daemon: refactored how to get required commands, added usage of this func for validating distributed servers when added

daemon/core/emulator/coreemu.py

@@ -9,7 +9,7 @@ import core.services
 from core import configservices, utils
 from core.configservice.manager import ConfigServiceManager
 from core.emulator.session import Session
-from core.executables import COMMON_REQUIREMENTS, OVS_REQUIREMENTS, VCMD_REQUIREMENTS
+from core.executables import get_requirements
 from core.services.coreservices import ServiceManager
 
 
@@ -79,13 +79,8 @@ class CoreEmu:
         :return: nothing
         :raises core.errors.CoreError: when an executable does not exist on path
         """
-        requirements = COMMON_REQUIREMENTS
         use_ovs = self.config.get("ovs") == "1"
-        if use_ovs:
+        for requirement in get_requirements(use_ovs):
-            requirements += OVS_REQUIREMENTS
-        else:
-            requirements += VCMD_REQUIREMENTS
-        for requirement in requirements:
             utils.which(requirement, required=True)
 
     def load_services(self) -> None:

daemon/core/emulator/distributed.py

@@ -14,7 +14,8 @@ from fabric import Connection
 from invoke import UnexpectedExit
 
 from core import utils
-from core.errors import CoreCommandError
+from core.errors import CoreCommandError, CoreError
+from core.executables import get_requirements
 from core.nodes.interface import GreTap
 from core.nodes.network import CoreNetwork, CtrlNet
 
@@ -131,8 +132,17 @@ class DistributedController:
         :param name: distributed server name
         :param host: distributed server host address
         :return: nothing
+        :raises CoreError: when there is an error validating server
         """
         server = DistributedServer(name, host)
+        for requirement in get_requirements(self.session.use_ovs()):
+            try:
+                server.remote_cmd(f"which {requirement}")
+            except CoreCommandError:
+                raise CoreError(
+                    f"server({server.name}) failed validation for "
+                    f"command({requirement})"
+                )
         self.servers[name] = server
         cmd = f"mkdir -p {self.session.session_dir}"
         server.remote_cmd(cmd)

daemon/core/executables.py

@@ -14,3 +14,18 @@ OVS_VSCTL: str = "ovs-vsctl"
 COMMON_REQUIREMENTS: List[str] = [SYSCTL, IP, ETHTOOL, TC, EBTABLES, MOUNT, UMOUNT]
 VCMD_REQUIREMENTS: List[str] = [VNODED, VCMD]
 OVS_REQUIREMENTS: List[str] = [OVS_VSCTL]
+
+
+def get_requirements(use_ovs: bool) -> List[str]:
+    """
+    Retrieve executable requirements needed to run CORE.
+
+    :param use_ovs: True if OVS is being used, False otherwise
+    :return: list of executable requirements
+    """
+    requirements = COMMON_REQUIREMENTS
+    if use_ovs:
+        requirements += OVS_REQUIREMENTS
+    else:
+        requirements += VCMD_REQUIREMENTS
+    return requirements