Cloud Custodian

Cloud Custodian is a rules engine for AWS fleet management. 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 accounts 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, etc) and are constructed from a vocabulary of filters and actions.

It integrates with lambda and cloudwatch events to provide for real time enforcement of policies with builtin provisioning of the lambdas, or as a simple cron job on a server to execute against large existing fleets.

“Engineering the Next Generation of Cloud Governance” by @drewfirment

Features

• Comprehensive support for AWS services and resources (~60), along with ~160 actions and ~180 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 lambda functions, config rules, and cloud watch event targets for real-time policies.
• Cloudwatch metrics outputs on resources that matched a policy
• Structured outputs into s3 of which resources matched a policy.
• Intelligent cache usage to minimize api calls.
• Battle-tested - in production on some very large AWS accounts.
• Supports cross-account usage via STS role assumption.
• Supports integration with custom/user supplied lambdas as actions.

Links

• Homepage
• Docs
• Developer Install

Quick Install

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

(Note that Custodian's Lambda features currently do not work outside of a virtualenv.)

Usage

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

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

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

- name: tag-compliance
  resource: ec2
  description: |
    Schedule a resource that does not meet tag compliance policies
    to be stopped in four days.
  filters:
    - State.Name: running
    - "tag:Environment": absent
    - "tag:AppId": absent
    - or:
      - "tag:OwnerContact": absent
      - "tag:DeptID": absent
  actions:
    - 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 -c policy.yml

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

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

Custodian supports a few other useful subcommands and options, including outputs to s3, cloud watch 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

Mailing List - https://groups.google.com/forum/#!forum/cloud-custodian

Gitter - https://gitter.im/capitalone/cloud-custodian

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