Enable lo interface in the amphora-haproxy netns

Configure the lo interface in the amphora-haproxy namespace.
It fixes issues with the synchronization of haproxy peer/stick tables
when updating a load balancer configuration.

Story 2009005
Task 42682

Change-Id: I15997acaf12258ec483286dad676efdea8963611
(cherry picked from commit 4443596e29)

octavia/amphorae/backends/agent/api_server/osutils.py

@@ -390,7 +390,7 @@ class RH(BaseOS):
         if not network_dir:
             network_dir = self.get_network_path()
         if not ignore:
-            ignore = shutil.ignore_patterns('ifcfg-eth0*', 'ifcfg-lo*')
+            ignore = shutil.ignore_patterns('ifcfg-eth0*')
         super().create_netns_dir(
             network_dir, netns_network_dir, ignore)
 

octavia/amphorae/backends/agent/api_server/templates/amphora-netns.systemd.j2

@@ -26,7 +26,11 @@ ExecStart=-/bin/sh -c '/usr/bin/sort -k 1 /var/lib/octavia/plugged_interfaces >
 ExecStart=-/bin/sh -c '/sbin/ip link | awk \'{getline n; print $0,n}\' | awk \'{sub(":","",$2)} { for(i=1;i<=NF;i++) if ($i == "link/ether") {print $(i+1) " " $2} }\' | sort -k 1 | join -j 1 - /var/lib/octavia/plugged_interfaces.sorted | awk \'{system("ip link set "$2" netns {{ amphora_nsname }} name "$3"")}\''
 # Bring up all of the namespace interfaces
 {%- if HasIFUPAll %}
+# Ubuntu seems to not correctly set up the lo iface when calling ifup -a
+# Disable it first, before setting it up.
+ExecStart=-/sbin/ip netns exec {{ amphora_nsname }} ifdown lo
 ExecStart=-/sbin/ip netns exec {{ amphora_nsname }} ifup -a
 {%- else %}
+ExecStart=-/sbin/ip netns exec {{ amphora_nsname }} ifup lo
 ExecStart=-/bin/awk '{system("/sbin/ip netns exec {{ amphora_nsname }} ifup " $2)}' /var/lib/octavia/plugged_interfaces
 {%- endif %}

releasenotes/notes/fix-lo-interface-amphora-netns-90fb9934026e1485.yaml

@@ -0,0 +1,8 @@
+---
+fixes:
+  - |
+    Fixed an issue with the ``lo`` interface in the ``amphora-haproxy`` network
+    namespace. The ``lo`` interface was down and prevented haproxy to
+    communicate with other haproxy processes (for persistent stick tables) on
+    configuration change. It delayed old haproxy worker cleanup and increased
+    the memory consumption usage after reloading the configuration.