Schedule a one-time and recurring task with EventBridge Scheduler and configure retry and DLQ

Steps

1. Create a one-time schedule: aws scheduler create-schedule --name my-one-time --schedule-expression 'at(2026-12-01T09:00:00)' --flexible-time-window '{"Mode": "OFF"}' --target '{"Arn": "<lambda-arn>", "RoleArn": "<role-arn>", "Input": "{\"action\": \"run\"}"}'
2. Create a recurring schedule using a cron expression: --schedule-expression 'cron(0 9 * * ? *)' for daily at 09:00 UTC
3. Set a flexible time window for rate-limiting: --flexible-time-window '{"Mode": "FLEXIBLE", "MaximumWindowInMinutes": 15}' to allow the scheduler to invoke within a 15-minute window after the scheduled time
4. Configure retry policy and DLQ on the target block: RetryPolicy with MaximumRetryAttempts (0–185) and MaximumEventAgeInSeconds (60–86400), plus DeadLetterConfig.Arn pointing to an SQS queue
5. Assign the Scheduler execution role permissions to invoke the target service (e.g., lambda:InvokeFunction) and sqs:SendMessage on the DLQ
6. Monitor failed invocations via the InvocationFailedToBeSentToDeadLetterCount CloudWatch metric on the schedule