ref(crons): Add migration to backfill MonitorEnvironment.is_muted

Implements Step 2 of the migration plan from [NEW-564: There needs to be some way to mute the entire cron detector](https://linear.app/getsentry/issue/NEW-564/there-needs-to-be-some-way-to-mute-the-entire-cron-detector)

This data migration backfills MonitorEnvironment.is_muted from Monitor.is_muted for all muted monitors. This ensures existing data is consistent before switching to read from MonitorEnvironment.is_muted.

After this migration runs:
- Monitors with is_muted=True will have ALL environments muted
- Monitors with is_muted=False will have environments unchanged

This establishes the correct invariant:
- Monitor is muted ↔ ALL environments are muted
- Monitor is unmuted ↔ ANY environment is unmuted

The migration:
- Uses range queries for efficient batching (1000 monitors per batch)
- Only updates environments for muted monitors (unmuted is the default)
- Is marked as post-deployment for manual execution in production

Test verifies:
- Muted monitor environments are updated to is_muted=True
- Unmuted monitor environments remain unchanged
- Monitors without environments are unaffected

Author: evanpurkhiser

migrations_lockfile.txt

@@ -17,7 +17,7 @@ hybridcloud: 0024_add_project_distribution_scope
 
 insights: 0002_backfill_team_starred
 
-monitors: 0010_delete_orphaned_detectors
+monitors: 0011_backfill_monitor_environment_is_muted
 
 nodestore: 0001_squashed_0002_nodestore_no_dictfield
 

src/sentry/monitors/migrations/0011_backfill_monitor_environment_is_muted.py

@@ -0,0 +1,61 @@
+# Generated by Django 5.2.1 on 2025-11-13 19:27
+
+from django.db import migrations
+from django.db.backends.base.schema import BaseDatabaseSchemaEditor
+from django.db.migrations.state import StateApps
+
+from sentry.new_migrations.migrations import CheckedMigration
+from sentry.utils.query import RangeQuerySetWrapperWithProgressBar
+
+
+def backfill_monitor_environment_is_muted(
+    apps: StateApps, schema_editor: BaseDatabaseSchemaEditor
+) -> None:
+    """
+    Backfill MonitorEnvironment.is_muted from Monitor.is_muted for all muted monitors.
+
+    After this migration:
+    - is_muted=True monitors will have ALL environments muted
+    - is_muted=False monitors will have environments unchanged (some, none, or all unmuted)
+
+    This gets us into the correct state for the dual-write implementation where:
+    - Monitor is muted if and only if ALL environments are muted
+    - Monitor is unmuted if ANY environment is unmuted
+    """
+    Monitor = apps.get_model("monitors", "Monitor")
+    MonitorEnvironment = apps.get_model("monitors", "MonitorEnvironment")
+
+    # Filter is_muted in memory to avoid query timeouts (no composite index on id, is_muted)
+    all_monitors = Monitor.objects.all()
+
+    for monitor in RangeQuerySetWrapperWithProgressBar(all_monitors):
+        if monitor.is_muted:
+            MonitorEnvironment.objects.filter(monitor=monitor).update(is_muted=True)
+
+
+class Migration(CheckedMigration):
+    # This flag is used to mark that a migration shouldn't be automatically run in production.
+    # This should only be used for operations where it's safe to run the migration after your
+    # code has deployed. So this should not be used for most operations that alter the schema
+    # of a table.
+    # Here are some things that make sense to mark as post deployment:
+    # - Large data migrations. Typically we want these to be run manually so that they can be
+    #   monitored and not block the deploy for a long period of time while they run.
+    # - Adding indexes to large tables. Since this can take a long time, we'd generally prefer to
+    #   run this outside deployments so that we don't block them. Note that while adding an index
+    #   is a schema change, it's completely safe to run the operation after the code has deployed.
+    # Once deployed, run these manually via: https://develop.sentry.dev/database-migrations/#migration-deployment
+
+    is_post_deployment = True
+
+    dependencies = [
+        ("monitors", "0010_delete_orphaned_detectors"),
+    ]
+
+    operations = [
+        migrations.RunPython(
+            backfill_monitor_environment_is_muted,
+            migrations.RunPython.noop,
+            hints={"tables": ["monitors_monitor", "monitors_monitorenvironment"]},
+        ),
+    ]

tests/sentry/monitors/migrations/test_0008_fix_processing_error_keys.py

@@ -1,5 +1,6 @@
 from typing import Any
 
+import pytest
 from django.conf import settings
 
 from sentry.monitors.processing_errors.errors import ProcessingErrorType
@@ -18,6 +19,7 @@ def _get_cluster() -> Any:
     return redis.redis_clusters.get(settings.SENTRY_MONITORS_REDIS_CLUSTER)
 
 
+@pytest.mark.skip(reason="migration test no longer needed")
 class FixProcessingErrorKeysTest(TestMigrations):
     migrate_from = "0007_monitors_json_field"
     migrate_to = "0008_fix_processing_error_keys"

tests/sentry/monitors/migrations/test_0010_delete_orphaned_detectors.py

@@ -1,9 +1,12 @@
+import pytest
+
 from sentry.monitors.types import DATA_SOURCE_CRON_MONITOR
 from sentry.monitors.utils import ensure_cron_detector, get_detector_for_monitor
 from sentry.testutils.cases import TestMigrations
 from sentry.workflow_engine.models import DataSource, DataSourceDetector, Detector
 
 
+@pytest.mark.skip(reason="migration test no longer needed")
 class DeleteOrphanedDetectorsTest(TestMigrations):
     migrate_from = "0009_backfill_monitor_detectors"
     migrate_to = "0010_delete_orphaned_detectors"

tests/sentry/monitors/migrations/test_0011_backfill_monitor_environment_is_muted.py

@@ -0,0 +1,73 @@
+from sentry.testutils.cases import TestMigrations
+
+
+class BackfillMonitorEnvironmentIsMutedTest(TestMigrations):
+    migrate_from = "0010_delete_orphaned_detectors"
+    migrate_to = "0011_backfill_monitor_environment_is_muted"
+    app = "monitors"
+    connection = "secondary"
+
+    def setup_initial_state(self) -> None:
+        # Create muted monitor with environments
+        self.muted_monitor = self.create_monitor(name="Muted Monitor", is_muted=True)
+        self.muted_env1 = self.create_monitor_environment(
+            monitor=self.muted_monitor,
+            environment_id=self.environment.id,
+            is_muted=False,  # Initially not muted
+        )
+        env2 = self.create_environment(name="production", project=self.project)
+        self.muted_env2 = self.create_monitor_environment(
+            monitor=self.muted_monitor,
+            environment_id=env2.id,
+            is_muted=False,  # Initially not muted
+        )
+
+        # Create unmuted monitor with environments
+        self.unmuted_monitor = self.create_monitor(name="Unmuted Monitor", is_muted=False)
+        self.unmuted_env1 = self.create_monitor_environment(
+            monitor=self.unmuted_monitor,
+            environment_id=self.environment.id,
+            is_muted=False,
+        )
+        env3 = self.create_environment(name="staging", project=self.project)
+        self.unmuted_env2 = self.create_monitor_environment(
+            monitor=self.unmuted_monitor,
+            environment_id=env3.id,
+            is_muted=False,
+        )
+
+        # Create muted monitor without environments
+        self.muted_monitor_no_envs = self.create_monitor(
+            name="Muted Monitor No Envs", is_muted=True
+        )
+
+        # Verify initial state
+        assert self.muted_monitor.is_muted is True
+        assert self.muted_env1.is_muted is False
+        assert self.muted_env2.is_muted is False
+        assert self.unmuted_monitor.is_muted is False
+        assert self.unmuted_env1.is_muted is False
+        assert self.unmuted_env2.is_muted is False
+
+    def test(self) -> None:
+        # Refresh from DB to get updated state after migration
+        self.muted_monitor.refresh_from_db()
+        self.muted_env1.refresh_from_db()
+        self.muted_env2.refresh_from_db()
+        self.unmuted_monitor.refresh_from_db()
+        self.unmuted_env1.refresh_from_db()
+        self.unmuted_env2.refresh_from_db()
+        self.muted_monitor_no_envs.refresh_from_db()
+
+        # Verify muted monitor has all environments muted
+        assert self.muted_monitor.is_muted is True
+        assert self.muted_env1.is_muted is True
+        assert self.muted_env2.is_muted is True
+
+        # Verify unmuted monitor environments remain unchanged
+        assert self.unmuted_monitor.is_muted is False
+        assert self.unmuted_env1.is_muted is False
+        assert self.unmuted_env2.is_muted is False
+
+        # Verify muted monitor without environments still muted
+        assert self.muted_monitor_no_envs.is_muted is True

tests/sentry/workflow_engine/migrations/test_0069_rename_error_detectors.py

@@ -1,6 +1,9 @@
+import pytest
+
 from sentry.testutils.cases import TestMigrations
 
 
+@pytest.mark.skip(reason="migration test no longer needed")
 class RenameErrorDetectorsTest(TestMigrations):
     app = "workflow_engine"
     migrate_from = "0068_migrate_anomaly_detection_alerts"

tests/sentry/workflow_engine/migrations/test_0078_update_metric_detector_config_fields.py

@@ -3,7 +3,7 @@
 from sentry.testutils.cases import TestMigrations
 
 
-@pytest.mark.skip
+@pytest.mark.skip(reason="migration test no longer needed")
 class UpdateMetricDetectorConfigFieldsTest(TestMigrations):
     migrate_from = "0079_add_unique_constraint_to_detector_group"
     migrate_to = "0080_update_metric_detector_config_fields"

tests/sentry/workflow_engine/migrations/test_0086_fix_cron_to_cron_workflow_links.py

@@ -1,3 +1,5 @@
+import pytest
+
 from sentry.models.rule import Rule, RuleSource
 from sentry.testutils.cases import TestMigrations
 from sentry.workflow_engine.migration_helpers.issue_alert_migration import IssueAlertMigrator
@@ -9,6 +11,7 @@
 )
 
 
+@pytest.mark.skip(reason="migration test no longer needed")
 class FixCronToCronWorkflowLinksTest(TestMigrations):
     migrate_from = "0085_crons_link_detectors_to_all_workflows"
     migrate_to = "0086_fix_cron_to_cron_workflow_links"

tests/sentry/workflow_engine/migrations/test_0089_update_cron_workflow_names.py

@@ -1,3 +1,5 @@
+import pytest
+
 from sentry.testutils.cases import TestMigrations
 from sentry.workflow_engine.models import (
     Action,
@@ -10,6 +12,7 @@
 )
 
 
+@pytest.mark.skip(reason="migration test no longer needed")
 class TestUpdateCronWorkflowNames(TestMigrations):
     migrate_from = "0088_remove_monitor_slug_conditions"
     migrate_to = "0089_update_cron_workflow_names"

tests/sentry/workflow_engine/migrations/test_0091_fix_email_notification_names.py

@@ -1,3 +1,5 @@
+import pytest
+
 from sentry.testutils.cases import TestMigrations
 from sentry.workflow_engine.models import (
     Action,
@@ -10,6 +12,7 @@
 )
 
 
+@pytest.mark.skip(reason="migration test no longer needed")
 class TestFixEmailNotificationNames(TestMigrations):
     migrate_from = "0090_add_detectorgroup_detector_date_index"
     migrate_to = "0091_fix_email_notification_names"