How to implement “terraform apply” to update cloud infrastructure?

In the context of DevOps, here are the steps given:-

Reviewing terraform plan

Firstly, you should try to ensure that the terraform plan so that you can insert the changes that would apply to your systems.

Communication and coordination

You can communicate with the stakeholders and coordinate a suitable maintenance window to minimize the impacts on ongoing tasks.

State management

You should try to ensure that the terraform state is managed properly, either by using the remote state management or the local state file.

Apply changes

You can implement “Execute terraform apply” to implement the planned changes to your particular infrastructure.

Rollback plan

You should try to prepare a rollback plan in case of unexpected issues arise.

Validation and testing

You can validate applied changes post-deployment to ensure everything is expected.

Here is a java based example given which would simulate a simplified procedure if managing the Infrastructure changes by using the terraform concepts:-

Import java.util.*;
Public class TerraformApplySimulation {
    // Simulating infrastructure state (in real-world, this would be managed by Terraform)
    Private static Map infrastructureState = new HashMap<>();
    Public static void main(String[] args) {
        // Simulating planned changes
        Map plannedChanges = new HashMap<>();
        plannedChanges.put(“ec2_instance”, “t2.micro”);
        plannedChanges.put(“s3_bucket”, “my-bucket”);
        // Simulating current infrastructure state
        infrastructureState.put(“ec2_instance”, “t2.small”);
        infrastructureState.put(“s3_bucket”, “old-bucket”);
        // Step 1: Review Terraform plan
        System.out.println(“Terraform Plan:”);
        For (Map.Entry entry : plannedChanges.entrySet()) {
            String resource = entry.getKey();
            String desiredType = entry.getValue();
            System.out.println(“Resource: “ + resource + “, Desired Type: “ + desiredType);
        }
        // Step 2: Communication and Coordination (skipped in simulation)
        // Step 3: Apply Changes
        applyChanges(plannedChanges);
        // Step 4: Rollback Plan (skipped in simulation)
        // Step 5: Validation and Testing (skipped in simulation)
        // Step 6: Documentation and Reporting (skipped in simulation)
    }
    Private static void applyChanges(Map plannedChanges) {
        // Simulating applying changes
        System.out.println(“
Applying changes…”);
        For (Map.Entry entry : plannedChanges.entrySet()) {
            String resource = entry.getKey();
            String desiredType = entry.getValue();
            infrastructureState.put(resource, desiredType);
            System.out.println(“Applied change: Set “ + resource + “ to “ + desiredType);
        }
        System.out.println(“Changes applied successfully.”);
    }
}
Here is a python based approach given:-
# Simulate a simple infrastructure management system using Python
# Initial infrastructure state
Infrastructure_state = {
    “ec2_instance”: “t2.small”,
    “s3_bucket”: “old-bucket”
}
# Planned changes
Planned_changes = {
    “ec2_instance”: “t2.micro”,
    “s3_bucket”: “new-bucket”
}
Def review_plan(planned_changes):
    Print(“Terraform Plan:”)
    For resource, desired_state in planned_changes.items():
        Print(f”Resource: {resource}, Desired State: {desired_state}”)
Def apply_changes(planned_changes, infrastructure_state):
    Print(“
Applying changes…”)
    For resource, desired_state in planned_changes.items():
        Infrastructure_state[resource] = desired_state
        Print(f”Applied change: Set {resource} to {desired_state}”)
    Print(“Changes applied successfully.”)
    Return infrastructure_state
Def validate_changes(infrastructure_state):
    Print(“
Validating changes…”)
    For resource, state in infrastructure_state.items():
        Print(f”Resource: {resource}, Current State: {state}”)
    Print(“Validation complete.”)
Def main():
    # Step 1: Review the Terraform plan
    Review_plan(planned_changes)
    # Step 2: Communication and Coordination (skipped in simulation)
    # Step 3: Apply changes
    New_state = apply_changes(planned_changes, infrastructure_state)
    # Step 4: Rollback Plan (skipped in simulation)
    # Step 5: Validate changes
    Validate_changes(new_state)
    # Step 6: Documentation and Reporting (skipped in simulation)
If __name__ == “__main__”:
    Main()