agent: add argument to specify python virutal env

When using agentwrapper, the python packages used are the one installed
on the machine.
This commit add an argument to specify the path to a virtual env which
will be used by the agent.

Signed-off-by: Nicolas VINCENT <[email protected]>

labgrid/util/agentwrapper.py

@@ -38,7 +38,7 @@ def __getattr__(self, name):
 
 class AgentWrapper:
 
-    def __init__(self, host=None):
+    def __init__(self, host=None, pyvirtenv=None):
         self.agent = None
         self.loaded = {}
         self.logger = logging.getLogger(f"ResourceExport({host})")
@@ -58,8 +58,12 @@ def __init__(self, host=None):
                 ['rsync', '-e', ' '.join(ssh_opts), '-tq', agent,
                  f'{host}:{agent_remote}'],
             )
+            select_virtenv = []
+            if pyvirtenv is not None:
+                select_virtenv = f'source {pyvirtenv}/bin/activate &&'.split()
+            cmd = select_virtenv + ['python3', agent_remote]
             self.agent = subprocess.Popen(
-                ssh_opts + [host, '--', 'python3', agent_remote],
+                ssh_opts + [host, '--'] + cmd,
                 stdin=subprocess.PIPE,
                 stdout=subprocess.PIPE,
                 start_new_session=True,