Add multi-node devstack support to VPNaaS

Modify devstack plugin to support multi-node confgurations
(i.e. where the network node is split from the controller node).

DocImpact: Migrate HowTo wiki page to additional devref text

Change-Id: Iac5756ffe75b2125faace54b74b296036905a9b0
Signed-off-by: Ryan Moats <rmoats@us.ibm.com>

devstack/README.md

@@ -1,26 +1,3 @@
-This directory contains the neutron-vpnaas devstack plugin.  To
+This directory contains the neutron-vpnaas devstack plugin.  Please
-configure VPNaaS, in the [[local|localrc]] section, you will need
+see the devref for how to set up VPNaaS with devstack.
-to enable the neutron-vpnaas devstack plugin.
 
-Add a line of the form:
-
-    enable_plugin neutron-vpnaas <GITURL> [GITREF]
-
-where
-
-    <GITURL> is the URL of a neutron-vpnaas repository
-    [GITREF] is an optional git ref (branch/ref/tag).  The default is
-             master.
-
-For example
-
-    enable_plugin neutron-vpnaas https://git.openstack.org/openstack/neutron-vpnaas stable/kilo
-
-Note: Since the VPN agent process, is a subclass of the L3 agent,
-which is a subclass of the FW agent, the DevStack plugin will
-check for the FW service being enabled, and if so, will include
-the config file specified in Q_FWAAS_CONF_FILE (default is
-fwaas_driver.ini).
-
-For more information, see the "Externally Hosted Plugins" section of
-http://docs.openstack.org/developer/devstack/plugins.html.

devstack/plugin.sh

@@ -5,7 +5,9 @@ set -o xtrace
 
 function neutron_vpnaas_install {
     setup_develop $NEUTRON_VPNAAS_DIR
-    neutron_agent_vpnaas_install_agent_packages
+    if is_service_enabled q-l3; then
+        neutron_agent_vpnaas_install_agent_packages
+    fi
 }
 
 function neutron_agent_vpnaas_install_agent_packages {
@@ -26,7 +28,10 @@ function neutron_vpnaas_configure_common {
     inicomment $NEUTRON_VPNAAS_CONF service_providers service_provider
     iniadd $NEUTRON_VPNAAS_CONF service_providers service_provider $NEUTRON_VPNAAS_SERVICE_PROVIDER
     iniset $NEUTRON_CONF DEFAULT service_plugins $Q_SERVICE_PLUGIN_CLASSES
-    $NEUTRON_BIN_DIR/neutron-db-manage --service vpnaas --config-file $NEUTRON_CONF --config-file /$Q_PLUGIN_CONF_FILE upgrade head
+}
+
+function neutron_vpnaas_configure_db {
+    $NEUTRON_BIN_DIR/neutron-db-manage --subproject neutron-vpnaas --config-file $NEUTRON_CONF --config-file /$Q_PLUGIN_CONF_FILE upgrade head
 }
 
 function neutron_vpnaas_configure_agent {
@@ -83,17 +88,27 @@ if [[ "$1" == "stack" && "$2" == "install" ]]; then
     neutron_vpnaas_install
 
 elif [[ "$1" == "stack" && "$2" == "post-config" ]]; then
-    echo_summary "Configuring neutron-vpnaas"
     neutron_vpnaas_generate_config_files
     neutron_vpnaas_configure_common
-    neutron_vpnaas_configure_agent
+    if is_service_enabled q-svc; then
+        echo_summary "Configuring neutron-vpnaas on controller"
+        neutron_vpnaas_configure_db
+    fi
+    if is_service_enabled q-l3; then
+        echo_summary "Configuring neutron-vpnaas agent"
+        neutron_vpnaas_configure_agent
+    fi
 
 elif [[ "$1" == "stack" && "$2" == "extra" ]]; then
-    echo_summary "Initializing neutron-vpnaas"
+    if is_service_enabled q-l3; then
-    neutron_vpnaas_start
+        echo_summary "Initializing neutron-vpnaas"
+        neutron_vpnaas_start
+    fi
 
 elif [[ "$1" == "unstack" ]]; then
-    neutron_vpnaas_stop
+    if is_service_enabled q-l3; then
+        neutron_vpnaas_stop
+    fi
 
 # NOP for clean step
 

doc/source/devref/devstack.rst

@@ -0,0 +1,46 @@
+===============================
+Configuring VPNaaS for DevStack
+===============================
+
+-----------------------
+Multinode vs All-In-One
+-----------------------
+
+Devstack typically runs in single or "All-In-One" (AIO) mode.  However, it
+can also be deployed to run on multiple nodes. For VPNaaS, running on an
+AIO setup is simple, as everything happens on the same node. However, to
+deploy to a multinode setup requires the following things to happen:
+
+#. Each controller node requires database migrations in support of running
+   VPNaaS.
+#. Each network node that would run the L3 agent needs to run the Neutron
+   VPNaaS agent in its place.
+
+Therefore, the devstack plugin script needs some extra logic.
+
+----------------
+How to Configure
+----------------
+
+To configure VPNaaS, it is only necessary to enable the neutron-vpnaas
+devstack plugin by adding the following line to the [[local|localrc]]
+section of devstack's local.conf file::
+
+   enable_plugin neutron-vpnaas <GITURL> [BRANCH]
+
+   <GITURL> is the URL of a neutron-vpnaas repository
+   [BRANCH] is an optional git ref (branch/ref/tag).  The default is master.
+
+   For example::
+
+       enable_plugin neutron-vpnaas https://git.openstack.org/openstack/neutron-vpnaas stable/kilo
+
+This VPNaaS devstack plugin code will then
+
+#. Install the common VPNaaS configuration and code,
+
+#. Apply database migrations on nodes that are running the controller (as
+   determined by enabling the q-svc service),
+
+#. Run the VPNaaS agent on nodes that would normally be running the L3 agent
+   (as determined by enabling the q-l3 service).

doc/source/devref/index.rst

@@ -42,12 +42,13 @@ VPNaaS Internals
 
    multiple-local-subnets
 
-
 Testing
 -------
 .. toctree::
    :maxdepth: 3
 
+   devstack
+
 .. todo::
 
    Add notes about functional testing, with info on how