Replaces user input from IP address to more convenient interface name (…

…#20)

README.md

@@ -9,7 +9,7 @@ If you wish to change the default configuration, create a YAML configuration fil
 ```yaml
 ---
 srs-enb-ue:
-  bind-address: <Local IP address to bind for GTP and S1AP connection.>
+  bind-interface: <Local interface to bind for GTP and S1AP connection.>
   enb-name: <eNodeB name.>
   enb-mcc: <EnodeB Mobile Country Code (MCC).>
   enb-mnc: <EnodeB Mobile Network Code (MNC).>

config.yaml

@@ -2,11 +2,10 @@
 # See LICENSE file for licensing details.
 
 options:
-  bind-address:
+  bind-interface:
     type: string
     description: |
-      Local IP address to bind for GTP and S1AP connection.
-    default: ""
+      Local interface to bind for GTP and S1AP connection.
   enb-name:
     type: string
     description: |

src/charm.py

@@ -238,11 +238,11 @@ def _mme_address(self) -> Optional[str]:
     @property
     def _bind_address(self) -> Optional[str]:
         """Returns bind address."""
-        return (
-            bind_address
-            if (bind_address := self.model.config.get("bind-address"))
-            else ip_from_default_iface()
-        )
+        bind_interface = self.model.config.get("bind-interface")
+        if not bind_interface:
+            return ip_from_default_iface()
+        else:
+            return get_iface_ip_address(iface=bind_interface)
 
 
 if __name__ == "__main__":

src/utils.py

@@ -24,10 +24,10 @@ def ip_from_default_iface() -> Optional[str]:
     """Returns the default interface's IP address."""
     default_gateway = netifaces.gateways()["default"]
     if netifaces.AF_INET in default_gateway:
-        _, iface = netifaces.gateways()["default"][netifaces.AF_INET]
+        _, iface = default_gateway[netifaces.AF_INET]
         default_interface = netifaces.ifaddresses(iface)
         if netifaces.AF_INET in default_interface:
-            return netifaces.ifaddresses(iface)[netifaces.AF_INET][0].get("addr")
+            return default_interface[netifaces.AF_INET][0].get("addr")
     return None
 
 

tests/unit/test_charm.py

@@ -76,6 +76,27 @@ def test_given_lte_core_relation_when_mme_address_is_available_then_srsenb_servi
             description="SRS eNodeB Emulator Service",
         )
 
+    @patch("linux_service.Service.restart", new=Mock)
+    @patch("linux_service.Service.enable", new=Mock)
+    @patch("linux_service.Service.create")
+    @patch("charm.get_iface_ip_address")
+    def test_given_user_specified_bind_interface_when_lte_core_available_then_interface_is_used(
+        self, patch_get_iface_ip_address, patch_service_create
+    ):
+        self.harness.update_config(key_values={"bind-interface": "eth1"})
+        eth_1_ip_address = "5.6.7.8"
+        patch_get_iface_ip_address.return_value = eth_1_ip_address
+
+        self.harness.set_leader(True)
+
+        self.create_lte_core_relation()
+
+        patch_service_create.assert_called_with(
+            command=f"/snap/bin/srsran.srsenb --enb.mme_addr=1.2.3.4 --enb.gtp_bind_addr={eth_1_ip_address} --enb.s1c_bind_addr={eth_1_ip_address} --enb.name=dummyENB01 --enb.mcc=001 --enb.mnc=01 --enb_files.rr_config=/snap/srsran/current/config/rr.conf --enb_files.sib_config=/snap/srsran/current/config/sib.conf /snap/srsran/current/config/enb.conf --rf.device_name=zmq --rf.device_args=fail_on_disconnect=true,tx_port=tcp://*:2000,rx_port=tcp://localhost:2001,id=enb,base_srate=23.04e6",  # noqa: E501
+            user="root",
+            description="SRS eNodeB Emulator Service",
+        )
+
     @patch("charm.ip_from_default_iface", new=Mock)
     @patch("linux_service.Service.restart")
     @patch("linux_service.Service.enable", new=Mock)
@@ -158,7 +179,6 @@ def test_given_any_config_and_started_is_false_when_on_config_changed_then_srsen
         patch_service_restart.assert_not_called()
 
     @patch("charm.ip_from_default_iface", new=Mock)
-    @patch("charm.get_iface_ip_address", new=Mock)
     @patch("linux_service.Service.restart", new=Mock)
     @patch("linux_service.Service.enable", new=Mock)
     @patch("linux_service.Service.create")

tests/unit/test_utils.py

@@ -4,7 +4,9 @@
 import unittest
 from unittest.mock import patch
 
-from utils import shell
+import netifaces  # type: ignore[import]
+
+from utils import get_iface_ip_address, ip_from_default_iface, shell
 
 
 class TestUtils(unittest.TestCase):
@@ -15,3 +17,61 @@ def test_given_command_when_shell_then_subprocess_run(self, patch_run):
         shell(command=command)
 
         patch_run.assert_called_with(command, shell=True, stdout=-1, encoding="utf-8")
+
+    @patch("netifaces.ifaddresses")
+    @patch("netifaces.gateways")
+    def test_given_default_interface_has_ip_when_ip_from_default_iface_then_ip_is_returned(
+        self, patch_gateways, patch_addresses
+    ):
+        default_gateway = "192.168.2.1"
+        ip_address = "192.168.2.122"
+        interface_name = "eth0"
+        patch_gateways.return_value = {
+            "default": {netifaces.AF_INET: (default_gateway, interface_name)}
+        }
+        patch_addresses.return_value = {netifaces.AF_INET: [{"addr": ip_address}]}
+
+        assert ip_from_default_iface() == ip_address
+
+    @patch("netifaces.ifaddresses")
+    @patch("netifaces.gateways")
+    def test_given_no_default_gateway_ip_when_ip_from_default_iface_then_none_is_returned(  # noqa: E501
+        self, patch_gateways, patch_addresses
+    ):
+        patch_gateways.return_value = {"default": {}}
+        patch_addresses.return_value = {}
+
+        assert not ip_from_default_iface()
+
+    @patch("netifaces.ifaddresses")
+    @patch("netifaces.gateways")
+    def test_given_default_interface_does_not_have_an_ip_when_ip_from_default_iface_then_none_is_returned(  # noqa: E501
+        self, patch_gateways, patch_addresses
+    ):
+        default_gateway = "192.168.2.1"
+        interface_name = "eth0"
+        patch_gateways.return_value = {
+            "default": {netifaces.AF_INET: (default_gateway, interface_name)}
+        }
+        patch_addresses.return_value = {}
+
+        assert not ip_from_default_iface()
+
+    @patch("netifaces.ifaddresses")
+    def test_given_interface_has_ip_address_when_get_iface_ip_address_then_ip_is_returned(
+        self, patch_addresses
+    ):
+        interface = "eth0"
+        ip_address = "1.2.3.4"
+        patch_addresses.return_value = {netifaces.AF_INET: [{"addr": ip_address}]}
+
+        assert get_iface_ip_address(interface) == ip_address
+
+    @patch("netifaces.ifaddresses")
+    def test_given_interface_does_not_exist_when_get_iface_ip_address_then_none_is_returned(
+        self, patch_addresses
+    ):
+        interface = "eth0"
+        patch_addresses.side_effect = ValueError()
+
+        assert not get_iface_ip_address(interface)