Enforcing Public Block Access on S3 Bucket automatically


I. Terraform Providers

II. Modules

  • s3-scan-public
  • IAM roles and policies
  • CloudWatch Events
  • Lambda
  • SNS Notification

III. Lambda function

$ virtualenv -p python3 venv
Running virtualenv with interpreter /usr/local/bin/python3
Using base prefix '/usr/local/Cellar/python/3.7.5/Frameworks/Python.framework/Versions/3.7'
New python executable in /Users/oli/Documents/venv/bin/python3.7
Also creating executable in /Users/oli/Documents/venv/bin/python
Installing setuptools, pip, wheel...
done.$ source venv/bin/activate

IV. SSM Parameters

  • s3-public-exception-list: List of S3 Buckets excluded from Scan(StringList type)
  • default-source-email: Default name used as a source (String type)
  • default-destination-emails: List of email recipients (StringList type)
SSM Parameters configuration

V. Deploy

21:12 $ ./python_packages.sh
Requirement already satisfied: pytest in /Users/oli/Documents/terraform_s3_public_notifications/venv/lib/python3.7/site-packages
[...]~/Documents/terraform_s3_public_notifications/modules/s3-scan-public ~/Documents/terraform_s3_public_notifications/modules-------------------------------------------------------------------
Your code has been rated at 10.00/10 (previous run: 9.22/10, +0.78)
~/Documents/terraform_s3_public_notifications/modules/s3-scan-public ~/Documents/terraform_s3_public_notifications/modules
adding: s3_public.py (deflated 70%)
21:13 $ terraform init
Initializing modules...
Initializing the backend...Initializing provider plugins...The following providers do not have any version constraints in configuration,
so the latest version was installed.
(venv) ✔ ~/Documents/terraform_s3_public_notifications [master|✔]
21:51 $ terraform apply
module.s3-public-lambda.data.aws_ssm_parameter.s3_public_emails: Refreshing state...
module.s3-public-lambda.data.aws_caller_identity.current: Refreshing state...
module.s3-public-lambda.data.aws_ssm_parameter.display_name: Refreshing state...
module.s3-public-lambda.data.template_file.cloudformation_sns_stack: Refreshing state...
[...]Plan: 15 to add, 0 to change, 0 to destroy.Do you want to perform these actions?
Terraform will perform the actions described above.
Only 'yes' will be accepted to approve.
Enter a value: yesmodule.s3-public-lambda.aws_iam_policy.s3_public_log_policy: Creating...
module.s3-public-lambda.aws_cloudwatch_event_rule.schedule: Creating...
module.s3-public-lambda.aws_iam_policy.access_ssm_policy: Creating...
module.s3-public-lambda.aws_iam_policy.access_s3_policy: Creating...
module.s3-public-lambda.aws_iam_role.lambda_s3_public_role: Creating...
module.s3-public-lambda.aws_cloudformation_stack.sns_topic: Creating...
Confirmation email of subscription

VI. Details of this repository

  • List all your existing buckets
  • Compare this list with the exempt list of S3 Buckets present in your SSM parameter
  • Check if Public Access Block ACL is applied on each of your bucket
  • Apply Public Access Block ACL on your bucket if it wasn’t apply
  • Notify by SNS notification

VII. Testing

AWS Lambda test
Email notification




Cloud technologies and solutions lover, https://cdcloudlogix.com

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Olivier Butterbach

Olivier Butterbach

Cloud technologies and solutions lover, https://cdcloudlogix.com

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