How to Mock Terraform Plan and Apply in Python

This code provides a lightweight Python mock of Terraform's plan and apply commands, helping you simulate infrastructure changes without real cloud resources.

Easy Python 3.9+ Aug 9, 2026 Production deployment patterns 14 views 0 copies

terraform mock simulation deployment

Python code

30 lines

Python 3.9+

class MockTerraform:
    def __init__(self):
        self.plans = [
            {"id": 1, "action": "create", "resource": "aws_instance.web"},
            {"id": 2, "action": "update", "resource": "aws_s3_bucket.data"},
            {"id": 3, "action": "destroy", "resource": "aws_iam_user.legacy"}
        ]
        self.applied = []

    def plan(self):
        print("Terraform plan:")
        for item in self.plans:
            print(f"  {item['action']:8} {item['resource']}")
        return self.plans

    def apply(self, confirmed=False):
        if not confirmed:
            print("Apply cancelled — pass confirmed=True to apply.")
            return
        for item in self.plans:
            print(f"Applying {item['action']} {item['resource']}...")
            self.applied.append(item)
        print(f"Apply complete! {len(self.applied)} changes applied.")

if __name__ == "__main__":
    tf = MockTerraform()
    tf.plan()
    tf.apply()
    print("---")
    tf.apply(confirmed=True)

Output

stdout

Terraform plan:
  create   aws_instance.web
  update   aws_s3_bucket.data
  destroy  aws_iam_user.legacy
Apply cancelled — pass confirmed=True to apply.
---
Applying create aws_instance.web...
Applying update aws_s3_bucket.data...
Applying destroy aws_iam_user.legacy...
Apply complete! 3 changes applied.

How it works

The class holds a predefined list of changes representing a Terraform plan. The plan method prints a formatted list of actions and resources, mimicking the terraform plan command. The apply method checks a confirmed flag to avoid accidental changes, reflecting Terraform's interactive approval workflow. When confirmed, it iterates over the plan and appends each item to applied, simulating a real apply. This pattern is valuable for testing deployment scripts without touching actual infrastructure.

Common mistakes

Forgetting to reset the `applied` list between apply calls, causing incorrect counts in repeated runs.
Hardcoding the plan data inside the class instead of passing it in, making the mock less reusable.
Not including a confirmation safeguard, which defeats the purpose of simulating Terraform's safety.

Variations

Use a dataclass for each change and a list passed to the constructor for more flexibility.
Add a `dry_run` parameter that logs actions without storing them, similar to `terraform plan -out`.

Real-world use cases

Unit testing CI/CD scripts that must react to `terraform plan` output without provisioning resources.
Building a staging environment simulator for demos or training where real infrastructure is too costly.
Validating internal tooling that orchestrates Terraform runs, ensuring correct sequencing and rollback logic.

How to Mock Terraform Plan and Apply in Python

Python code

Output

How it works

Common mistakes

Variations

Real-world use cases

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Python code

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How it works

Common mistakes

Variations

Real-world use cases

More from Production deployment patterns

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