[ovs-dev] [PATCH v2] ovn-controller: add new external_id 'ovn-cms-options' to Chassis table

[Daniel Alvarez]

This patch makes ovn-controller sets the external_ids key
'ovn-cms-options' to its own Chassis table entry copying its
contents from the same external_ids key in the local OpenvSwitch
database.

The idea behind this patch is to allow setting general options
from the CMS Plugin to a particular chassis.

A good example of an use case is when we want to schedule a router
on a chassis from OpenStack. In this case, we may want to exclude
some nodes because they are more likely to be restarted for
maintenance operations or they simply won't have external connectivity.
This way, if the CMS/deployment tool would set the external_ids
as:

ovs-vsctl set open . external_ids:ovn-cms-options="enable-chassis-as-gw"

Then ovn-controller will write the options to the Chassis table in
southbound database. This value can be later read by the CMS in order
to decide which Chassis are eligible to schedule a router on.

Similarly, this new key would allow to specify additional options to
be consumed by the CMS.

Signed-off-by: Daniel Alvarez <dalvarez at redhat.com>
---
 ovn/controller/chassis.c            | 13 ++++++++++++-
 ovn/controller/ovn-controller.8.xml |  7 +++++++
 ovn/ovn-sb.xml                      |  8 ++++++++
 3 files changed, 27 insertions(+), 1 deletion(-)

diff --git a/ovn/controller/chassis.c b/ovn/controller/chassis.c
index 521b04c..6b5286a 100644
--- a/ovn/controller/chassis.c
+++ b/ovn/controller/chassis.c
@@ -66,6 +66,12 @@ get_bridge_mappings(const struct smap *ext_ids)
     return smap_get_def(ext_ids, "ovn-bridge-mappings", "");
 }
 
+static const char *
+get_cms_options(const struct smap *ext_ids)
+{
+    return smap_get_def(ext_ids, "ovn-cms-options", "");
+}
+
 /* Returns this chassis's Chassis record, if it is available and is currently
  * amenable to a transaction. */
 const struct sbrec_chassis *
@@ -119,6 +125,7 @@ chassis_run(struct controller_ctx *ctx, const char *chassis_id,
     const char *bridge_mappings = get_bridge_mappings(&cfg->external_ids);
     const char *datapath_type =
         br_int && br_int->datapath_type ? br_int->datapath_type : "";
+    const char *cms_options = get_cms_options(&cfg->external_ids);
 
     struct ds iface_types = DS_EMPTY_INITIALIZER;
     ds_put_cstr(&iface_types, "");
@@ -144,16 +151,20 @@ chassis_run(struct controller_ctx *ctx, const char *chassis_id,
             = smap_get_def(&chassis_rec->external_ids, "datapath-type", "");
         const char *chassis_iface_types
             = smap_get_def(&chassis_rec->external_ids, "iface-types", "");
+        const char *chassis_cms_options
+            = get_cms_options(&chassis_rec->external_ids);
 
         /* If any of the external-ids should change, update them. */
         if (strcmp(bridge_mappings, chassis_bridge_mappings) ||
             strcmp(datapath_type, chassis_datapath_type) ||
-            strcmp(iface_types_str, chassis_iface_types)) {
+            strcmp(iface_types_str, chassis_iface_types) ||
+            strcmp(cms_options, chassis_cms_options)) {
             struct smap new_ids;
             smap_clone(&new_ids, &chassis_rec->external_ids);
             smap_replace(&new_ids, "ovn-bridge-mappings", bridge_mappings);
             smap_replace(&new_ids, "datapath-type", datapath_type);
             smap_replace(&new_ids, "iface-types", iface_types_str);
+            smap_replace(&new_ids, "ovn-cms-options", cms_options);
             sbrec_chassis_verify_external_ids(chassis_rec);
             sbrec_chassis_set_external_ids(chassis_rec, &new_ids);
             smap_destroy(&new_ids);
diff --git a/ovn/controller/ovn-controller.8.xml b/ovn/controller/ovn-controller.8.xml
index 2af3db5..0df59ac 100644
--- a/ovn/controller/ovn-controller.8.xml
+++ b/ovn/controller/ovn-controller.8.xml
@@ -150,6 +150,13 @@
         network interface card, enabling encapsulation checksum may incur
         performance loss. In such cases, encapsulation checksums can be disabled.
       </dd>
+
+      <dt><code>external_ids:ovn-cms-options</code></dt>
+      <dd>
+        A list of options that will be consumed by the CMS Plugin and which
+        specific to this particular chassis. An example would be:
+        <code>cms_option1,cms_option2:foo</code>.
+      </dd>
     </dl>
 
     <p>
diff --git a/ovn/ovn-sb.xml b/ovn/ovn-sb.xml
index abc241e..4a75135 100644
--- a/ovn/ovn-sb.xml
+++ b/ovn/ovn-sb.xml
@@ -241,6 +241,14 @@
       read-only. See <code>ovn-controller</code>(8) for more information.
     </column>
 
+    <column name="external_ids" key="ovn-cms-options">
+      <code>ovn-controller</code> populates this key with the set of options
+      configured in the <ref table="Open_vSwitch"
+      column="external_ids:ovn-cms-options"/> column of the Open_vSwitch
+      database's <ref table="Open_vSwitch" db="Open_vSwitch"/> table.
+      See <code>ovn-controller</code>(8) for more information.
+    </column>
+
     <group title="Common Columns">
       The overall purpose of these columns is described under <code>Common
       Columns</code> at the beginning of this document.
-- 
1.8.3.1