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Securing services with SSL certificates

The OpenStack Security Guide recommends providing secure communication between various services in an OpenStack deployment. The OpenStack-Ansible project currently offers the ability to configure SSL certificates for secure communication between services:

All public endpoints reside behind haproxy, resulting in the only certificate management for externally visible https services are those for haproxy. Certain internal services such as RabbitMQ also require proper SSL configuration.

When deploying with OpenStack-Ansible, you can either use self-signed certificates that are generated during the deployment process or provide SSL certificates, keys, and CA certificates from your own trusted certificate authority. Highly secured environments use trusted, user-provided certificates for as many services as possible.

Note

Perform all SSL certificate configuration in /etc/openstack_deploy/user_variables.yml file. Do not edit the playbooks or roles themselves.

Openstack-Ansible uses an ansible role ansible_role_pki as a general tool to manage and install self-signed and user provided certificates.

Note

The openstack-ansible example configurations are designed to be minimal examples and in test or development use-cases will set external_lb_vip_address to the IP address of the haproxy external endpoint. For a production deployment it is advised to set external_lb_vip_address to be the FQDN which resolves via DNS to the IP of the external endpoint.

Self-signed certificates

Self-signed certificates enable you to start quickly and encrypt data in transit. However, they do not provide a high level of trust for public endpoints in highly secure environments. By default, self-signed certificates are used in OpenStack-Ansible. When self-signed certificates are used, certificate verification is automatically disabled.

Self-signed certificates can play an important role in securing internal services within the Openstack-Ansible deployment, as they can only be issued by the private CA associated with the deployment. Using mutual TLS between backend services such as RabbitMQ and MariaDB with self-signed certificates and a robust CA setup can ensure that only correctly authenticated clients can connect to these internal services.

Generating and regenerating self-signed certificate authorities

A self-signed certificate authority is generated on the deploy host during the first run of the playbook.

To regenerate the certificate authority you must set the openstack_pki_regen_ca variable to either the name of the root CA or intermediate CA you wish or regenerate, or to true to regenerate all self-signed certificate authorities.

# openstack-ansible -e "openstack_pki_regen_ca=ExampleCorpIntermediate" certificate-authority.yml

Take particular care not to regenerate Root or Intermediate certificate authorities in a way that may invalidate existing server certificates in the deployment. It may be preferable to create new Intermediate CA certificates rather than regenerate existing ones in order to maintain existing chains of trust.

Generating and regenerating self-signed certificates

Self-signed certificates are generated for each service during the first run of the playbook.

To regenerate a new self-signed certificate for a service, you must set the <servicename>_pki_regen_cert variable to true in one of the following ways:

• To force a self-signed certificate to regenerate, you can pass the variable to openstack-ansible on the command line:

  # openstack-ansible -e "haproxy_pki_regen_cert=true" haproxy-install.yml
  

• To force a self-signed certificate to regenerate with every playbook run, set the appropriate regeneration option to true. For example, if you have already run the haproxy playbook, but you want to regenerate the self-signed certificate, set the haproxy_pki_regen_cert variable to true in the /etc/openstack_deploy/user_variables.yml file:

  haproxy_pki_regen_cert: true
  

Generating and regenerating self-signed user certificates

Self-signed user certificates are generated but not installed for services outside of Openstack ansible. These user certificates are signed by the same self-signed certificate authority as is used by openstack services but are intended to be used by user applications.

To generate user certificates, define a variable with the prefix user_pki_certificates_ in the /etc/openstack_deploy/user_variables.yml file.

Example

user_pki_certificates_example:
   - name: "example"
     provider: ownca
     cn: "example.com"
     san: "DNS:example.com,IP:x.x.x.x"
     signed_by: "{{ openstack_pki_service_intermediate_cert_name }}"
     key_usage:
       - digitalSignature
       - keyAgreement
     extended_key_usage:
       - serverAuth

Generate the certificate with the following command:

# openstack-ansible certificate-generate.yml

To regenerate a new self-signed certificate for a service, you must set the user_pki_regen_cert variable to true in one of the following ways:

• To force a self-signed certificate to regenerate, you can pass the variable to openstack-ansible on the command line:

  # openstack-ansible -e "user_pki_regen_cert=true" certificate-generate.yml
  

• To force a self-signed certificate to regenerate with every playbook run, set the user_pki_regen_cert variable to true in the /etc/openstack_deploy/user_variables.yml file:

  user_pki_regen_cert: true
  

User-provided certificates

For added trust in highly secure environments, you can provide your own SSL certificates, keys, and CA certificates. Acquiring certificates from a trusted certificate authority is outside the scope of this document, but the Certificate Management section of the Linux Documentation Project explains how to create your own certificate authority and sign certificates.

Use the following process to deploy user-provided SSL certificates in OpenStack-Ansible:

1. Copy your SSL certificate, key, and CA certificate files to the deployment host.

2. Specify the path to your SSL certificate, key, and CA certificate in the /etc/openstack_deploy/user_variables.yml file.

3. Run the playbook for that service.

HAProxy example

The variables to set which provide the path on the deployment node to the certificates for HAProxy configuration are:

haproxy_user_ssl_cert: /etc/openstack_deploy/ssl/example.com.crt
haproxy_user_ssl_key: /etc/openstack_deploy/ssl/example.com.key
haproxy_user_ssl_ca_cert: /etc/openstack_deploy/ssl/ExampleCA.crt

RabbitMQ example

To deploy user-provided certificates for RabbitMQ, copy the certificates to the deployment host, edit the /etc/openstack_deploy/user_variables.yml file and set the following three variables:

rabbitmq_user_ssl_cert:    /etc/openstack_deploy/ssl/example.com.crt
rabbitmq_user_ssl_key:     /etc/openstack_deploy/ssl/example.com.key
rabbitmq_user_ssl_ca_cert: /etc/openstack_deploy/ssl/ExampleCA.crt

Then, run the playbook to apply the certificates:

# openstack-ansible rabbitmq-install.yml

The playbook deploys your user-provided SSL certificate, key, and CA certificate to each RabbitMQ container.

The process is identical for the other services. Replace rabbitmq in the preceding configuration variables with horizon, haproxy, or keystone, and then run the playbook for that service to deploy user-provided certificates to those services.

Certbot certificates

The HAProxy ansible role supports using certbot to automatically deploy trusted SSL certificates for the public endpoint. Each HAProxy server will individually request a SSL certificate using certbot.

Certbot defaults to using LetsEncrypt as the Certificate Authority, other Certificate Authorities can be used by setting the haproxy_ssl_letsencrypt_certbot_server variable in the /etc/openstack_deploy/user_variables.yml file:

haproxy_ssl_letsencrypt_certbot_server: "https://acme-staging-v02.api.letsencrypt.org/directory"

The http-01 type challenge is used by certbot to deploy certificates so it is required that the public endpoint is accessible directly by the Certificate Authority.

Deployment of certificates using LetsEncrypt has been validated for openstack-ansible using Ubuntu Focal. Other distributions should work but are not tested.

To deploy certificates with certbot, add the following to /etc/openstack_deploy/user_variables.yml to enable the certbot function in the haproxy ansible role, and to create a new backend service called certbot to service http-01 challenge requests.

haproxy_ssl: true
haproxy_ssl_letsencrypt_enable: True
haproxy_ssl_letsencrypt_install_method: "distro"
haproxy_ssl_letsencrypt_email: "email.address@example.com"

If you don’t have horizon deployed, you will need to define dummy service that will listen on 80 and 443 ports and will be used for acme-challenge, whose backend is certbot on the haproxy host:

haproxy_extra_services:
  # the external facing service which serves the apache test site, with a acl for LE requests
  - service:
      haproxy_service_name: certbot
      haproxy_redirect_http_port: 80                         #redirect port 80 to port ssl
      haproxy_redirect_scheme: "https if !{ ssl_fc } !{ path_beg /.well-known/acme-challenge/ }"   #redirect all non-ssl traffic to ssl except acme-challenge
      haproxy_port: 443
      haproxy_frontend_acls: "{{ haproxy_ssl_letsencrypt_acl }}"       #use a frontend ACL specify the backend to use for acme-challenge
      haproxy_ssl: True
      haproxy_backend_nodes:                                 #apache is running on locally on 127.0.0.1:80 serving a dummy site
        - name: local-test-service
          ip_addr: 127.0.0.1
      haproxy_balance_type: http
      haproxy_backend_port: 80
      haproxy_backend_options:
        - "httpchk HEAD /"                                   # request to use for health check for the example service

TLS for Haproxy Internal VIP

As well as load balancing public endpoints, haproxy is also used to load balance internal connections.

By default, OpenStack-Ansible does not secure connections to the internal VIP. To enable this you must set the following variables in the /etc/openstack_deploy/user_variables.yml file:

openstack_service_adminuri_proto: https
openstack_service_internaluri_proto: https

haproxy_ssl_all_vips: true

Run all playbooks to configure haproxy and openstack services.

When enabled haproxy will use the same TLS certificate on all interfaces (internal and external). It is not currently possible in OpenStack-Ansible to use different self-signed or user-provided TLS certificates on different haproxy interfaces.

The only way to use a different TLS certificates on the internal and external VIP is to use certbot.

Enabling TLS on the internal VIP for existing deployments will cause some downtime, this is because haproxy only listens on a single well known port for each OpenStack service and OpenStack services are configured to use http or https. This means once haproxy is updated to only accept HTTPS connections, the OpenStack services will stop working until they are updated to use HTTPS.

For this reason it is recommended that TLS for haproxy internal VIP on existing deployments is deployed at the same time as enabling TLS for Haproxy backends, as this may also cause downtime. For new deployments this should be enabled from the start.

TLS for Haproxy Backends

Securing the internal communications from haproxy to backend services is currently work in progress.

TLS for Live Migrations

Live migration of VM’s using SSH is deprecated and the OpenStack Nova Docs recommends using the more secure native TLS method supported by QEMU. The default live migration method used by OpenStack-Ansible has been updated to use TLS migrations.

QEMU-native TLS requires all compute hosts to accept TCP connections on port 16514 and port range 49152 to 49261.

It is not possible to have a mixed estate of some compute nodes using SSH and some using TLS for live migrations, as this would prevent live migrations between the compute nodes.

There are no issues enabling TLS live migration during an OpenStack upgrade, as long as you do not need to live migrate instances during the upgrade. If you you need to live migrate instances during an upgrade, enable TLS live migrations before or after the upgrade.

To force the use of SSH instead of TLS for live migrations you must set the nova_libvirtd_listen_tls variable to 0 in the /etc/openstack_deploy/user_variables.yml file:

nova_libvirtd_listen_tls: 0

TLS for VNC

When using VNC for console access there are 3 connections to secure, client to haproxy, haproxy to noVNC Proxy and noVNC Proxy to Compute nodes. The OpenStack Nova Docs for remote console access cover console security in much more detail.

In OpenStack-Ansible TLS to haproxy is configured in haproxy, TLS from haproxy to noVNC is not currently enabled and TLS from nVNC to Compute nodes is enabled by default.

Changes will not apply to any existing running guests on the compute node, so this configuration should be done before launching any instances. For existing deployments it is recommended that you migrate instances off the compute node before enabling.

To help with the transition from unencrypted VNC to VeNCrypt, initially noVNC proxy auth scheme allows for both encrypted and unencrypted sessions using the variable nova_vencrypt_auth_scheme. This will be restricted to VeNCrypt only in future versions of OpenStack-Ansible.

nova_vencrypt_auth_scheme: "vencrypt,none"

To not encrypt data from noVNC proxy to Compute nodes you must set the nova_qemu_vnc_tls variable to 0 in the /etc/openstack_deploy/user_variables.yml file:

nova_qemu_vnc_tls: 0