Support separate data network for Flannel SDN (#757)

* Support separate data network for Flannel SDN

Document the use case for a separate flannel data network.
Allow Nova servers for openshift cluster to be provisioned
with that isolated data network created and connected to
masters, computes and infra nodes. Do not configure dns
nameservers and router for that network.

Signed-off-by: Bogdan Dobrelya <bdobreli@redhat.com>

* Fix flannel use cases with provider network

Provider network cannot be used with flannel SDN
as the latter requires a separate isolated network,
while the provider network is an externally managed
single network.

Signed-off-by: Bogdan Dobrelya <bdobreli@redhat.com>

* Drop unused data_net_name

Signed-off-by: Bogdan Dobrelya <bdobreli@redhat.com>

5 files changed, 33 insertions, 1 deletions

diff --git a/playbooks/provisioning/openstack/README.md b/playbooks/provisioning/openstack/README.md
index 78d4ffe7c..b9a3b23de 100644
--- a/playbooks/provisioning/openstack/README.md
+++ b/playbooks/provisioning/openstack/README.md
@@ -250,6 +250,9 @@ 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.
 
+**NOTE**: Flannel SDN requires a dedicated containers data network and cannot
+work over a single provider network.
+
 #### Security notes
 
 Configure required `*_ingress_cidr` variables to restrict public access
@@ -267,6 +270,10 @@ be the case for development environments. When turned off, the servers will
 be provisioned omitting the ``yum update`` command. This brings security
 implications though, and is not recommended for production deployments.
 
+Flannel network used for user applications and workloads data should be
+isolated from other networks as it has Neutron ports security disabled.
+Openshift master, compute and infra nodes will be connected to that network.
+
 ##### DNS servers security options
 
 Aside from `node_ingress_cidr` restricting public access to in-stack DNS
@@ -646,7 +653,7 @@ The `increment_by` variable is used to specify by how much the deployment should
 be scaled up (if none exists, it serves as a target number of application nodes).
 The path to `openshift-ansible` directory can be customised by the `openshift_ansible_dir`
 variable. Its value must be an absolute path to `openshift-ansible` and it cannot
-contain the '/' symbol at the end. 
+contain the '/' symbol at the end.
 
 Usage:
 
diff --git a/playbooks/provisioning/openstack/net_vars_check.yaml b/playbooks/provisioning/openstack/net_vars_check.yaml
new file mode 100644
index 000000000..68afde415
--- /dev/null
+++ b/playbooks/provisioning/openstack/net_vars_check.yaml
@@ -0,0 +1,14 @@
+---
+- name: Check the provider network configuration
+  fail:
+    msg: "Flannel SDN requires a dedicated containers data network and can not work over a provider network"
+  when:
+    - openstack_provider_network_name is defined
+    - openstack_private_data_network_name is defined
+
+- name: Check the flannel network configuration
+  fail:
+    msg: "A dedicated containers data network is only supported with Flannel SDN"
+  when:
+    - openstack_private_data_network_name is defined
+    - not openshift_use_flannel|default(False)|bool
diff --git a/playbooks/provisioning/openstack/prerequisites.yml b/playbooks/provisioning/openstack/prerequisites.yml
index f2f720f8b..11a31411e 100644
--- a/playbooks/provisioning/openstack/prerequisites.yml
+++ b/playbooks/provisioning/openstack/prerequisites.yml
@@ -2,6 +2,9 @@
 - hosts: localhost
   tasks:
 
+  # Sanity check of inventory variables
+  - include: net_vars_check.yaml
+
   # Check ansible
   - name: Check Ansible version
     assert:
diff --git a/playbooks/provisioning/openstack/sample-inventory/group_vars/OSEv3.yml b/playbooks/provisioning/openstack/sample-inventory/group_vars/OSEv3.yml
index 2e897102e..70e77662d 100644
--- a/playbooks/provisioning/openstack/sample-inventory/group_vars/OSEv3.yml
+++ b/playbooks/provisioning/openstack/sample-inventory/group_vars/OSEv3.yml
@@ -51,3 +51,7 @@ openshift_override_hostname_check: true
 # NOTE(shadower): Always switch to root on the OSEv3 nodes.
 # openshift-ansible requires an explicit `become`.
 ansible_become: true
+
+# # Flannel networking
+#openshift_use_openshift_sdn: false
+#openshift_use_flannel: true
diff --git a/playbooks/provisioning/openstack/sample-inventory/group_vars/all.yml b/playbooks/provisioning/openstack/sample-inventory/group_vars/all.yml
index fa1fb6c64..83289307d 100644
--- a/playbooks/provisioning/openstack/sample-inventory/group_vars/all.yml
+++ b/playbooks/provisioning/openstack/sample-inventory/group_vars/all.yml
@@ -15,6 +15,10 @@ public_dns_nameservers: []
 openstack_ssh_public_key: "openshift"
 openstack_external_network_name: "public"
 #openstack_private_network_name:  "openshift-ansible-{{ stack_name }}-net"
+# # A dedicated Neutron network name for containers data network
+# # Configures the data network to be separated from openstack_private_network_name
+# # NOTE: this is only supported with Flannel SDN yet
+#openstack_private_data_network_name: "openshift-ansible-{{ stack_name }}-data-net"
 
 ## If you want to use a provider network, set its name here.
 ## NOTE: the `openstack_external_network_name` and