openstack-ansible/doc/source/user/security/ssl-certificates.rst

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.

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 generate 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 create 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

To generate 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.

LetsEncrypt certificates

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

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

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

To deploy certificates with LetsEncrypt, add the following to /etc/openstack_deploy/user_variables.yml to enable the letsencrypt function in the haproxy ansible role, and to create a new backend service called letsencrypt 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