Synthetic Monitoring custom labels: label_ prefix removed, labels attach to all check telemetry

Custom labels in Grafana Cloud Synthetic Monitoring now attach directly to every check metric and log - not only the sm_check_info metric - and the label_ prefix is removed.

Labels will appear exactly as you define them. A three-stage migration (prefixed → dual-write → un-prefixed) is open now. Support for the legacy prefixed behavior ends March 1, 2027, after which any stack not yet migrated will be auto-migrated by Grafana Labs.

Why we’re changing it

Previously, filtering a dashboard, scoping an alert, or attributing cost by team or service required joining sm_check_info against the check metric you actually wanted, and remembering that team actually renders as label_team. This made Synthetic Monitoring an exception to how labels work everywhere else in Grafana Cloud.

With labels on the metrics themselves, a single alert rule can route by team, Cost Management can attribute usage by your own dimensions, and there is no separate label convention to learn.

Read the blog post for more detail.

What is not changing

If you do not use custom labels in Synthetic Monitoring, nothing changes and no action is needed. System-defined labels are unaffected. Historical data is not lost: everything already collected remains queryable under its original label names for your retention window, during and after migration.

The migration does not increase cardinality or cost; the dual-write period where both label sets exist is absorbed by 95th-percentile billing and is not billed as additional active series.

What to check before this rolls out

• If you use custom labels in Synthetic Monitoring, check them against the reserved system labels list. Migration will be rejected if any of your labels collide with a reserved value.
• Follow the label migration guide to enable dual-write, update dashboards, SLOs, alerts, and queries that reference label_-prefixed labels or join on sm_check_info, then retire the prefixed labels. Admin access is required.
• Complete the migration before March 1, 2027 so you control the timing rather than being auto-migrated.
• If you do not use custom labels in Synthetic Monitoring, no action is needed.