Overcast is alpha — behaviour and APIs may change between releases. Pin your version and read the changelog before upgrading.

overcast

CloudWatch operations

Every CloudWatch operation Overcast declares — 15 of 17 implemented — with status, behaviour notes and a link to the AWS API reference for each.

15 of 17 listed operations are implemented. Back to CloudWatch.

Summary

Category✅ Supported❌ Unsupported
General152

Endpoints

General

OperationStatusNotesAWS Docs
DeleteAlarms✅ SupportedDeletes one or more alarms by name, along with their historydocs
DescribeAlarmHistory✅ SupportedReturns StateUpdate, ConfigurationUpdate and Action items; filters by alarm name, item type, date range, MaxRecords and ScanBy. The most recent 100 items per alarm are retaineddocs
DescribeAlarms✅ SupportedLists alarms, supports filtering; reports the evaluator’s live StateValue, StateReason and StateReasonDatadocs
DescribeAlarmsForMetric✅ SupportedLists alarms for a specific metricdocs
DisableAlarmActions✅ SupportedClears ActionsEnabled so transitions stop firing actionsdocs
EnableAlarmActions✅ SupportedSets ActionsEnabled so transitions fire actions againdocs
GetMetricData✅ SupportedReturns query-based metric values over time ranges, over all three protocols the model declares — Query, awsJson1_0 (primary, #886) and Smithy RPC v2 CBOR (#1280) — from one shared evaluation core, so an SDK gets the same result whichever it negotiates. Merges custom PutMetricData points with automatically-recorded service metrics (AWS/Lambda’s Invocations/Errors/Duration/Throttles/ConcurrentExecutions pilot) from internal/metrics, read-through, when service-metrics collection is enableddocs
GetMetricStatistics✅ SupportedReturns aggregated datapoints by period, over Query, awsJson and rpcv2Cbor alike (#1280). Merges custom PutMetricData points with automatically-recorded service metrics from internal/metrics, so an alarm on e.g. AWS/Lambda Errors evaluates against real invocation outcomesdocs
ListMetrics✅ SupportedLists available metrics over Query, awsJson and rpcv2Cbor (#1280), merging custom PutMetricData series with automatically-recorded service metricsdocs
ListTagsForResource✅ SupportedLists tags for an alarm, over the Query, JSON and rpcv2Cbor protocols (#1280). Alarms are the only taggable CloudWatch resource Overcast emulates, so any other ResourceARN is ResourceNotFoundException — or InvalidParameterValue when it is not a CloudWatch ARN at alldocs
PutMetricAlarm✅ SupportedCreates or updates a single-metric alarm, which is then evaluated automatically (Threshold, ComparisonOperator, Period, EvaluationPeriods, DatapointsToAlarm, Dimensions, TreatMissingData). Metric-math/multi-metric alarms, anomaly detection (ThresholdMetricId) and extended statistics are created but never evaluated, and say so in the alarm’s StateReason and an x-overcast-emulation-limitation response header; PromQL alarms (EvaluationCriteria) are still refused with 501. Tags are applied at creation only and validated against the same rules as TagResource, so a create carrying an invalid tag set fails rather than leaving an untagged alarmdocs
PutMetricData✅ SupportedPublishes metric data pointsdocs
SetAlarmState✅ SupportedForces an alarm’s state and fires that state’s actions; the forced state is held against the evaluator for one evaluation rangedocs
PutAnomalyDetector❌ Unsupportedstub; returns 501 — there is no anomaly-detection model behind the emulatordocs
PutCompositeAlarm❌ Unsupportedstub; returns 501 — composite alarm rules are not evaluateddocs
TagResource✅ SupportedAdds or updates tags on an alarm, over the Query, JSON and rpcv2Cbor protocols (#1280). Tagging an alarm that does not exist is ResourceNotFoundException, as on AWS. Tag sets are validated — 50 tags per resource, keys 1-128 characters and not aws:-prefixed, values up to 256 — and a rejected set is not writtendocs
UntagResource✅ SupportedRemoves tags from an alarm, over the Query, JSON and rpcv2Cbor protocols (#1280). A key that is not present is ignored; an alarm that does not exist is ResourceNotFoundExceptiondocs