Format CloudFormation changesets in CLI

format_changeset.py

#!/usr/bin/env python

from __future__ import print_function
from terminaltables import DoubleTable
from termcolor import colored

import sys, json

def colorize(s):
  colors = {
    "Add": "green",
    "Remove": "red",
    "Modify": "yellow"
  }
  return colored(s.upper(), colors[s]) if colors[s] else s

def table_changeset(changeset):
  table_data = [list(map(lambda x : colored(x, attrs=['bold']), ["Action", "Logical ID", "Physical ID", "Resource Type", "Replacement"]))]
  for c in changeset["Changes"]:
    if c["Type"] == "Resource":
      r = c["ResourceChange"]
      if (r["Action"] == "Add") or (r["Action"] == "Remove"):
        table_data.append([colorize(r["Action"]),
          r["LogicalResourceId"], "", r["ResourceType"], ""])
      elif r["Action"] == "Modify":
        table_data.append([colorize(r["Action"]),
          r["LogicalResourceId"], r["PhysicalResourceId"],
          r["ResourceType"], r["Replacement"]])

  table_instance = DoubleTable(table_data)
  return table_instance.table

def main():
  input = sys.stdin.read()
  changeset = json.loads(input)
  print (table_changeset(changeset))

if __name__ == '__main__':
  main()

pip install terminaltables termcolor to use. Reads STDIN and generates a table like this:

Action	Logical ID	Physical ID	Resource Type	Replacement
ADD	CloudfrontGlobalSecurityGroup		AWS::EC2::SecurityGroup
ADD	CloudfrontRegionalSecurityGroup		AWS::EC2::SecurityGroup
MODIFY	CreateInstanceCwAlarmsFunction	shared-infra-CreateInstanceCwAlarmsFunction-SFMU32II2YYN	AWS::Lambda::Function	False
MODIFY	ECSAutoScalingGroup	shared-infra-ECSAutoScalingGroup-Q2K2TR4O7PC6	AWS::AutoScaling::AutoScalingGroup	Conditional
MODIFY	ECSLaunchConfiguration	shared-infra-ECSLaunchConfiguration-1RBHVLKWP84DU	AWS::AutoScaling::LaunchConfiguration	True
MODIFY	LogsToELKFunction	shared-infra-LogsToELKFunction-1QIYG9BDN3TW9	AWS::Lambda::Function	False
ADD	ManageTopicSubscriptionFunction		AWS::Lambda::Function
ADD	ManageTopicSubscriptionRole		AWS::IAM::Role
REMOVE	ManageTopicSuscriptionFunction		AWS::Lambda::Function
REMOVE	ManageTopicSuscriptionRole		AWS::IAM::Role
MODIFY	SendToSlackFunction	shared-infra-SendToSlackFunction-1CYCDP8W951IS	AWS::Lambda::Function	False
MODIFY	SendToSlackTopic	arn:aws:sns:eu-west-1:900100097820:shared-infra-SendToSlackTopic-59TQ96JK5W31	AWS::SNS::Topic	False
ADD	SubscribeToAmazonIpChangesCustomResource		Custom::SubscribeToAmazonIpChangesFunction
REMOVE	SuscribeToAmazonIpChangesCustomResource		Custom::SuscribeToAmazonIpChangesFunction
MODIFY	UpdateCloudfrontSgFunction	shared-infra-UpdateCloudfrontSgFunction-6U78LURYT9DL	AWS::Lambda::Function	False