drift

The drift configuration can be used to control drift detection and reconciliation schedules in a repository.

Default Configuration

drift:
  enabled: false
  schedules: {}

Keys

Key	Type	Description
enabled	Boolean	Specifies whether drift detection is enabled. If set to false, drift detection and reconciliation will not run. Default is false.
schedules	Object	An object where the key is the unique name of the schedule and the value is the configuration for the schedule.

Schedule

Key	Type	Description
schedule	String	The interval to run drift detection and reconciliation: `hourly`, `daily`, `weekly`, `monthly`.
reconcile	Boolean	Specifies whether reconciliation is enabled. Default is false.
tag_query	String	A tag query that specifies which directories and workspaces drift detection and reconciliation should be applied to.
window	Object	The window that the scheduled drift can run in. Optional.

The schedule defines how frequently drift can run. There is no guarantee that drift will run as frequently as specified or when it will run. In practice, this is only relevant for hourly, as a drift run might take longer than an hour to run.

Window

Key	Type	Description
start	String	The start of the window, inclusive, in the form `HH:MM TZ`. Hour should be in 24-hour notation.
end	String	The end of the window, exclusive, in the form `HH:MM TZ`. Hour should be in 24-hour notation.

For a list of valid timezone abbreviations, see here.

Examples

Enabling Drift Detection

drift:
  enabled: true
  schedules:
    default:
      tag_query: ''
      schedule: daily

This configuration will enable drift detection and run it on a daily schedule.

Enabling Drift Detection with Reconciliation

drift:
  enabled: true
  schedules:
    default:
      tag_query: ''
      schedule: weekly
      reconcile: true

This configuration will enable drift detection with automatic reconciliation and run it on a weekly schedule.

Using Tag Queries to Limit Scope

drift:
  enabled: true
  schedules:
    prod:
      tag_query: 'dir:production'
      schedule: hourly

This configuration will enable drift detection, run it on an hourly schedule, and limit it to to the dir:production tag query.

Schedule

The schedule key can be set to one of the following values:

hourly
daily
weekly
monthly

There is no default value for schedule, and this key is required when drift detection is enabled.

Enable drift for production after work hours and development any time

drift:
  enabled: true
  schedules:
    prod:
      tag_query: 'dir:production'
      schedule: daily
      window:
        start: '18:00 EST'
        end: '07:00 EST'
    dev:
      tag_query: 'dir:dev'
      schedule: daily

This configuration runs drift daily for both production and development environments, however the production window is limited to after 6pm to 7am the next day.

Reconciliation

The reconcile key enables or disables automatic reconciliation. When enabled, if changes are found during drift detection, an apply operation will automatically run against the generated Terraform plan to reconcile the infrastructure state.

Notifications

GitHub Issues

If changes are found during drift detection, a GitHub Issue can be automatically created by adding the following configuration:

hooks:
  plan:
    post:
      - type: drift_create_issue

Duplicate issues for identical changes will not be created. GitHub Issue Drift Detected

Slack

You can create Slack notifications using the official GitHub Integration for Slack:

Install the app in your desired Slack workspace and channel.
Use the /github command to subscribe to your Terraform repository:
```
/github subscribe owner/repo issues
```

Custom Notifications

To create custom notifications or actions when drift detection finds changes, you can implement a custom hook:

hooks:
  plan:
    post:
      - type: run # run drift-notify.sh on every drift run with changes
        cmd: ['bash', '-c', '$TERRATEAM_ROOT/drift-notify.sh']

drift-notify.sh:

#!/usr/bin/env bash
set -e
if [[ "$TERRATEAM_RUN_KIND" == "drift" ]] && [[ -f "$TERRATEAM_RESULTS_FILE" ]]; then
  echo "This is a drift operation"
fi

Considerations

When configuring drift detection, keep the following in mind:

When a drift schedule is created or updated, it is immediately run.
Drift detection operations are equivalent to plan operations. Existing workflows and hooks run for all drift detection operations.
The following environment variable is defined for plan and apply operations initiated by drift detection: TERRATEAM_RUN_KIND=drift
If reconciliation is enabled, changes will be automatically applied without manual review or approval. Ensure that you have appropriate safeguards and testing in place before enabling automatic reconciliation.
Drift detection can generate a significant number of GitHub Issues if changes are frequently detected. Consider using appropriate filters, such as the tag_query key, to limit the scope of drift detection and reduce noise.
Custom notifications and actions can be implemented using hooks and scripts to integrate drift detection with your existing monitoring and alerting systems.