Post a Slack notification to a channel when an AWS ECS task goes into an unexpected STOPPED status.

1. Create a AWS Lambda function named ecs-deploy-watchguard using the Node.js 12.X runtime. Set the basic setting timeout to something reasonable like 10 seconds from the default to allow for Slack API slowness.

2. Create a webhook in Slack and set the environment variable SLACK_WEBHOOK_URL in the AWS Lambda function.

3. Navigate to CloudWatch and then to Events => Rules. Create a new rule with the following: