

B. To enable local module usage

C. To automatically update the module to the latest version

D. To keep your infrastructure stable by locking the module version

Solution

1. Step 1: Understand module versioning purpose

   Specifying a version locks the module to a specific release, preventing unexpected changes.

2. Step 2: Compare options

   Only locking the version ensures stability; automatic updates or speed improvements are not guaranteed by versioning.

3. Final Answer:

   To keep your infrastructure stable by locking the module version -> Option D

4. Quick Check:

   Module versioning = Stability [OK]

Hint: Version locks module to prevent unexpected changes [OK]

Common Mistakes:

• Thinking version speeds up execution
• Assuming version auto-updates modules
• Confusing local modules with versioned modules

2. Which of the following is the correct syntax to specify a module version from the Terraform Registry?

easy

A. module "example" { source = "registry/module" version = "1.2.0" }

B. module "example" { source = "registry/module" ver = "1.2.0" }

C. module "example" { source = "registry/module" version: "1.2.0" }

D. module "example" { source = "registry/module" v = "1.2.0" }

Solution

1. Step 1: Recall correct version attribute

   The correct attribute to specify module version is version with an equals sign.

2. Step 2: Check syntax correctness

   module "example" { source = "registry/module" version = "1.2.0" } uses correct attribute and syntax; others use incorrect attribute names or syntax.

3. Final Answer:

   module "example" { source = "registry/module" version = "1.2.0" } -> Option A

4. Quick Check:

   Correct attribute is version = "x.y.z" [OK]

Hint: Use 'version = "x.y.z"' exactly for module versions [OK]

Common Mistakes:

• Using 'ver' or 'v' instead of 'version'
• Using colon instead of equals sign
• Omitting quotes around version number

3. Given this Terraform module block:

module "network" {
  source  = "terraform-aws-modules/vpc/aws"
  version = "3.0.0"
}

What happens if a newer version 3.1.0 is released and you run terraform init without changing the version?

medium

A. Terraform upgrades the module to version 3.1.0 automatically

B. Terraform uses version 3.0.0 and does not upgrade automatically

C. Terraform throws an error about version mismatch

D. Terraform ignores the version and uses the latest

Solution

1. Step 1: Understand version locking behavior

   Specifying version "3.0.0" locks the module to that exact version.

2. Step 2: Effect of terraform init

   Running terraform init downloads the locked version; it does not upgrade unless version is changed.

3. Final Answer:

   Terraform uses version 3.0.0 and does not upgrade automatically -> Option B

4. Quick Check:

   Locked version stays fixed until changed [OK]

Hint: Locked version stays fixed unless manually updated [OK]

Common Mistakes:

• Assuming terraform init upgrades modules automatically
• Expecting errors on version mismatch
• Thinking latest version is always used

4. You have this module block:

module "db" {
  source = "git::https://github.com/example/db-module.git"
}

You want to use a specific version tag v1.4.2. What is missing?

medium

A. Add tag = "v1.4.2" inside the block

B. Add version = "v1.4.2" inside the block

C. Add ?ref=v1.4.2 to the source URL

D. Nothing, it uses latest by default

Solution

1. Step 1: Understand versioning for Git modules

   Git modules use URL query parameter ?ref= to specify version or tag.

2. Step 2: Identify correct way to specify tag

   Adding ?ref=v1.4.2 to source URL locks module to that tag.

3. Final Answer:

   Add ?ref=v1.4.2 to the source URL -> Option C

4. Quick Check:

   Git module version = source URL + ?ref=tag [OK]

Hint: Use ?ref=tag in Git source URL for versioning [OK]

Common Mistakes:

• Using version attribute for Git modules
• Using tag attribute which does not exist
• Assuming latest is always used without specifying ref

5. You have a local module at ./modules/app and a remote module from the registry. You want to ensure only the remote module uses versioning. How should you configure the modules?

hard

A. Specify version only for the remote module; omit for local module

B. Specify version for both local and remote modules

C. Specify version only for the local module

D. Omit version for both modules

Solution

1. Step 1: Recall versioning rules for local modules

   Local modules do not support versioning; version attribute is ignored or causes error.

2. Step 2: Apply version only to remote modules

   Only remote modules from registries or Git support versioning and require version locking.

3. Final Answer:

   Specify version only for the remote module; omit for local module -> Option A

4. Quick Check:

   Version only for remote modules [OK]

Hint: Version attribute only for remote modules, never local [OK]

Common Mistakes:

• Adding version to local modules causing errors
• Omitting version for remote modules causing instability
• Confusing local and remote module versioning rules