AWS AutoScaling provides a mechanism for performing custom actions when Auto Scaling launches or terminates an instance in your AutoScaling group. lifecycled provides a way to consume these events and respond with simple shell scripts.

Lifecycle events are consumed from an SQS queue and a corresponding hook is executed. Whilst the hook is executing lifecycled sends heartbeats to the Autoscaling group to stall further action. When the hook completes executing, if it completes successfully the lifecycle action is completed successfully, if the hook returns a non-zero exit code then the lifecycle action is abandoned.

cat << EOF > handler.sh
#!/bin/bash
echo got a $1 event
sleep 25
EOF

chmod +x handler.sh
go run ./cli/lifecycled/*.go --queue simulate --handler ./test.sh --instanceid llamas

glide install
docker build --tag lifecycled-builder release/
docker run --rm -v "$PWD":/go/src/github.com/lox/lifecycled lifecycled-builder
ls -al builds/