private async Task <bool> InspectExistingAlarm(string alarmName,
double thresholdInUnits, int periodSeconds, string targetTopic)
{
var existingAlarm = await _alarmFinder.FindAlarmByName(alarmName);
if (existingAlarm == null)
{
_logger.Info($"Table alarm {alarmName} does not already exist. Creating it at threshold {thresholdInUnits}");
return(true);
}
if (!MetricAlarmHelper.AlarmActionsEqualsTarget(existingAlarm.AlarmActions, targetTopic))
{
_logger.Info($"Index alarm {alarmName} alarm target has changed to {targetTopic}");
return(true);
}
if (!MetricAlarmHelper.AlarmAndOkActionsAreEqual(existingAlarm))
{
_logger.Info($"Index alarm {alarmName} alarm actions does not match ok actions");
return(true);
}
if (AlarmThresholds.AreEqual(existingAlarm.Threshold, thresholdInUnits) && (existingAlarm.Period == periodSeconds))
{
_logger.Detail($"Table alarm {alarmName} already exists at same threshold {existingAlarm.Threshold}");
return(false);
}
LogDifferences(existingAlarm, alarmName, thresholdInUnits, periodSeconds);
return(true);
}
public async Task EnsureWriteCapacityAlarm(TableDescription table, string alarmNameSuffix, double thresholdFraction,
string snsTopicArn, bool dryRun)
{
var alarmName = GetAlarmName(table, AwsMetrics.ConsumedWriteCapacity, alarmNameSuffix);
var thresholdInUnits = AlarmThresholds.Calulate(table.ProvisionedThroughput.WriteCapacityUnits, thresholdFraction);
await CheckTableAlarm(alarmName, table.TableName, AwsMetrics.ConsumedWriteCapacity,
thresholdInUnits, AwsConstants.FiveMinutesInSeconds, snsTopicArn, dryRun);
}
public async Task EnsureReadCapacityAlarm(TableDescription table, GlobalSecondaryIndexDescription index, string alarmNameSuffix,
double thresholdFraction, string snsTopicArn, bool dryRun)
{
var alarmName = GetAlarmName(table, index, AwsMetrics.ConsumedReadCapacity, alarmNameSuffix);
var thresholdInUnits = AlarmThresholds.Calulate(index.ProvisionedThroughput.ReadCapacityUnits, thresholdFraction);
await CheckIndexAlarm(alarmName, table.TableName, index.IndexName, AwsMetrics.ConsumedReadCapacity,
thresholdInUnits, AwsConstants.FiveMinutesInSeconds, snsTopicArn, dryRun);
}
public async Task CorrectAlarmsAreCreatedForEachTable()
{
var mockery = new DynamoAlarmGeneratorMockery();
var generator = mockery.AlarmGenerator;
ConfigureTables(mockery);
await generator.GenerateAlarmsFor(ConfigWithThresholds(), RunMode.GenerateAlarms);
var expectedTable1ReadThreshold = (int)AlarmThresholds.Calulate(ReadCapacity, 0.4);
var expectedTable1WriteThreshold = (int)AlarmThresholds.Calulate(WriteCapacity, 0.4);
CloudwatchVerify.AlarmWasPutOnTable(mockery.Cloudwatch,
alarmName: "test1-ConsumedReadCapacityUnits-TestGroup",
tableName: "test1",
metricName: "ConsumedReadCapacityUnits",
threshold: expectedTable1ReadThreshold,
period: 300);
CloudwatchVerify.AlarmWasPutOnTable(mockery.Cloudwatch,
alarmName: "test1-ConsumedWriteCapacityUnits-TestGroup",
tableName: "test1",
metricName: "ConsumedWriteCapacityUnits",
threshold: expectedTable1WriteThreshold,
period: 300);
var expectedTable2ReadThreshold = (int)AlarmThresholds.Calulate(ReadCapacity, 0.65);
var expectedTable2WriteThreshold = (int)AlarmThresholds.Calulate(WriteCapacity, 0.65);
CloudwatchVerify.AlarmWasPutOnTable(mockery.Cloudwatch,
alarmName: "test2-ConsumedReadCapacityUnits-TestGroup",
tableName: "test2",
metricName: "ConsumedReadCapacityUnits",
threshold: expectedTable2ReadThreshold,
period: 300);
CloudwatchVerify.AlarmWasPutOnTable(mockery.Cloudwatch,
alarmName: "test2-ConsumedWriteCapacityUnits-TestGroup",
tableName: "test2",
metricName: "ConsumedWriteCapacityUnits",
threshold: expectedTable2WriteThreshold,
period: 300);
}
private void LogDifferences(MetricAlarm existingAlarm, string alarmName, double thresholdInUnits, int periodSeconds)
{
if (existingAlarm.Period != periodSeconds)
{
_logger.Info($"Table alarm {alarmName} period has changed from {existingAlarm.Period} to {periodSeconds}");
}
if (AlarmThresholds.AreEqual(existingAlarm.Threshold, thresholdInUnits))
{
return;
}
if (existingAlarm.Threshold < thresholdInUnits)
{
_logger.Info($"Table alarm {alarmName} already exists at lower threshold {existingAlarm.Threshold}. Will increase to {thresholdInUnits}");
}
else
{
_logger.Info($"Table alarm {alarmName} already exists at higher threshold {existingAlarm.Threshold}. Will decrease to {thresholdInUnits}");
}
}
