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STIG-Partitioned Enterprise Linux (spel) is a project that helps create and publish Enterprise Linux images that are partitioned according to the DISA STIG. The resulting images also use LVM to simplify volume management. The images are configured with help from the scripts and packages in the AMIgen7, and Lx-GetAMI-Utils projects.

Why spel

VMs' root filesystems are generally not live-repartitionable once launced from their images. As a result, if a STIG-scan is performed against most of the community-published images for Red Hat and CentOS, those scans will note failures for each of the various "${DIRECTORY} is on its own filesystem" tests. The images produced through this project are designed to ensure that these particular scan-failures do not occur.

Aside from addressing the previously-noted partitioning findings, spel does not apply any STIG-related hardening. The spel-produced images are expected to act as a better starting-point in a larger hardening process.

If your organization does not already have an automated hardening process, please see our tool, Watchmaker. This tool is meant to help spel-users (and users of other Enterprise Linux images) by performing launch-time hardening activities.

We have a FAQ now!

We've added an FAQ to the project. Hopefully, your questions are answered there. If they aren't, please feel free to submit an issue requesting an appropriate FAQ entry.

Current Published Images

SPEL AMIs are published monthly. The AMI table below contains links to the AWS Console that search by AMI Name and sort the result by creation date. The most recent AMI of each build will be at the top when viewed in the AWS Console.

RPM Manifests for published images are available in the manifests directory.

AWS Region Builder Name / Link
us-east-1 spel-minimal-rhel-7-hvm
us-east-2 spel-minimal-rhel-7-hvm
us-west-1 spel-minimal-rhel-7-hvm
us-west-2 spel-minimal-rhel-7-hvm
us-gov-west-1 spel-minimal-rhel-7-hvm
Vagrant Cloud Name Vagrant Provider
plus3it/spel-minimal-centos-7 virtualbox

Deprecated EL6 Images

The AMI table below contains links to EL6 images that have been deprecated. These images are no longer being generated on a monthly base. The last published AMI of each build will be at the top when viewed in the AWS Console.

The last version for these EL6 builds was 2018.10.1. To build any them, or to view the manifests, checkout that version of this project.

These EL6 images were created with the help of the AMIgen6 project.

AWS Region Builder Name / Link
us-east-1 spel-minimal-rhel-6-hvm
us-east-2 spel-minimal-rhel-6-hvm
us-west-1 spel-minimal-rhel-6-hvm
us-west-2 spel-minimal-rhel-6-hvm
us-gov-west-1 spel-minimal-rhel-6-hvm
Vagrant Cloud Name Vagrant Provider
plus3it/spel-minimal-centos-6 virtualbox

Default username

The default username for all spel images is maintuser.

If you wish to change the default username at launch, you can do so via cloud-init with userdata something like the following. Change <USERNAME> to your desired value.

    name: <USERNAME>
    gecos: spel default user
    lock_passwd: true
    sudo: ["ALL=(root) NOPASSWD:ALL"]


Packer by Hashicorp is used to manage the process of building images.

  1. Download and extract packer for your platform. Add it to your PATH, if you like. On Linux, watch out for other packer executables with the same name...

  2. If building the AMIs for Amazon Web Services, ensure your AWS credentials are configured. You do not really need the aws cli utility, but it is a convenient way to configure the credential file. You can also export the environment variables. Or, if running packer in an EC2 instance, an instance role with the requisite permissions will also work. See the packer docs for details on the necessary permissions.

    NOTE: No packer templates in this project will contain variables for AWS credentials; this is intentional, to avoid mistakes where credentials get committed to the repository. Instead, packer knows to read the credentials from the credential file or from the environment variables, or to retrieve them from the instance role. See the docs.

  3. If building VirtualBox image(s), you will need to install VirtualBox and Vagrant.

  4. If building VMware image(s), depending on your platform, you will need to install either VMware Fusion, VMware Workstation Pro, or VMware Player. For all platforms, you will also need Vagrant.

  5. The template(s) push the Vagrant boxes for the VirtualBox and VMware images to Hashicorp Vagrant Cloud, which requires a Vagrant Cloud account.

  6. If building a VHD or Image for Azure, ensure you have authorized access to ARM. The creation of destination objects and a Service Principal can either be done manually or via script. If not building in Public region, use of device login is not possible and a Service Principal is required.


NOTE: In all steps below, the examples use syntax that works on Linux. If you are running packer from a Windows system, simply use the appropriate syntax for the relative path to the packer template. Most important, for Windows, use .\ preceding the path to the template. E.g. .\spel\minimal-linux.json.

  1. Clone the repository:

    git clone && cd spel
  2. Validate the template (Optional):

    packer validate spel/minimal-linux.json
  3. Begin the build. This requires at least two variables, spel_identifier and spel_version. See the section Packer Variables for more details.

    NOTE: This will build images for all the builders defined in the template. Use packer build --help to see how to restrict the build to to a subset of the builders.

    packer build \
        -var 'vagrantcloud_username=myvagrantclouduser' \
        -var 'spel_identifier=unique-project-id' \
        -var 'spel_version=0.0.1' \

    If building the VirtualBox or VMware images for use with Vagrant, the template is configured to host the resulting images with Hashicorp Vagrant Cloud. This requires passing the variable vagrantcloud and exporting the environment variable VAGRANTCLOUD_TOKEN.

Minimal Linux Packer Template

The Minimal Linux template builds STIG-partitioned images with a set of packages that correspond to the "Minimal" install option in Anaconda. Further, the AWS images include a handful of additional packages that are intended to increase functionality in EC2 and make the images more comparable with Amazon Linux.

  • Template Path: spel/minimal-linux.json

Minimal Linux Packer Variables

The Minimal Linux packer template supports the following user variables (and defaults):

"variables": {
    "ami_force_deregister": "false",
    "ami_groups": "",
    "ami_regions": "",
    "ami_users": "",
    "aws_ec2_instance_type": "t2.xlarge",
    "aws_region": "us-east-1",
    "azure_client_id": "{{env `ARM_CLIENT_ID`}}",
    "azure_client_secret": "{{env `ARM_CLIENT_SECRET`}}",
    "azure_dest_resource_group": "",
    "azure_dest_storage_account": "",
    "azure_environment": "",
    "azure_execute_using_public_ip": "",
    "azure_location": "",
    "azure_source_image_centos7": "",
    "azure_source_image_resource_group_centos7": "",
    "azure_source_vhd_centos7": "",
    "azure_subnet_name": "",
    "azure_subscription_id": "{{env `ARM_SUBSCRIPTION_ID`}}",
    "azure_virtual_network_name": "",
    "azure_vm_size": "Standard_DS2_v2",
    "iso_url_centos7": "",
    "root_volume_size": "20",
    "security_group_cidrs": "",
    "source_ami_centos7_hvm": "ami-090b9dabe1c9f40b3",
    "source_ami_rhel7_hvm": "ami-0394fe9914b475c53",
    "spel_amigen7branch": "master",
    "spel_amigen7source": "",
    "spel_amigen7storlay": "/:rootVol:4,swap:swapVol:2,/home:homeVol:1,/var:varVol:2,/var/log:logVol:2,/var/log/audit:auditVol:100%FREE",
    "spel_amiutilsource": "",
    "spel_awsclisource": "",
    "spel_customreponame7": "",
    "spel_customreporpm7": "",
    "spel_desc_url": "",
    "spel_disablefips": "",
    "spel_epel7release": "",
    "spel_epelrepo": "epel",
    "spel_extrarpms": ",python36",
    "spel_identifier": "",
    "spel_version": "",
    "ssh_interface": "public_dns",
    "subnet_id": "",
    "vagrantcloud_token": "{{env `VAGRANTCLOUD_TOKEN`}}",
    "vagrantcloud_username": ""
Variable Name Description
root_volume_size Size (in GiB) of image root volume
vagrantcloud_username Username in Hashicorp Vagrant Cloud
vagrantcloud_token Authentication token for Vagrant Cloud (env: VAGRANTCLOUD_TOKEN)
security_group_cidrs CIDRs to restrict security group created by Packer
spel_identifier Project ID to associate to the resulting images
spel_version Version to assign to the resulting image(s)
spel_amigen7source URL to the git repository for the AMIGen7 project
spel_amigen7branch Name of branch within the spel_amigen7source to use
spel_amigen7storlay List of MOUNT:VOLNAME:VOLSIZE tuples to customize storage-layout
spel_amiutilsource URL to the git repository for the Lx-GetAMI-Utils project
spel_awsclisource URL to the site hosting the file
spel_customreporpm7 URL to a custom release RPM containing base repos for EL7
spel_customreponame7 Name(s) of the custom yum repos (* or comma-separated) for EL7
spel_disablefips Flag that disables FIPS in EL7 AMIs
spel_desc_url URL to detailed description of AMI
spel_devnode Override device-path for the bootstrap-host's boot disk
spel_epel7release URL to the release RPM for the EPEL 7 repo
spel_epelrepo Name of the epel repo (if different than "epel")
spel_extrarpms Comma-separated list of extra package/@group names to pass to yum

For more details on the syntax for spel_amigen7storlay, refer to the AMIgen doc on custom partitioning.

All other variables in the packer template map directly to variables defined in the packer docs for the amazon-ebs builder or the virtualbox-iso builder or the vmware-iso builder.

Minimal Linux Packer Builders

The Minimal Linux packer template includes the following builders:

Builder Name Description
minimal-centos-7-hvm amazon-ebs builder that results in a minimal CentOS 7 HVM AMI
minimal-rhel-7-hvm amazon-ebs builder that results in a minimal RHEL 7 HVM AMI
minimal-centos-7-azure-vhd azure-arm builder that results in a minimal CentOS 7 VHD
minimal-centos-7-azure-image azure-arm builder that results in a minimal CentOS 7 Image
minimal-centos-7-openstack-image openstack builder that results in a minimal CentOS 7 Image

Minimal Linux Packer Post-Provisioners

The Minimal Linux packer template includes the following post-provisioners:

  • vagrant: The vagrant post-provisioner creates vagrant boxes from on the virtualbox and vmware images.

  • vagrant-cloud: The vagrant-cloud post-provisioners upload the vagrant boxes to Hashicorp Vagrant Cloud.

Building for the AWS US GovCloud Region

To build images for the AWS US GovCloud region, us-gov-west-1, it is necessary to pass several variables that are specific to the region. The AMIs below have been tested and/or created in us-gov-west-1 to work with the spel template(s). Also, the builders should be restricted so as not to build the Vagrant images.

packer build \
    -var 'spel_identifier=unique-project-id' \
    -var 'spel_version=0.0.1' \
    -var 'aws_region=us-gov-west-1' \
    -var 'source_ami_centos7_hvm=ami-faae349b' \
    -var 'source_ami_rhel7_hvm=ami-91d649f0' \
    -only 'minimal-centos-7-hvm,minimal-rhel-7-hvm' \

Building for Microsoft Azure

Azure regions may not all support Azure Managed Disks and in turn managed VM images. Packer provides capabilities within the Azure Resource Manager Builder for creating either a VHD or Image.

A source VHD URI or source Image Name and Resource Group is required from which to start the SPEL Azure build. Available Azure Marketplace CentOS Images do not currently contain or execute cloud-init, so a custom VHD or source image of your own, configured with cloud-init, is needed.

The resultant SPEL VHD or Image will be configured to use the Azure Linux agent, WALinuxAgent per recommended configurations. Currently, the use of cloud-init exclusively does not enable execution/installation of Azure VM Extensions. The below variables also disable FIPS mode in the resultant SPEL VHD or Image. Currently the Azure Linux agent does not support FIPS mode when utilizing Azure VM Extensions. If no plans exist to utilize Azure VM Extensions on VMs provisioned from SPEL VHDs or Images, FIPS mode can be enabled, but the waagent configuration must also be modified accordingly.

The variables referenced in the packer builds below should be modified with appropriate parameters for your environment. Any content between and including the < and > characters should be replaced.

export ARM_SUBSCRIPTION_ID=<xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx>
export ARM_CLIENT_ID=<xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx>
export ARM_CLIENT_SECRET=<YourServicePrincipalSecret>

Building an Azure VHD When building a SPEL VHD, the source and destination storage account must be the same. Resultant VHD naming is limited, the combination of spel_identifier and spel_version must be less than 23 characters.

packer build \
    -var 'spel_identifier=unique-project-id' \
    -var 'spel_version=0.0.1' \
    -var 'spel_disablefips=true' \
    -var 'spel_extrarpms=WALinuxAgent' \
    -var 'azure_location=<azure datacenter>' \
    -var 'azure_environment=<Public or USGovernment>' \
    -var 'azure_source_vhd_centos7=https://<storageacctname>.blob.core.<corresponding azure env>.net/<container>/<vhdname>.vhd' \
    -var 'azure_dest_resource_group=<resource group short name>' \
    -var 'azure_dest_storage_account=<storage account short name>' \
    -only 'minimal-centos-7-azure-vhd' \

Building an Azure Image

packer build \
    -var 'spel_identifier=unique-project-id' \
    -var 'spel_version=0.0.1' \
    -var 'spel_disablefips=true' \
    -var 'spel_extrarpms=WALinuxAgent' \
    -var 'azure_location=<azure datacenter>' \
    -var 'azure_environment=<Public or USGovernment>' \
    -var 'azure_source_image_resource_group_centos7=<resource group short name>' \
    -var 'azure_source_image_centos7=<image short name>' \
    -var 'azure_dest_resource_group=<resource group short name>' \
    -only 'minimal-centos-7-azure-image' \

Building for OpenStack

To build images for an OpenStack environment, it is necessary to pass several variables that are specific to the environment. The CentOS 7 Generic Cloud image has been tested to work with the spel template(s). Also, the builders should be restricted so as not to build the Vagrant images.

packer build \
    -var 'openstack_allow_insecure_connection=false' \
    -var 'openstack_flavor_name=your_flavor_name_for_temporary_instance' \
    -var 'openstack_floating_ip_network_name=your_provider_network_name' \
    -var 'openstack_network_ids=your_network_id_for_temporary_instance,second_network_id,etc.' \
    -var 'openstack_security_group_names=your_security_group_name_for_temporary_instance,second_sg_name,etc.' \
    -var 'openstack_source_image_name=your_source_image_name' \
    -var 'spel_identifier=spel' \
    -only 'minimal-centos-7-openstack-image' \

For expected values, see links below:

Testing With AMIgen7

The spel automation leverages the AMIgen7 project as a build-helper for creation of Amazon Machine Images. Due to the closely-coupled nature of the two projects, it's recommended that any changes made to AMIgen7 be tested with spel prior to merging changes to AMIgen7's master branch.

To facilitate this testing, the runtime-variable spel_amigen7branch was added to spel. Using this runtime-variable, in combination with the spel_amigen7source runtime-variable, allows one to point spel to a fork/branch of AMIgen7 during a integration-test build. To test, update your packer invocation by adding elements like:

packer build \
   -var 'spel_amigen7source=<FORK_USER>/AMIgen7.git' \
   -var 'spel_amigen7branch=IssueNN' \

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