satellite: remove socket file on startup

There's an annoying behavior in the python varlink lib. It's described
in the comment. Work around it by proactively removing the socket file
before the server starts.

Signed-off-by: John Mulligan <[email protected]>

Author: phlogistonjohn

sambacc/commands/satellite/keybridge.py

@@ -18,6 +18,7 @@
 
 import argparse
 import logging
+import pathlib
 import signal
 import sys
 import typing
@@ -181,10 +182,22 @@ def _serve(ctx: Context) -> None:
     opts = sambacc.varlink.server.VarlinkServerOptions(ctx.cli.address)
     srv = sambacc.varlink.server.VarlinkServer(opts)
     srv.add_endpoint(sambacc.varlink.keybridge.endpoint(scopes))
+    _clean_socket_file(ctx.cli.address)
     with srv.serve():
         signal.pause()
 
 
+def _clean_socket_file(address: str) -> None:
+    """Remove the old socket file. I think the lib has fixed this in
+    as-yet-unreleased code, but right now every time you start the server when
+    the file exists it fails (but then removes the socket) and so without this
+    cleanup it always needs to be started twice.
+    """
+    assert address.startswith("unix:")
+    path = pathlib.Path(address.split(":", 1)[-1])
+    path.unlink(missing_ok=True)
+
+
 def _new_scope(
     ctx: Context, scope_cfg: sambacc.config.KeyBridgeScopeConfig
 ) -> Scope: