Small service for creating a custom metric of high temporal resolution for ApproximateNumberOfMessages in an SQS queue.
This can be very handy for fast scaling as per default, the respective CloudWatch metric has a 5min resolution only.
See also https://aws.amazon.com/blogs/aws/auto-scaling-with-sqs/
Running this service will incur costs!
- Adjust Makefile to suit your docker registry
- If you happen to not build with Bamboo, adjust the push scenario in Makefile
- Create a version.txt file if you want custom tagging.
The format is
version=<version-tag>and the default created one is a timestamp. make docker-build && make docker-push- Run container. Default scenario is as a service in ECS, YMMV. You will need to provide permissions for reading the queue attributes and writing metrics, preferably by assuming a role in the execution environment.
- Make use of the metrics!
The following environment variables will get used when a container is run:
| env variable | purpose |
|---|---|
| WAIT_TIME_IN_SECONDS | This is the wait time inbetween subsequent calls to the queue and defines the resolution of the metric. 10s = roughly 6 datapoints per minute, but beware of the runtime of queue-attribute poll and metrics push. |
| QUEUE_NAME | The queue in question. This will show up as dimension QueueName in the metrics |
| ENVIRONMENT | This will show up as dimension env in the metrics and supports different metrics for dev, prod and other stages |
| METRICS_NAMESPACE | Namespace for the custom metrics. |
| LOG_LEVEL | Default is INFO, DEBUG will emit a message each loop |
| LOG_FORMAT | Default is plaintext, json will emit JSON which might be handy for a log aggregator. There are quite a few other environment variables picked up for logging, which might need to get adjusted in the code if desired. |