Created attachment 1370869 [details]
logs

Description of problem:
Reinstalling existing host on OVN cluster (with external network provider 'ovirt-provider-ovn' set) doesn't trigger OVN driver deployment. Engine is sending extra variable 'host_deploy_ovn_central=null' when calling ansible-playbook on the host. This results in skipping ovirt-provider-ovn-driver deployment (which requires ovn_central to be set).

Version-Release number of selected component (if applicable):
ovirt-host-deploy-1.7.0-1.el7ev.noarch
ovirt-provider-ovn-1.2.2-1.el7ev.noarch
RHV 4.2.0.2-0.1.el7

How reproducible:
100%

Steps to Reproduce:
1. Add hosts to cluster with external network provider set to empty.
2. Change cluster external network provider to be 'ovirt-provider-ovn'.
3. Reinstall host.

Actual results:
Ansible playbook should run without skipping OVN driver deployment steps, since this is OVN cluster.

Expected results:
Ansible playbook is skipping driver deployment.

Additional info:
Workaround: 
Remove and add the host to the cluster.

engine.log:
2017-12-21 11:54:20,250+02 INFO  [org.ovirt.engine.core.common.utils.ansible.AnsibleExecutor] (EE-ManagedThreadFactory-engine-Thread-2520) [94d5dc3e-a8fc-4888-867e-b0ef18253826] Executing Ansible command:  
[/usr/bin/ansible-playbook, --private-key=/etc/pki/ovirt-engine/keys/engine_id_rsa, --inventory=/tmp/ansible-inventory5396567265985871677, --extra-vars=host_deploy_cluster_version=4.2, --extra-vars=host_dep
loy_gluster_enabled=false, --extra-vars=host_deploy_virt_enabled=true, --extra-vars=host_deploy_vdsm_port=54321, --extra-vars=host_deploy_override_firewall=true, --extra-vars=host_deploy_firewall_type=FIREW
ALLD, --extra-vars=ansible_port=22, --extra-vars=host_deploy_post_tasks=/etc/ovirt-engine/ansible/ovirt-host-deploy-post-tasks.yml, --extra-vars=host_deploy_ovn_tunneling_interface=10.35.128.26, --extra-var
s=host_deploy_ovn_central=null, /usr/share/ovirt-engine/playbooks/ovirt-host-deploy.yml] [Logfile: /var/log/ovirt-engine/host-deploy/ovirt-host-deploy-ansible-20171221115420-vega05.qa.lab.tlv.redhat.com-94d
5dc3e-a8fc-4888-867e-b0ef18253826.log]

ovirt-host-deploy log (note skipped tasks):
2017-12-21 11:54:23,171 p=3287 u=ovirt |  PLAY [all] *********************************************************************
2017-12-21 11:54:23,203 p=3287 u=ovirt |  TASK [Gathering Facts] *********************************************************
2017-12-21 11:54:25,437 p=3287 u=ovirt |  ok: [vega05.qa.lab.tlv.redhat.com]
2017-12-21 11:54:25,459 p=3287 u=ovirt |  TASK [ovirt-host-deploy-facts : Fetch info about VDSM] *************************
2017-12-21 11:54:26,375 p=3287 u=ovirt |  ok: [vega05.qa.lab.tlv.redhat.com]
2017-12-21 11:54:26,398 p=3287 u=ovirt |  TASK [ovirt-host-deploy-facts : Set facts] *************************************
2017-12-21 11:54:26,501 p=3287 u=ovirt |  ok: [vega05.qa.lab.tlv.redhat.com]
2017-12-21 11:54:26,525 p=3287 u=ovirt |  TASK [ovirt-provider-ovn-driver : Install ovirt-provider-ovn-driver] ***********
2017-12-21 11:54:26,579 p=3287 u=ovirt |  skipping: [vega05.qa.lab.tlv.redhat.com]
2017-12-21 11:54:26,602 p=3287 u=ovirt |  TASK [ovirt-provider-ovn-driver : Ensure ovn-controller is started] ************
2017-12-21 11:54:26,651 p=3287 u=ovirt |  skipping: [vega05.qa.lab.tlv.redhat.com]
2017-12-21 11:54:26,673 p=3287 u=ovirt |  TASK [ovirt-provider-ovn-driver : Ensure Open vSwitch is started] **************
2017-12-21 11:54:26,724 p=3287 u=ovirt |  skipping: [vega05.qa.lab.tlv.redhat.com]
2017-12-21 11:54:26,750 p=3287 u=ovirt |  TASK [ovirt-provider-ovn-driver : Configure OVN for oVirt] *********************
2017-12-21 11:54:26,801 p=3287 u=ovirt |  skipping: [vega05.qa.lab.tlv.redhat.com]
2017-12-21 11:54:26,830 p=3287 u=ovirt |  TASK [ovirt-host-deploy-libvirt-guests : Setup the configuration file] *********
2017-12-21 11:54:28,527 p=3287 u=ovirt |  ok: [vega05.qa.lab.tlv.redhat.com]
2017-12-21 11:54:28,551 p=3287 u=ovirt |  TASK [ovirt-host-deploy-libvirt-guests : Start libvirt-guests service and ensure its enabled] ***
2017-12-21 11:54:29,631 p=3287 u=ovirt |  changed: [vega05.qa.lab.tlv.redhat.com]
2017-12-21 11:54:29,654 p=3287 u=ovirt |  TASK [ovirt-host-deploy-firewalld : Check if VDSM version is supported for FirewallD] ***
2017-12-21 11:54:29,717 p=3287 u=ovirt |  skipping: [vega05.qa.lab.tlv.redhat.com]
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