Extracting EC2InstanceId from SNS/SQS Auto Scaling message

Question

I'm using python Boto3 code, when an instance is terminated from Auto Scaling group it notifies SNS which publishes the message to SQS. Lambda is also triggered when SNS is notified, which executes a boto script to grab the message from SQS.

I am using reference code from Sending and Receiving Messages in Amazon SQS.

Here is the code snippet:

if messages.get('Messages'):
  m = messages.get('Messages')[0]
  body = m['Body']

  print('Received and deleted message: %s' % body)

The result is:

START RequestId: 1234-xxxxxxxx Version: $LATEST
 {
  "Type" : "Notification",
  "MessageId" : "d1234xxxxxx",
  "TopicArn" : "arn:aws:sns:us-east-1:xxxxxxxxxx:AutoScale-Topic",
  "Subject" : "Auto Scaling: termination for group \"ASG\"",
  "Message" : "{\"Progress\":50,\"AccountId\":\"xxxxxxxxx\",\"Description\":\"Terminating EC2 instance: i-123456\",\"RequestId\":\"db-xxxxx\",\"EndTime\":\"2017-07-13T22:17:19.678Z\",\"AutoScalingGroupARN\":\"arn:aws:autoscaling:us-east-1:360695249386:autoScalingGroup:fef71649-b184xxxxxx:autoScalingGroupName/ASG\",\"ActivityId\":\"db123xx\",\"EC2InstanceId\":\"i-123456\",\"StatusCode\"\"}",
  "Timestamp" : "2017-07-",
  "SignatureVersion" : "1",
  "Signature" : "",
  "SigningCertURL" : "https://sns.us-east-1.amazonaws.com/..",
  "UnsubscribeURL" : "https://sns.us-east-1.amazonaws.com/
}

I only need EC2InstanceId of the terminated instance not the whole message. How can I extract the ID?

Extracting EC2InstanceId from SNS/SQS Auto Scaling message

2 Answers