sns-topic-pruner

A tool that deletes all subscriber-less SNS topics not being used as CloudFormation stack resources in an AWS account and posts a report to slack.

In addition to the base script, a CloudFormation template is included to facilitate the creation of a scheduled Lambda.

Requirements

Alongside Python 3.11+, the following packages must be installed to run this tool:

• boto3
• requests

Additionally, you need to have both AWS CLI & AWS SAM CLI installed and configured. The following guides provide detailed instructions on how to do so:

1. Install or update the latest version of the AWS CLI
2. Set up the AWS CLI
3. Installing the AWS SAM CLI

Setup

There are two ways to use this tool: through local execution or a scheduled lambda.

Running the script locally

1. Clone this repository or download the most recent release.
2. Export a webhook to the desired Slack channel for the report as an environment variable called SLACK_WEBHOOK_URL
3. In the same folder as the script, run the following command (with the addition of any arguments from the list below):
   $ python -m sns-topic-pruner -p [PROFILES ...]

Command line argument reference:

Option	Description	Required	Default
-p, --profiles	A list of profiles to prune the topics of	Yes	N/A
-o, --override	A list of topics to ignore	No	None
-r, --regions	A list of regions to prune through	No	All Enabled Regions
-v, --verbose	Output more info in logs during execution	No	False
-d, --dry-run	Execute without making changes	No	False
-h, --help	Show help message and exit	No	N/A

Deploying the Lambda function

1. Clone this repository or download the most recent release.
2. In template.yaml, replace each commented line with relevant data. Refer to the Lambda event variable table below when filling out the Input property.
3. In sns_topic_pruner.py, replace the EXTERNAL_ID global variable string with the ExternalId specified in template.yaml.
4. In the same directory as the template file, create the build directory for the project using the following command:
   $ sam build
5. Deploy the development Lambda function and associated IAM role with the following command:
   $ sam deploy --stack-name TEXT --s3-bucket TEXT --s3-prefix TEXT --region TEXT
   OR
   Deploy the production Lambda function and associated IAM role, meaning it will run on a schedule, with the following command:
   $ sam deploy --stack-name TEXT --s3-bucket TEXT --s3-prefix TEXT --region TEXT --parameter-overrides "EnvName="prod""
   (Optional) Create an AWS SAM CLI config file to skip entering these arguments every time you want to deploy. Learn about that here.

Lambda event variable reference:

Event Variable	Description	Required	Default
account_numbers	A list of account numbers to prune the topics of	Yes	N/A
overrides	A list of topics to ignore	No	None
regions	A list of regions to prune through	No	All Enabled Regions
verbose	Output more info in logs during execution	No	True
dry_run	Execute without making changes	No	True