Create /run/netns if does not exist

Unlike docker with podman you can't mount a host directory
that does not exist. We did some work as part of bug 1799638
take care of this for reboots. However, we need it to be created
for fresh installations, as nodes are not necessarily rebooted
after installing paunch. The real issue without reboots did not
surface before the next patch in this series, as we were using
cni0 bridge network for some containers and that resulted in
namespace being created and the directory existing for
neutron_dhcp and neutron_l3 containers in step 4 to mount them.

This patch creates/removes a temp namespace in host_prep_tasks
to ensure that the directory exists.

Change-Id: I19d660168c98887a5e352b3413235888c800760d
Related-Bug: #1799638

docker/services/neutron-dhcp.yaml

@@ -259,6 +259,14 @@ outputs:
       host_prep_tasks:
         list_concat:
           - {get_attr: [NeutronLogging, host_prep_tasks]}
+          - - name: create /run/netns with temp namespace
+              command: ip netns add ns_temp
+              register: ipnetns_add_result
+              ignore_errors: True
+          - - name: remove temp namespace
+              command: ip netns delete ns_temp
+              ignore_errors: True
+              when: ipnetns_add_result.rc == 0
           - - name: create /var/lib/neutron
               file:
                 path: /var/lib/neutron

docker/services/neutron-l3.yaml

@@ -256,6 +256,14 @@ outputs:
       host_prep_tasks:
         list_concat:
           - {get_attr: [NeutronLogging, host_prep_tasks]}
+          - - name: create /run/netns with temp namespace
+              command: ip netns add ns_temp
+              register: ipnetns_add_result
+              ignore_errors: True
+          - - name: remove temp namespace
+              command: ip netns delete ns_temp
+              ignore_errors: True
+              when: ipnetns_add_result.rc == 0
           - - name: create /var/lib/neutron
               file:
                 path: /var/lib/neutron

docker/services/ovn-metadata.yaml

@@ -210,6 +210,14 @@ outputs:
       host_prep_tasks:
         list_concat:
           - {get_attr: [NeutronLogging, host_prep_tasks]}
+          - - name: create /run/netns with temp namespace
+              command: ip netns add ns_temp
+              register: ipnetns_add_result
+              ignore_errors: True
+          - - name: remove temp namespace
+              command: ip netns delete ns_temp
+              ignore_errors: True
+              when: ipnetns_add_result.rc == 0
           - - name: create /var/lib/neutron
               file:
                 path: /var/lib/neutron