srsue: Create netns on demand

Already existing script osmo-gsm-tester_netns_setup.sh is modified to
support only creating the entns without moving an iface to it.

Change-Id: I1b7e186b0146f932fe37fbea68e4dfa3120b7a74

src/osmo_gsm_tester/remote.py

@@ -171,6 +171,13 @@ class RemoteHost(log.Origin):
         SETCAP_NETSYS_ADMIN_BIN = 'osmo-gsm-tester_setcap_netsys_admin.sh'
         self.run_remote_sync('setcap-netsysadm', ('sudo', SETCAP_NETSYS_ADMIN_BIN, binary_path))
 
+    def create_netns(self, netns):
+        '''
+        It creates the netns if it doesn't already exist.
+        '''
+        NETNS_SETUP_BIN = 'osmo-gsm-tester_netns_setup.sh'
+        self.run_remote_sync('create_netns', ('sudo', NETNS_SETUP_BIN, netns))
+
     def change_elf_rpath(self, binary_path, paths):
         '''
         Change RPATH field in ELF executable binary.

src/osmo_gsm_tester/srs_ue.py

@@ -125,6 +125,9 @@ class srsUE(MS):
         self.log('Applying CAP_SYS_ADMIN+CAP_NET_ADMIN capability to srsue')
         self.rem_host.setcap_netsys_admin(remote_binary)
 
+        self.log('Creating netns %s' % self.netns())
+        self.rem_host.create_netns(self.netns())
+
         #'strace', '-ff',
         args = (remote_binary, self.remote_config_file,
                 '--phy.nof_phy_threads=1',
@@ -159,6 +162,9 @@ class srsUE(MS):
         self.log('Applying CAP_SYS_ADMIN+CAP_NET_ADMIN capability to srsue')
         util.setcap_netsys_admin(binary, self.run_dir.new_dir('setcap_netsys_admin'))
 
+        self.log('Creating netns %s' % self.netns())
+        util.create_netns(self.netns(), self.run_dir.new_dir('create_netns'))
+
         args = (binary, os.path.abspath(self.config_file),
                 '--phy.nof_phy_threads=1',
                 '--gw.netns=' + self.netns(),

src/osmo_gsm_tester/util.py

@@ -110,15 +110,22 @@ def setcap_netsys_admin(self, binary, run_dir):
     proc = Process(SETCAP_NETSYS_ADMIN_BIN, run_dir, ['sudo', SETCAP_NETSYS_ADMIN_BIN, binary])
     proc.launch_sync()
 
-def move_iface_to_netns(ifname, netns, run_dir):
+def create_netns(netns, run_dir):
     '''
-    Moves an iface to a netns. It creates the netns if it doesn't exist.
-    fail_iface_not_found=False is handy in order to assume the iface is already
-    in another netns and thus cannot be foud.
+    It creates the netns if it doesn't already exist.
     '''
     from .process import Process
     NETNS_SETUP_BIN = 'osmo-gsm-tester_netns_setup.sh'
-    proc = Process('move_netns', run_dir, ['sudo', NETNS_SETUP_BIN, ifname, netns])
+    proc = Process('create_netns', ('sudo', NETNS_SETUP_BIN, netns))
+    proc.launch_sync()
+
+def move_iface_to_netns(ifname, netns, run_dir):
+    '''
+    Moves an iface to a netns. It creates the netns if it doesn't exist.
+    '''
+    from .process import Process
+    NETNS_SETUP_BIN = 'osmo-gsm-tester_netns_setup.sh'
+    proc = Process('move_netns', run_dir, ['sudo', NETNS_SETUP_BIN, netns, ifname])
     proc.launch_sync()
 
 def import_path_prepend(pathname):

utils/bin/osmo-gsm-tester_netns_setup.sh

@@ -1,11 +1,7 @@
 #!/bin/bash -e
 
-ifname="$1"
-netns="$2"
-shift
-shift
-
-
+netns="$1"
+ifname="$2" # optional
 
 if [ -f "/var/run/netns/${netns}" ]; then
     echo "netns $netns already exists"
@@ -14,6 +10,10 @@ else
     ip netns add "$netns"
 fi
 
+if [ "x$ifname" = "x" ]; then
+    exit 0
+fi
+
 if [ -d "/sys/class/net/${ifname}" ]; then
     echo "Moving iface $ifname to netns $netns"
     ip link set $ifname netns $netns