The giff CloudFormation differ

giff is an AWS CloudFormation stack diff tool.

• diff: shows the differences between a CloudFormation stack and a local template
• changes: creates a temporary changeset and displays an easy to read summary of the changes created by a local template and some (optional) parameters.

giff was inspired by the cliff tool you can find here: https://github.com/meetup/cliff

+     add: SampleRole2 - AWS::IAM::Role
*  modify: SampleRole (sample-giff-stack-sample-role) - AWS::IAM::Role / replacement: False / scope: Tags

Template diffing

+  SampleRole2:
+    Type: AWS::IAM::Role
+    Properties:
+      RoleName: !Sub ${AWS::StackName}-sample-role-2
+      AssumeRolePolicyDocument:
+        Version: 2012-10-17

Giff downloads the template that was used to create the specified stack, then runs the diff command over that template and a local one showing the results. By default giff uses diff -u but you can provide any command with the -d flag.

giff diff my-stack my-template.yaml -d colordiff

Showing changes with temporary changesets

giff changes sample-1-stack testdata/sample-2.yaml -p OtherPolicyArn=newArn
+     add: SampleRole2 - AWS::IAM::Role
*  modify: SampleRole (sample-giff-stack-sample-role) - AWS::IAM::Role / replacement: False / scope: Tags

If used with two arguments, the stack name and the template file, giff changes shows the changes caused by deploying the specified template file over the named stack. It will create a temporary changeset, show a easy to read list of changes, and then delete the changeset.

Flags

--parameters-overrides a partial list of parameters Param1=Value1 Param2=Value2

--all-parameters the complete listof parameters. This flag will cause an error if there are some missing parameters.

--tags tags to associate to the stack

--no-delete-changeset don't delete the temporary changeset and print its ARN

--dump print the full raw changeset in JSON format

Showing changes of existing changesets

With one single argument, a changeset ARN, giff will show a the list of changes caused by the changeset.

giff change arn:aws:cloudformation:us-east-1:123456789012:changeSet/SampleChangeSet-direct/1a2345b6-0000-00a0-a123-00abc0abc000
+     add: SampleRole2 - AWS::IAM::Role
*  modify: SampleRole (sample-giff-stack-sample-role) - AWS::IAM::Role / replacement: False / scope: Tags