Skip to content
Rules engine for cloud security, cost optimization, and governance, DSL in yaml for policies to query, filter, and take actions on resources
Branch: master
Clone or download
Type Name Latest commit message Commit time
Failed to load latest commit information.
.vscode c7n_azure - filters running against azure resources (#2172) Mar 28, 2018
c7n aws - config recorder resource (#2367) Apr 26, 2019
docs Azure - Key Vault Update Access Policy Action (#3836) Apr 26, 2019
tests aws - config recorder resource (#2367) Apr 26, 2019
tools tools/dev - support doc builds in docker (#3882) Apr 26, 2019
.azure-pipelines.yml windows test pass support (#3842) Apr 23, 2019
.codecov.yml k8s - unit tests, expand resource across core and apps v1 apis (#3312) Jan 12, 2019
.coveragerc vendor to address py2/py3 mismatches (py3 cli->py2 run) (#… Dec 21, 2017
.dockerignore tools/c7n-mailer - redo c7n-mailer docker packaging for azure support ( Apr 24, 2019
.gitignore azure - set network rules storage (#3797) Apr 25, 2019
.travis.yml ci - code coverage from azure pipeline (#3250) Dec 17, 2018
Dockerfile core - update docker image with multi-cloud packages, py3 base, image… Jan 11, 2019
LICENSE.txt update copyright in license addendum example (#1541) Sep 6, 2017
Makefile core - refactor outputs add policy api/processs stats and tracing (#2844 Oct 4, 2018
README.rst docs - readme update coverage and gitter links (#3878) Apr 26, 2019
requirements-dev.txt docs - validation test for policies in doc strings (#3767) Apr 12, 2019
requirements.txt core - dependency updates and document pinned versions w/ known issues ( Feb 20, 2019 - release (#3810) Apr 17, 2019
tox.ini ci - doc test enable json schema validation (#3809) Apr 17, 2019


Join the chat at Build Status License Coverage Requirements Status

Cloud Custodian

Cloud Custodian is a rules engine for managing public cloud accounts and resources. It allows users to define policies to enable a well managed cloud infrastructure, that's both secure and cost optimized. It consolidates many of the adhoc scripts organizations have into a lightweight and flexible tool, with unified metrics and reporting.

Custodian can be used to manage AWS, Azure, and GCP environments by ensuring real time compliance to security policies (like encryption and access requirements), tag policies, and cost management via garbage collection of unused resources and off-hours resource management.

Custodian policies are written in simple YAML configuration files that enable users to specify policies on a resource type (EC2, ASG, Redshift, CosmosDB, PubSub Topic) and are constructed from a vocabulary of filters and actions.

It integrates with the cloud native serverless capabilities of each provider to provide for real time enforcement of policies with builtin provisioning. Or it can be run as a simple cron job on a server to execute against large existing fleets.

Engineering the Next Generation of Cloud Governance” by @drewfirment


  • Comprehensive support for public cloud services and resources with a rich library of actions and filters to build policies with.
  • Supports arbitrary filtering on resources with nested boolean conditions.
  • Dry run any policy to see what it would do.
  • Automatically provisions serverless functions and event sources ( AWS CloudWatchEvents, AWS Config Rules, Azure EventGrid, GCP AuditLog & Pub/Sub, etc)
  • Cloud provider native metrics outputs on resources that matched a policy
  • Structured outputs into cloud native object storage of which resources matched a policy.
  • Intelligent cache usage to minimize api calls.
  • Supports multi-account/subscription/project usage.
  • Battle-tested - in production on some very large cloud environments.


Quick Install

$ virtualenv --python=python2 custodian
$ source custodian/bin/activate
(custodian) $ pip install c7n


First a policy file needs to be created in YAML format, as an example:

- name: remediate-extant-keys
  description: |
    Scan through all s3 buckets in an account and ensure all objects
    are encrypted (default to AES256).
  resource: aws.s3
    - encrypt-keys

- name: ec2-require-non-public-and-encrypted-volumes
  resource: aws.ec2
  description: |
    Provision a lambda and cloud watch event target
    that looks at all new instances and terminates those with
    unencrypted volumes.
    type: cloudtrail
        - RunInstances
    - type: ebs
      key: Encrypted
      value: false
    - terminate

- name: tag-compliance
  resource: aws.ec2
  description: |
    Schedule a resource that does not meet tag compliance policies
    to be stopped in four days.
    - State.Name: running
    - "tag:Environment": absent
    - "tag:AppId": absent
    - or:
      - "tag:OwnerContact": absent
      - "tag:DeptID": absent
    - type: mark-for-op
      op: stop
      days: 4

Given that, you can run Cloud Custodian with:

# Validate the configuration (note this happens by default on run)
$ custodian validate policy.yml

# Dryrun on the policies (no actions executed) to see what resources
# match each policy.
$ custodian run --dryrun -s out policy.yml

# Run the policy
$ custodian run -s out policy.yml

You can run it with Docker as well

# Download the image
$ docker pull cloudcustodian/c7n

# Run the policy
$ docker run -it \
    -v $(pwd)/output:/output \
    -v $(pwd)/policy.yml:/policy.yml \
    --env-file <(env | grep "^AWS") \
    cloudcustodian/c7n run -v -s /output /policy.yml

Custodian supports a few other useful subcommands and options, including outputs to S3, Cloudwatch metrics, STS role assumption. Policies go together like Lego bricks with actions and filters.

Consult the documentation for additional information, or reach out on gitter.

Get Involved

Additional Tools

The Custodian project also develops and maintains a suite of additional tools here

Multi-account policy execution.
Git history as stream of logical policy changes.
Scale out s3 scanning.
A reference implementation of sending messages to users to notify them.
Cloudtrail indexing and timeseries generation for dashboarding.
Cloud watch log exporting to s3
Indexing of custodian metrics and outputs for dashboarding
Cloudwatch Log parsing for python tracebacks to integrate with


We welcome Your interest in Capital One’s Open Source Projects (the “Project”). Any Contributor to the Project must accept and sign an Agreement indicating agreement to the license terms below. Except for the license granted in this Agreement to Capital One and to recipients of software distributed by Capital One, You reserve all right, title, and interest in and to Your Contributions; this Agreement does not impact Your rights to use Your own Contributions for any other purpose.

Sign the Individual Agreement

Sign the Corporate Agreement

Code of Conduct

This project adheres to the Open Code of Conduct. By participating, you are expected to honor this code.

You can’t perform that action at this time.