AWS ElasticBeanstalk helper - Only run command on one server in an EB environment.

run-on-one-server.bash

#!/bin/bash

if [ -z "$1" ]; then
 echo "Usage run-on-one-server.bash <eb-environment-name>";
 exit 0;
fi

LEADER_INSTANCE=$(aws --region us-west-2 ec2 describe-instances --filters "Name=instance-state-name,Values=running" "Name=tag:elasticbeanstalk:environment-name,Values=$1" | jq '[.Reservations[].Instances[0]] | sort_by(.LaunchTime) | .[0].InstanceId' -r)
THIS_INSTANCE=$(curl http://169.254.169.254/latest/meta-data/instance-id)

if [ "$LEADER_INSTANCE" == "$THIS_INSTANCE" ]; then
    #return success
    exit 0;
fi

#return error
exit 1;