Bash script to send Cloud Formation signals via curl.

cfn-signal.sh

#!/bin/bash
#
# This script will signal the provided Cloud Formation URL with success or failue.
# Result is expected to be the return code of a configuration management script.
# Success will only be signaled if the script returns 0

export result=$1
export url=$2

function help {
  echo "Command Usage: $0 RESULT URL"
  exit 1
}

if [ -z $result ] || [ -z $url ]; then
  help
fi

if [ $result -eq 0 ]; then
  export status='SUCCESS'
  export reason='Command Signaled Success'
else
  export status='FAILURE'
  export reason='Command Signaled Failure'
fi

unique_id=`curl --connect-timeout 10 -s http://169.254.169.254/latest/meta-data/instance-id`
if [ -z $unique_id ]; then
  echo "Could not determine Instance ID."
  exit 1
fi

data="Return code: $result"
response="{ \"Status\" : \"$status\", \"Reason\" : \"$reason\", \"UniqueId\" : \"$unique_id\", \"Data\" : \"$data\" }"

echo "Signaling $status"

curl --connect-timeout 10 -X PUT -H "Content-Type:" --data-binary "$response" "$url"

if [ $? -ne 0 ]; then
  echo "Signaling failed."
  exit 1
fi

echo "Signaling completed successfully."

Hi, what's the header format when authentication is required?

I've never used an authenticated signal URL. If it's sig v4 you may be able to pull in code form aws-curl https://github.com/sormy/aws-curl/blob/master/aws-curl. Let us know if you get it working.