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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 most environments need are those for haproxy.

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.

참고

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

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 highly secure environments. By default, self-signed certificates are used in OpenStack-Ansible. When self-signed certificates are used, certificate verification is automatically disabled.

Setting subject data for self-signed certificates

Change the subject data of any self-signed certificate by using configuration variables. The configuration variable for each service is formatted as <servicename>_ssl_self_signed_subject. For example, to change the SSL certificate subject data for HAProxy, adjust the /etc/openstack_deploy/user_variables.yml file as follows:

haproxy_ssl_self_signed_subject: "/C=US/ST=Texas/L=San Antonio/O=IT/CN=haproxy.example.com"

For more information about the available fields in the certificate subject, see the OpenSSL documentation for the req subcommand.

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>_ssl_self_signed_regen 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 "horizon_ssl_self_signed_regen=true" os-horizon-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_ssl_self_signed_regen variable to true in the /etc/openstack_deploy/user_variables.yml file:

    haproxy_ssl_self_signed_regen: true

참고

Regenerating self-signed certificates replaces the existing certificates whether they are self-signed or user-provided.

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_setup_extra_params: "--http-01-address {{ ansible_host }} --http-01-port 8888"
haproxy_ssl_letsencrypt_email: "email.address@example.com"

haproxy_extra_services:
  # an internal only service for acme-challenge whose backend is certbot running on any haproxy instance
  - service:
      haproxy_service_name: letsencrypt
      haproxy_backend_nodes: "{{ groups['haproxy_all'] }}"
      backend_rise: 1                       #rise quickly to detect certbot running without delay
      backend_fall: 2
      haproxy_bind:
        - 127.0.0.1                         #bind to the localhost as the host internal IP will be used by certbot
      haproxy_port: 8888
      haproxy_balance_type: http

Copy the whole variable haproxy_default_services from /opt/openstack-ansible/inventory/group_vars/haproxy/haproxy.yml to /etc/openstack_deploy/group_vars/haproxy/haproxy_all.yml and update the section for horizon to include the ACL redirects http-01 challenges to the HAProxy letsencrypt backend as follows:

- service:
    haproxy_service_name: horizon
    haproxy_backend_nodes: "{{ groups['horizon_all'] | default([]) }}"
    haproxy_ssl: "{{ haproxy_ssl }}"
    haproxy_ssl_all_vips: true
    haproxy_port: "{{ haproxy_ssl | ternary(443,80) }}"
    haproxy_backend_port: 80
    haproxy_redirect_http_port: 80
    haproxy_balance_type: http
    haproxy_balance_alg: source
    haproxy_backend_options:
      - "httpchk HEAD / HTTP/1.0\\r\\nUser-agent:\\ osa-haproxy-healthcheck"
    haproxy_service_enabled: "{{ groups['horizon_all'] is defined and groups['horizon_all'] | length > 0 }}"
    haproxy_redirect_scheme: "https if !{ ssl_fc } !{ path_beg /.well-known/acme-challenge/ }"   #redirect all non-ssl traffic to ssl except acme-challenge
    haproxy_frontend_acls:                                 #use a frontend ACL specify the backend to use for acme-challenge
      letsencrypt-acl:
          rule: "path_beg /.well-known/acme-challenge/"
          backend_name: letsencrypt