Execute use when detecting infrastructure drift from desired state. Trigger with phrases like "check for drift", "infrastructure drift detection", "compare actual vs desired state", or "detect configuration changes". Identifies discrepancies between current infrastructure and IaC definitions using terraform plan, cloudformation drift detection, or manual comparison.
!ls *.tf Dockerfile docker-compose.yml 2>/dev/null || echo 'No IaC files found'
!terraform version 2>/dev/null || echo 'Terraform not installed'
Overview
Detect discrepancies between actual cloud infrastructure state and the desired state defined in IaC (Terraform, CloudFormation, Pulumi). Run drift detection commands, analyze modified/added/deleted resources, generate drift reports with affected resources, and provide remediation steps to bring infrastructure back into compliance.
Prerequisites
IaC configuration files up to date in the project directory
Cloud provider CLI installed and authenticated with read access to all managed resources
Remote state storage accessible and current (S3 backend, Terraform Cloud, Pulumi Cloud)
Read-only IAM permissions for all resource types managed by IaC
Instructions
Identify the IaC tool in use by scanning for .tf files, template.yaml, or Pulumi.yaml
Initialize the IaC tool if needed: terraform init to download providers and configure backend
Run drift detection: terraform plan -detailed-exitcode (exit code 2 = drift detected), aws cloudformation detect-stack-drift, or pulumi preview
Parse the output to identify resources with drift: added (exists in cloud but not in IaC), modified (attributes changed), or deleted (in IaC but missing from cloud)
For each drifted resource, determine if the drift is intentional (manual hotfix) or unintentional (configuration error, unauthorized change)
Generate a structured drift report with resource identifiers, attribute differences, and severity classification
Provide remediation options per resource: terraform apply to enforce desired state, terraform import to adopt changes, or update IaC to match reality
Schedule recurring drift detection: configure a cron job or CI pipeline to run daily and alert on drift
Investigate the root cause: determine who made the manual change and implement guardrails (SCPs, IAM restrictions) to prevent recurrence
Output
Drift detection report with resource-level detail: resource type, ID, drifted attributes, expected vs. actual values
Remediation commands: terraform apply, terraform import, or IaC code updates
CI/CD pipeline step for automated drift detection on a schedule
Alert configuration for drift detection results (Slack, email, PagerDuty)
Prevention recommendations: IAM policy restrictions, SCP guardrails, automated enforcement
Error Handling
Error
Cause
Solution
Error acquiring state lock
Another Terraform process is running or stale lock
Wait for the other process; use terraform force-unlock <ID> if the lock is stale
Unable to authenticate to cloud provider
Expired or missing credentials
Refresh with aws configure, gcloud auth login, or az login
No state file found
Backend not initialized or state file deleted
Run terraform init to configure the backend; restore state from backup if deleted
Access denied reading resource
IAM policy missing read permissions for some resource types
Grant read-only access for all resource types managed by IaC (ReadOnlyAccess or specific policies)
State file version mismatch
Terraform version newer than state format
Upgrade Terraform to match the state version or use terraform state replace-provider
Examples
"Run drift detection against all Terraform-managed infrastructure and generate a report of resources that have changed since last apply."
"Set up a daily GitHub Actions workflow that runs terraform plan and posts drift results to Slack if any resources are out of sync."
"Detect CloudFormation stack drift for the production VPC stack and provide remediation steps for any MODIFIED resources."
