Support batching up commands

[jovial]

When you have around 60 baremetal nodes attached to a single switch, it takes a long time to execute all those commands. This gets worse when you limit the number of concurrent ssh connections.

Here we look to batch up commands to send to the switch together using a single connection. The results of each port's commands are returned when available.

This is implemented using etcd as a queueing system. Commands are added to an input key, then a worker thread processes the available commands for a particular switch device. We pull off the queue using the version at which the keys were added, giving a FIFO style queue. The result of each command set are added to an output key, which the original request thread is watching. Distributed locks are used to serialise the processing of commands for each switch device.

Various neat etcd features are used here to alleviate some of the issues of distributed task coordination, including transactions, leases, watches, historical key/value tracking, etc.

Co-Authored-By: Mark Goddard mark@stackhpc.com

Change-Id: I8c458bbc94df5630cfede5434bcdbe527988059c (cherry picked from commit 45b237b) (cherry picked from commit 465c979)

[jovial]

Changes from upstream version

Removed unsupported argument:

+++ b/networking_generic_switch/batching.py
@@ -321,11 +321,9 @@ class SwitchBatch(object):
             ca_cert = params.get('ca_cert')
             cert_key = params.get('cert_key')
             cert_cert = params.get('cert_cert')
-            api_version = params.get('api_version', 'v3alpha')
             etcd_client = etcd3gw.client(
                 host=host, port=port, protocol=protocol,
                 ca_cert=ca_cert, cert_key=cert_key, cert_cert=cert_cert,
-                api_path='/' + api_version + '/',
                 timeout=30)
             self.queue = SwitchQueue(switch_name, etcd_client)
         else:

get_hostname() not available in wallaby:

--- a/networking_generic_switch/devices/netmiko_devices/__init__.py
+++ b/networking_generic_switch/devices/netmiko_devices/__init__.py
@@ -136,7 +136,7 @@ class NetmikoSwitch(devices.GenericSwitchDevice):
         elif CONF.ngs_coordination.backend_url:
             self.locker = coordination.get_coordinator(
                 CONF.ngs_coordination.backend_url,
-                ('ngs-' + device_utils.get_hostname()).encode('ascii'))
+                ('ngs-' + CONF.host).encode('ascii'))
             self.locker.start()
             atexit.register(self.locker.stop)