Allow using a provider network (#701)

* Allow using a provider network

This adds a new option `openstack_provider_network_name` which will take
a name of an existing network and put the servers there. It will also
prevent creating floating IP addresses as the provider network's IPs
should already be accessible without any additional routing required.

Fixes #622

* Requested changes

Don't fail on external/private networks and use role defaults for the
provider network.

* Add missing endif

4 files changed, 34 insertions, 2 deletions

diff --git a/playbooks/provisioning/openstack/README.md b/playbooks/provisioning/openstack/README.md
index b898351e6..4e74627dc 100644
--- a/playbooks/provisioning/openstack/README.md
+++ b/playbooks/provisioning/openstack/README.md
@@ -229,6 +229,24 @@ under the ansible group named `ext_lb`:
     openshift_master_cluster_hostname: "{{ groups.ext_lb.0 }}"
     openshift_master_cluster_public_hostname: "{{ groups.ext_lb.0 }}"
 
+#### Provider Network
+
+Normally, the playbooks create a new Neutron network and subnet and attach
+floating IP addresses to each node. If you have a provider network set up, this
+is all unnecessary as you can just access servers that are placed in the
+provider network directly.
+
+To use a provider network, set its name in `openstack_provider_network_name` in
+`inventory/group_vars/all.yml`.
+
+If you set the provider network name, the `openstack_external_network_name` and
+`openstack_private_network_name` fields will be ignored.
+
+**NOTE**: this will not update the nodes' DNS, so running openshift-ansible
+right after provisioning will fail (unless you're using an external DNS server
+your provider network knows about). You must make sure your nodes are able to
+resolve each other by name.
+
 #### Security notes
 
 Configure required `*_ingress_cidr` variables to restrict public access
diff --git a/playbooks/provisioning/openstack/prerequisites.yml b/playbooks/provisioning/openstack/prerequisites.yml
index a87c06705..f2f720f8b 100644
--- a/playbooks/provisioning/openstack/prerequisites.yml
+++ b/playbooks/provisioning/openstack/prerequisites.yml
@@ -65,10 +65,12 @@
     os_networks_facts:
       name: "{{ openstack_external_network_name }}"
     register: network_result
+    when: not openstack_provider_network_name|default(None)
   - name: Check that network is available
     assert:
       that: "network_result.ansible_facts.openstack_networks"
       msg: "Network {{ openstack_external_network_name }} is not available"
+    when: not openstack_provider_network_name|default(None)
 
   # Check keypair
   # TODO kpilatov: there is no Ansible module for getting OS keypairs
diff --git a/playbooks/provisioning/openstack/sample-inventory/group_vars/all.yml b/playbooks/provisioning/openstack/sample-inventory/group_vars/all.yml
index 5028141d2..0e198342c 100644
--- a/playbooks/provisioning/openstack/sample-inventory/group_vars/all.yml
+++ b/playbooks/provisioning/openstack/sample-inventory/group_vars/all.yml
@@ -16,6 +16,12 @@ openstack_ssh_public_key: "openshift"
 openstack_external_network_name: "public"
 #openstack_private_network_name:  "openshift-ansible-{{ stack_name }}-net"
 
+## If you want to use a provider network, set its name here.
+## NOTE: the `openstack_external_network_name` and
+## `openstack_private_network_name` options will be ignored when using a
+## provider network.
+#openstack_provider_network_name: "provider"
+
 # # Used Images
 # # - set specific images for roles by uncommenting corresponding lines
 # # - note: do not remove openstack_default_image_name definition
diff --git a/playbooks/provisioning/openstack/stack_params.yaml b/playbooks/provisioning/openstack/stack_params.yaml
index 60e9bcf45..484c06889 100644
--- a/playbooks/provisioning/openstack/stack_params.yaml
+++ b/playbooks/provisioning/openstack/stack_params.yaml
@@ -23,8 +23,14 @@ openstack_node_image: "{{ openstack_node_image_name | default(openstack_default_
 openstack_lb_image: "{{ openstack_lb_image_name | default(openstack_default_image_name) }}"
 openstack_etcd_image: "{{ openstack_etcd_image_name | default(openstack_default_image_name) }}"
 openstack_dns_image: "{{ openstack_dns_image_name | default(openstack_default_image_name) }}"
-openstack_private_network: "{{ openstack_private_network_name | default ('openshift-ansible-' + stack_name + '-net') }}"
-external_network: "{{ openstack_external_network_name }}"
+openstack_private_network: >-
+  {% if openstack_provider_network_name | default(None) -%}
+  {{ openstack_provider_network_name }}
+  {%- else -%}
+  {{ openstack_private_network_name | default ('openshift-ansible-' + stack_name + '-net') }}
+  {%- endif -%}
+provider_network: "{{ openstack_provider_network_name | default(None) }}"
+external_network: "{{ openstack_external_network_name | default(None) }}"
 num_etcd: "{{ openstack_num_etcd | default(0) }}"
 num_masters: "{{ openstack_num_masters }}"
 num_nodes: "{{ openstack_num_nodes }}"