anchor.diff:  SDN].
   ====
   
  -The following sections describe example *_/etc/ansible/hosts_* files for various environment
  -topographies, including example configurations for
  -link:../../architecture/infrastructure_components/kubernetes_infrastructure.html#high-availability-masters[using multiple
  -masters for high availability]. You can choose an example that matches your
  -requirements and use as your inventory file when
  -link:#running-the-ansible-installer[running the Ansible installer], or modify an example to match your own environment.
  +[[configuring-host-variables]]
  +
  +*Configuring Host Variables*
  +
  +To assign environment variables to hosts during the Ansible install, indicate
  +the desired variables in the *_/etc/ansible/hosts_* file after the host entry in
  +the *[masters]* or *[nodes]* sections. For example:
  +
  +====
  +----
  +[masters]
  +ec2-52-6-179-239.compute-1.amazonaws.com openshift_public_hostname=ose3-master.public.example.com
  +----
  +====
  +
  +The following table describes variables for use with the Ansible installer that
  +can be assigned to individual host entries:
  +
  +.Host Variables
  +[options="header"]
  +|===
  +
  +|Variable |Purpose
  +
  +|`*openshift_hostname*`
  +|This variable overrides the internal cluster host name for the system. Use this
  +when the system's default IP address does not resolve to the system host name.
  +
  +|`*openshift_public_hostname*`
  +|This variable overrides the system's public host name. Use this for cloud
  +installations, or for hosts on networks using a network address translation
  +(NAT).
  +
  +|`*openshift_ip*`
  +|This variable overrides the cluster internal IP address for the system. Use
  +this when using an interface that is not configured with the default route.
  +
  +|`*openshift_public_ip*`
  +|This variable overrides the system's public IP address. Use this for cloud
  +installations, or for hosts on networks using a network address translation
  +(NAT).
  +|===
  +
  +[[configuring-cluster-variables]]
  +
  +*Configuring Cluster Variables*
  +
  +To assign environment variables during the Ansible install that apply more
  +globally to your OpenShift cluster overall, indicate the desired variables in
  +the *_/etc/ansible/hosts_* file on separate, single lines within the *[OSEv3:vars]*
  +section. For example:
  +
  +====
  +----
  +[OSEv3:vars]
  +
  +openshift_master_identity_providers=[{'name': 'htpasswd_auth', 'login': 'true', 'challenge': 'true', 'kind': 'HTPasswdPasswordIdentityProvider', 'filename': '/etc/openshift/openshift-passwd'}]
  +
  +osm_default_subdomain=apps.test.example.com
  +----
  +====
  +
  +The following table describes variables for use with the Ansible installer that
  +can be assigned cluster-wide:
  +
  +.Cluster Variables
  +[options="header", cols="1,2"]
  +|===
  +
  +|Variable |Purpose
  +
  +|`*ansible_ssh_user*`
  +|This variable sets the SSH user for the installer to use and defaults to
  +*root*. This user should allow SSH-based authentication
  +link:prerequisites.html#ensuring-host-access[without requiring a password]. If
  +using SSH key-based authentication, then the key should be managed by an SSH
  +agent.
  +
  +|`*ansible_sudo*`
  +|If `*ansible_ssh_user*` is not *root*, this variable must be set to *true* and
  +the user must be configured for passwordless *sudo*.
  +
  +|`*openshift_master_cluster_hostname*`
  +|This variable overrides the host name for the cluster, which defaults to the
  +host name of the master.
  +
  +|`*openshift_master_cluster_public_hostname*`
  +|This variable overrides the public host name for the cluster, which defaults to
  +the host name of the master.
  +
  +|`*openshift_master_identity_providers*`
  +|This variable overrides the link:../configuring_authentication.html[identity
  +provider], which defaults to
  +link:../configuring_authentication.html#DenyAllPasswordIdentityProvider[Deny
  +All].
  +
  +|`*osm_default_subdomain*`
  +|This variable overrides the default subdomain to use for exposed
  +link:../../architecture/core_concepts/routes.html[routes].
  +
  +|`*osm_default_node_selector*`
  +|This variable overrides the node selector that projects will use by default
  +when placing pods.
  +|===
  +
  +[[configuring-node-host-labels]]
   
   *Configuring Node Host Labels*
   
  
positive.code: 
  == Running the Ansible Installer
  
  You can now run the Ansible installer:
  
  ----
  # ansible-playbook ~/openshift-ansible/playbooks/byo/config.yml
  
negative.code: ----
  ====
  
  To use this example, modify the file to match your environment and
  specifications, and save it as *_/etc/ansible/hosts_*.
  
  [[multi-master-multi-etcd-multi-node]]
  
  