issue #754: support MITOGEN_UNIX_DIR environment variable

ansible_mitogen/process.py

@@ -627,7 +627,10 @@ class MuxProcess(object):
         #: MuxProcess CPU index.
         self.index = index
         #: Individual path of this process.
-        self.path = mitogen.unix.make_socket_path()
+        self.path = mitogen.unix.make_socket_path(
+            # issue #754: overlong temp paths may easily overflow sockaddr_un
+            dir=os.environ.get('MITOGEN_UNIX_DIR'),
+        )
 
     def start(self):
         self.pid = os.fork()

docs/ansible_detailed.rst

@@ -515,6 +515,18 @@ In summary, for each task Ansible may create one or more of:
 * ``$TMPDIR/ansible_<modname>_payload_.../`` owned by the become user,
 * ``$TMPDIR/ansible-module-tmp-.../`` owned by the become user.
 
+Temporary Files (Controller)
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+To create UNIX sockets used for inter-process communication on the Ansible
+controller host, Mitogen normally uses a temporary directory selected
+by the :mod:`tempfile` module, however is possible the selected directory
+cannot be used as its name its path exceeds the system-defined 108 byte limit
+on UNIX socket paths.
+
+In this case, the ``MITOGEN_UNIX_DIR`` environment variable may be used to
+define an alternative directory.
+
 
 Mitogen for Ansible
 ^^^^^^^^^^^^^^^^^^^

mitogen/unix.py

@@ -79,8 +79,12 @@ def is_path_dead(path):
     return False
 
 
-def make_socket_path():
+def make_socket_path(dir=None):
-    return tempfile.mktemp(prefix='mitogen_unix_', suffix='.sock')
+    return tempfile.mktemp(
+        prefix='mitogen_unix_',
+        suffix='.sock',
+        dir=dir,
+    )
 
 
 class ListenerStream(mitogen.core.Stream):