Use the filesystem InSpec resource to audit filesystem disk space usage.



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


This resource first became available in v1.51.0 of InSpec.

The free_kb, size_kb, and type properties became available in v3.6 of InSpec.


Versions of this resource in InSpec prior to 3.5.x offered a property size, which returned a value in GB when on Windows and a value in KB on Linux, though it was documented to always return KB. All new code should use size_kb which is unit-stable. The property size will remain available in InSpec v3 and 4, but will be deprecated in the future.


A filesystem resource block declares tests for disk space in a partition:

describe filesystem('/') do
  its('size_kb') { should be >= 32 * 1024 * 1024}
  its('free_kb') { should be >= 50 * 1024 }
  its('percent_free') { should be >= 20 }
  its('type') { should cmp 'ext4' }


  • filesystem('/') states that the resource will look at the root (/) partition.
  • size_kb is the total partition size and is measured in kilobytes (KB).
  • free_kb is the available space on the partition and is measured in kilobytes (KB).
  • percent_free is the percentage of available free space, and ranges from 0 to 100.

Resource Property Examples

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

Test if the root partition is greater than 32000 KB

describe filesystem('/') do
  its('size_kb') { should be >= 32000 }

Test that the root partition has more than 5GB free

describe filesystem('/') do
  its('free_kb') { should be >= 5000000 }

Test if the C:\ partition is NTFS

describe filesystem('c:\') do
  its('type') { should cmp 'NTFS' }

Test if the /var partition has sufficient free space

describe filesystem('/var') do
  its('percent_free') { should be >= 20 }


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