aws.subnet

Filters

• config-compliance

• event

• finding

• flow-logs

• ip-address-usage

• json-diff

• list-item

• marked-for-op

• ops-item

• reduce

• tag-count

• value

• vpc

• vpc-endpoint

ip-address-usage

Filter subnets based on available IP addresses.

example:

Show subnets with no addresses in use.

policies:
  - name: empty-subnets
    resource: aws.subnet
    filters:
      - type: ip-address-usage
        key: NumberUsed
        value: 0

example:

Show subnets where 90% or more addresses are in use.

policies:
  - name: almost-full-subnets
    resource: aws.subnet
    filters:
      - type: ip-address-usage
        key: PercentUsed
        op: greater-than
        value: 90

This filter allows key to be:

• MaxAvailable: the number of addresses available based on a subnet’s CIDR block size (minus the 5 addresses reserved by AWS)

• NumberUsed: MaxAvailable minus the subnet’s AvailableIpAddressCount value

• PercentUsed: NumberUsed divided by MaxAvailable

properties:
  default:
    type: object
  key:
    enum:
    - MaxAvailable
    - NumberUsed
    - PercentUsed
  op:
    enum:
    - eq
    - equal
    - ne
    - not-equal
    - gt
    - greater-than
    - ge
    - gte
    - le
    - lte
    - lt
    - less-than
    - glob
    - regex
    - regex-case
    - in
    - ni
    - not-in
    - contains
    - difference
    - intersect
  type:
    enum:
    - ip-address-usage
  value:
    oneOf:
    - type: array
    - type: string
    - type: boolean
    - type: number
    - type: 'null'
  value_from:
    additionalProperties: 'False'
    properties:
      expr:
        oneOf:
        - type: integer
        - type: string
      format:
        enum:
        - csv
        - json
        - txt
        - csv2dict
      headers:
        patternProperties:
          ? ''
          : type: string
        type: object
      url:
        type: string
    required:
    - url
    type: object
  value_path:
    type: string
  value_regex:
    type: string
  value_type:
    enum:
    - age
    - integer
    - expiration
    - normalize
    - size
    - cidr
    - cidr_size
    - swap
    - resource_count
    - expr
    - unique_size
    - date
    - version
    - float
required:
- type

json-diff

Compute the diff from the current resource to a previous version.

A resource matches the filter if a diff exists between the current resource and the selected revision.

Utilizes config as a resource revision database.

Revisions can be selected by date, against the previous version, and against a locked version (requires use of is-locked filter).

properties:
  selector:
    enum:
    - previous
    - date
    - locked
  selector_value:
    type: string
  type:
    enum:
    - json-diff
required:
- type

Permissions - config:GetResourceConfigHistory

vpc-endpoint

Filters subnets based on their vpc-endpoints

example:

policies:
  - name: athena-endpoint-enabled
    resource: subnet
    filters:
      - type: vpc-endpoint
        key: ServiceName
        value: com.amazonaws.us-east-1.athena

properties:
  default:
    type: object
  key:
    type: string
  op:
    enum:
    - eq
    - equal
    - ne
    - not-equal
    - gt
    - greater-than
    - ge
    - gte
    - le
    - lte
    - lt
    - less-than
    - glob
    - regex
    - regex-case
    - in
    - ni
    - not-in
    - contains
    - difference
    - intersect
  type:
    enum:
    - vpc-endpoint
  value:
    oneOf:
    - type: array
    - type: string
    - type: boolean
    - type: number
    - type: 'null'
  value_from:
    additionalProperties: 'False'
    properties:
      expr:
        oneOf:
        - type: integer
        - type: string
      format:
        enum:
        - csv
        - json
        - txt
        - csv2dict
      headers:
        patternProperties:
          ? ''
          : type: string
        type: object
      url:
        type: string
    required:
    - url
    type: object
  value_path:
    type: string
  value_regex:
    type: string
  value_type:
    enum:
    - age
    - integer
    - expiration
    - normalize
    - size
    - cidr
    - cidr_size
    - swap
    - resource_count
    - expr
    - unique_size
    - date
    - version
    - float
required:
- type

Permissions - ec2:DescribeVpcEndpoints

Actions

• auto-tag-user

• copy-related-tag

• invoke-lambda

• invoke-sfn

• mark-for-op

• modify

• normalize-tag

• notify

• post-finding

• post-item

• put-metric

• remove-tag

• rename-tag

• set-flow-log

• tag

• tag-trim

• webhook

modify

Modify subnet attributes.

example:

policies:
  - name: turn-on-public-ip-protection
    resource: aws.subnet
    filters:
      - type: value
        key: "MapPublicIpOnLaunch.enabled"
        value: false
    actions:
      - type: modify
        MapPublicIpOnLaunch: false

properties:
  AssignIpv6AddressOnCreation:
    type: boolean
  CustomerOwnedIpv4Pool:
    type: string
  DisableLniAtDeviceIndex:
    type: boolean
  EnableDns64:
    type: boolean
  EnableLniAtDeviceIndex:
    type: integer
  EnableResourceNameDnsAAAARecordOnLaunch:
    type: boolean
  EnableResourceNameDnsARecordOnLaunch:
    type: boolean
  MapCustomerOwnedIpOnLaunch:
    type: boolean
  MapPublicIpOnLaunch:
    type: boolean
  PrivateDnsHostnameTypeOnLaunch:
    enum:
    - ip-name
    - resource-name
    type: string
  type:
    enum:
    - modify
required:
- type

Permissions - ec2:ModifySubnetAttribute

set-flow-log

Set flow logs for a network resource

example:

policies:
  - name: vpc-enable-flow-logs
    resource: vpc
    filters:
      - type: flow-logs
        enabled: false
    actions:
      - type: set-flow-log
        attrs:
          DeliverLogsPermissionArn: arn:iam:role
          LogGroupName: /custodian/vpc/flowlogs/

attrs are passed through to create_flow_log and are per the api documentation

https://boto3.amazonaws.com/v1/documentation/api/latest/reference/services/ec2/client/create_flow_logs.html

properties:
  DeliverLogsPermissionArn:
    type: string
  LogDestination:
    type: string
  LogDestinationType:
    enum:
    - s3
    - cloud-watch-logs
  LogFormat:
    type: string
  LogGroupName:
    type: string
  MaxAggregationInterval:
    type: integer
  TrafficType:
    enum:
    - ACCEPT
    - REJECT
    - ALL
    type: string
  attrs:
    type: object
  state:
    type: boolean
  type:
    enum:
    - set-flow-log
required:
- type

Permissions - ec2:CreateFlowLogs, logs:CreateLogGroup