[OVN] Update sample local.conf to mention OVN_BUILD_FROM_SOURCE

Using OVN from packages was introduced in devstack via
https://review.opendev.org/c/openstack/devstack/+/763402

This change updates the sample files to make users aware of it,
especially when specifying the OVN branch to be used.

Change-Id: Ibfbdd712e49d1fb8522bcc39357be0f311ce3f5c

devstack/ovn-compute-local.conf.sample

@@ -26,12 +26,6 @@ Q_ML2_TENANT_NETWORK_TYPE="geneve"
 # Enable devstack spawn logging
 LOGFILE=$DEST/logs/stack.sh.log
 
-# The DevStack plugin defaults to using the ovn branch from the official ovs
-# repo.  You can optionally use a different one.  For example, you may want to
-# use the latest patches in blp's ovn branch:
-#OVN_REPO=https://github.com/blp/ovs-reviews.git
-#OVN_BRANCH=ovn
-
 enable_plugin neutron https://opendev.org/openstack/neutron
 
 disable_all_services
@@ -54,6 +48,17 @@ OVN_SB_REMOTE=tcp:$SERVICE_HOST:6642
 # DevStack runs.
 #OVN_UUID=
 
+# The DevStack plugin defaults to using the ovn branch from the official ovs
+# repo.  You can optionally use a different one.  For example, you may want to
+# use the latest patches in blp's ovn branch (and see OVN_BUILD_FROM_SOURCE):
+#OVN_REPO=https://github.com/blp/ovs-reviews.git
+#OVN_BRANCH=ovn
+
+# NOTE: When specifying the branch, as shown above, you must also enable this!
+# By default, OVN will be installed from packages. In order to build OVN from
+# source, set OVN_BUILD_FROM_SOURCE=True
+#OVN_BUILD_FROM_SOURCE=False
+
 # Whether or not to build custom openvswitch kernel modules from the ovs git
 # tree. This is disabled by default.  This is required unless your distro kernel
 # includes ovs+conntrack support.  This support was first released in Linux 4.3,

devstack/ovn-db-local.conf.sample

@@ -16,12 +16,6 @@ SERVICE_PASSWORD=password
 SERVICE_TOKEN=password
 ADMIN_PASSWORD=password
 
-# The DevStack plugin defaults to using the ovn branch from the official ovs
-# repo.  You can optionally use a different one.  For example, you may want to
-# use the latest patches in blp's ovn branch:
-#OVN_REPO=https://github.com/blp/ovs-reviews.git
-#OVN_BRANCH=ovn
-
 Q_AGENT=ovn
 NEUTRON_AGENT=$Q_AGENT
 
@@ -40,6 +34,17 @@ enable_service ovn-northd
 # DevStack runs.
 #OVN_UUID=
 
+# The DevStack plugin defaults to using the ovn branch from the official ovs
+# repo.  You can optionally use a different one.  For example, you may want to
+# use the latest patches in blp's ovn branch (and see OVN_BUILD_FROM_SOURCE):
+#OVN_REPO=https://github.com/blp/ovs-reviews.git
+#OVN_BRANCH=ovn
+
+# NOTE: When specifying the branch, as shown above, you must also enable this!
+# By default, OVN will be installed from packages. In order to build OVN from
+# source, set OVN_BUILD_FROM_SOURCE=True
+#OVN_BUILD_FROM_SOURCE=False
+
 # Whether or not to build custom openvswitch kernel modules from the ovs git
 # tree. This is enabled by default.  This is required unless your distro kernel
 # includes ovs+conntrack support.  This support was first released in Linux 4.3,

devstack/ovn-local.conf.sample

@@ -24,12 +24,6 @@ Q_ML2_TENANT_NETWORK_TYPE="geneve"
 # Enable devstack spawn logging
 LOGFILE=$DEST/logs/stack.sh.log
 
-# The DevStack plugin defaults to using the ovn branch from the official ovs
-# repo.  You can optionally use a different one.  For example, you may want to
-# use the latest patches in blp's ovn branch:
-#OVN_REPO=https://github.com/blp/ovs-reviews.git
-#OVN_BRANCH=ovn
-
 enable_service ovn-northd
 enable_service ovn-controller
 enable_service q-ovn-metadata-agent
@@ -83,6 +77,17 @@ disable_service cinder c-sch c-api c-vol
 # Default value is leastloaded.
 #OVN_L3_SCHEDULER=leastloaded
 
+# The DevStack plugin defaults to using the ovn branch from the official ovs
+# repo.  You can optionally use a different one.  For example, you may want to
+# use the latest patches in blp's ovn branch (and see OVN_BUILD_FROM_SOURCE):
+#OVN_REPO=https://github.com/blp/ovs-reviews.git
+#OVN_BRANCH=ovn
+
+# NOTE: When specifying the branch, as shown above, you must also enable this!
+# By default, OVN will be installed from packages. In order to build OVN from
+# source, set OVN_BUILD_FROM_SOURCE=True
+#OVN_BUILD_FROM_SOURCE=False
+
 # Whether or not to build custom openvswitch kernel modules from the ovs git
 # tree. This is disabled by default.  This is required unless your distro kernel
 # includes ovs+conntrack support.  This support was first released in Linux 4.3,

devstack/ovn-vtep-local.conf.sample

@@ -16,12 +16,6 @@ SERVICE_PASSWORD=password
 SERVICE_TOKEN=password
 ADMIN_PASSWORD=password
 
-# The DevStack plugin defaults to using the ovn branch from the official ovs
-# repo.  You can optionally use a different one.  For example, you may want to
-# use the latest patches in blp's ovn branch:
-#OVN_REPO=https://github.com/blp/ovs-reviews.git
-#OVN_BRANCH=ovn
-
 enable_plugin neutron https://git.openstack.org/openstack/neutron
 
 disable_all_services
@@ -32,6 +26,17 @@ enable_service ovn-controller-vtep
 # DevStack runs.
 #OVN_UUID=
 
+# The DevStack plugin defaults to using the ovn branch from the official ovs
+# repo.  You can optionally use a different one.  For example, you may want to
+# use the latest patches in blp's ovn branch (and see OVN_BUILD_FROM_SOURCE):
+#OVN_REPO=https://github.com/blp/ovs-reviews.git
+#OVN_BRANCH=ovn
+
+# NOTE: When specifying the branch, as shown above, you must also enable this!
+# By default, OVN will be installed from packages. In order to build OVN from
+# source, set OVN_BUILD_FROM_SOURCE=True
+#OVN_BUILD_FROM_SOURCE=False
+
 # Whether or not to build custom openvswitch kernel modules from the ovs git
 # tree. This is disabled by default.  This is required unless your distro kernel
 # includes ovs+conntrack support.  This support was first released in Linux 4.3,