formica diff

Through the diff command you can see exactly what changed in your template compared to what is already deployed in your stack. It uses DeepDiff to compare the two templates and show you detailed results.

Following is an example where we have two S3 Buckets and want to add a specific BucketName for one and change the BucketName of the second.

root@61aaad32daf7:/app/docs/examples/s3-bucket# formica diff --stack teststack
+---------------------------------------------------------+------------------+----------------------------------+-----------------------+
|                          Path                           |       From       |                To                |      Change Type      |
+=========================================================+==================+==================================+=======================+
| Resources > DeploymentBucket > Properties               | Not Present      | {'BucketName': 'another-bucket'} | Dictionary Item Added |
+---------------------------------------------------------+------------------+----------------------------------+-----------------------+
| Resources > DeploymentBucket2 > Properties > BucketName | a-formica-bucket | a-bucket                         | Values Changed        |
+---------------------------------------------------------+------------------+----------------------------------+-----------------------+

As you can see it will show the path of the property that was changed, what it was before and after and what kind of change it was.

Together with formica describe you can understand exactly what has changed in your template and how that will influence your deployed stack.

Usage

usage: formica diff [-h] [--region REGION] [--profile PROFILE] [--stack STACK]
                    [--config-file CONFIG_FILE [CONFIG_FILE ...]]
                    [--vars KEY=Value [KEY=Value ...]]
                    [--parameters KEY=Value [KEY=Value ...]]
                    [--tags KEY=Value [KEY=Value ...]]
                    [--organization-variables]
                    [--organization-region-variables]
                    [--organization-account-variables]
                    [--artifacts ARTIFACTS [ARTIFACTS ...]]

Print a diff between local and deployed stack

options:
  -h, --help            show this help message and exit
  --region REGION       The AWS region to use
  --profile PROFILE     The AWS profile to use
  --stack STACK, -s STACK
                        The Stack to use
  --config-file CONFIG_FILE [CONFIG_FILE ...], -c CONFIG_FILE [CONFIG_FILE ...]
                        Set the config files to use
  --vars KEY=Value [KEY=Value ...]
                        Add one or multiple Jinja2 variables
  --parameters KEY=Value [KEY=Value ...]
                        Add one or multiple stack parameters
  --tags KEY=Value [KEY=Value ...]
                        Add one or multiple stack tags
  --organization-variables
                        Add AWSAccounts, AWSSubAccounts, AWSMainAccount and
                        AWSRegions as Jinja variables with an Email, Id and
                        Name field for each account
  --organization-region-variables
                        Add AWSRegions as Jinja variables
  --organization-account-variables
                        Add AWSAccounts, AWSSubAccounts, and AWSMainAccount as
                        Jinja variables with an Email, Id, and Name field for
                        each account
  --artifacts ARTIFACTS [ARTIFACTS ...]
                        Add one or more artifacts to push to S3 before
                        deployment