aws_subnets

Use the aws_subnets InSpec audit resource to test properties of some or all subnets.

Subnets are networks within a VPC that can have their own block of IP address’s and ACL’s. VPCs span across all availability zones in AWS, while a subnet in a VPC can only span a single availability zone. Separating IP addresses allows for protection if there is a failure in one availability zone.


Availability

Installation

This resource is distributed along with InSpec itself. You can use it automatically.

Version

This resource first became available in v2.0.16 of InSpec.

Syntax

An aws_subnets resource block uses an optional filter to select a group of subnets and then tests that group.

# Test all subnets within a single vpc
describe aws_subnets.where(vpc_id: 'vpc-12345678') do
  its('subnet_ids') { should include 'subnet-12345678' }
  its('subnet_ids') { should include 'subnet-98765432' }
end


Examples

The following examples show how to use this InSpec audit resource.

As this is the initial release of aws_subnets, its limited functionality precludes examples.


Filter Criteria

  • vpc_id, subnet_id

Filter Examples

vpc_id

A string identifying the VPC which may or may not contain subnets.

# Look for all subnets within a vpc.
describe aws_subnets.where( vpc_id: 'vpc-12345678') do
  its('subnet_ids') { should include 'subnet-12345678' }
  its('subnet_ids') { should include 'subnet-98765432' }
end

subnet_id

A string identifying a specific subnet.

# Examine a specific subnet
describe aws_subnets.where(subnet_id: 'subnet-12345678') do
  its('cidr_blocks') { should eq ['10.0.1.0/24'] }
end


Properties

  • cidr_blocks, states, subnet_ids,vpc_ids


Property Examples

cidr_blocks

Provides a string that contains the cidr block of ip addresses that can be given in the subnet.

# Examine a specific subnets cidr_blocks
describe aws_subnets.where( subnet_id: 'subnet-12345678') do
  its('cidr_blocks') { should eq ['10.0.1.0/24'] }
end

states

Provides an array of strings including if the subnets are available.

# Examine a specific vpcs Subnet IDs
describe aws_subnets.where( vpc_id: 'vpc-12345678') do
  its('states') { should_not include 'pending' }
end

subnet_ids

Provides an array of strings containing the subnet IDs associated with a vpc.

# Examine a specific vpcs Subnet IDs
describe aws_subnets.where( vpc_id: 'vpc-12345678') do
  its('subnet_ids') { should include 'subnet-12345678' }
  its('subnet_ids') { should include 'subnet-98765432' }
end

vpc_ids

Provides an array containing a string of the vpc_id associated with a subnet.

# Examine a specific subnets VPC IDS
describe aws_subnets.where( subnet_id: 'subnet-12345678') do
  its('vpc_ids') { should include 'vpc-12345678' }
end


Matchers

For a full list of available matchers, please visit our matchers page.

exists

The control will pass if the filter returns at least one result. Use should_not if you expect zero matches.

# You dont always have subnets, so you can test if there are any.
describe aws_subnets
  it { should exist }
end

# Test that there are subnets in a vpc
describe aws_subnets.where(vpc_id: 'vpc-12345678')
  it { should exist }
end

AWS Permissions

Your Principal will need the ec2:DescribeSubnets action with Effect set to Allow.

You can find detailed documentation at Actions, Resources, and Condition Keys for Amazon EC2.