Chapter 15. Tips for undercloud and overcloud services

Red Hat OpenStack Platform director uses OpenStack Orchestration (heat) to conduct the main deployment and provisioning functions. Heat uses a series of workers to execute deployment tasks. To calculate the default number of workers, the director heat configuration halves the total CPU thread count of the undercloud. In this instance, thread count refers to the number of CPU cores multiplied by the hyper-threading value. For example, if your undercloud has a CPU with 16 threads, heat spawns 8 workers by default. The director configuration also uses a minimum and maximum cap by default:

However, you can set the number of workers manually with the HeatWorkers parameter in an environment file:

parameter_defaults:
  HeatWorkers: 16

custom_env_files: heat-workers.yaml

If you enabled SSL/TLS in the undercloud (see Section 4.2, “Undercloud configuration parameters”), you might want to harden the SSL/TLS ciphers and rules that are used with the HAProxy configuration. This hardening helps to avoid SSL/TLS vulnerabilities, such as the POODLE vulnerability.

Set the following hieradata using the hieradata_override undercloud configuration option:

For example, you might want to use the following cipher and rules:

Create a hieradata override file (haproxy-hiera-overrides.yaml) with the following content:

tripleo::haproxy::ssl_cipher_suite: ECDHE-ECDSA-CHACHA20-POLY1305:ECDHE-RSA-CHACHA20-POLY1305:ECDHE-ECDSA-AES128-GCM-SHA256:ECDHE-RSA-AES128-GCM-SHA256:ECDHE-ECDSA-AES256-GCM-SHA384:ECDHE-RSA-AES256-GCM-SHA384:DHE-RSA-AES128-GCM-SHA256:DHE-RSA-AES256-GCM-SHA384:ECDHE-ECDSA-AES128-SHA256:ECDHE-RSA-AES128-SHA256:ECDHE-ECDSA-AES128-SHA:ECDHE-RSA-AES256-SHA384:ECDHE-RSA-AES128-SHA:ECDHE-ECDSA-AES256-SHA384:ECDHE-ECDSA-AES256-SHA:ECDHE-RSA-AES256-SHA:DHE-RSA-AES128-SHA256:DHE-RSA-AES128-SHA:DHE-RSA-AES256-SHA256:DHE-RSA-AES256-SHA:ECDHE-ECDSA-DES-CBC3-SHA:ECDHE-RSA-DES-CBC3-SHA:EDH-RSA-DES-CBC3-SHA:AES128-GCM-SHA256:AES256-GCM-SHA384:AES128-SHA256:AES256-SHA256:AES128-SHA:AES256-SHA:DES-CBC3-SHA:!DSS
tripleo::haproxy::ssl_options: no-sslv3 no-tls-tickets

Set the hieradata_override parameter in the undercloud.conf file to use the hieradata override file you created before you ran openstack undercloud install:

[DEFAULT]
...
hieradata_override = haproxy-hiera-overrides.yaml
...