The OpenShift Origin install method uses Ansible. Ansible is useful for running
parallel operations, meaning a fast and efficient installation. However, these
can be improved upon with additional tuning options.
Parallel behavior can overwhelm a content source, such as your image registry or
Red Hat Satellite server. Preparing your server’s infrastructure pods and
operating system patches can help prevent this issue. See the
Configuring
Ansible section for more information.
Run the installer from the lowest-possible latency control node (LAN speeds).
Running over a wide area network (WAN) is not advised, neither is running the
installation over a lossy network connection.
Ansible provides its own
guidance for
performance and scaling, including using RHEL 6.6 or later to ensure the
version of OpenSSH supports ControlPersist, and running the installer from the
same LAN as the cluster, but not running it from a machine in the cluster.
The following is an example Ansible configuration for large cluster installation
and administration that incorporates the recommendations documented by Ansible:
# cat /etc/ansible/ansible.cfg
# config file for ansible -- http://ansible.com/
# ==============================================
[defaults]
forks = 20 (1)
host_key_checking = False
remote_user = root
roles_path = roles/
gathering = smart
fact_caching = jsonfile
fact_caching_connection = $HOME/ansible/facts
fact_caching_timeout = 600
log_path = $HOME/ansible.log
nocows = 1
callback_whitelist = profile_tasks
[privilege_escalation]
become = False
[ssh_connection]
ssh_args = -o ControlMaster=auto -o ControlPersist=600s
control_path = %(directory)s/%%h-%%r
pipelining = True (2)
timeout = 10
| 1 |
20 forks is ideal, because larger forks can lead to installations failing. |
| 2 |
Pipelining reduces the number of connections between control and target nodes, helping to improve installer performance. |