Escape username (#73)

Otherwise bad usernames can cause connection errors

dask_kubernetes/core.py

@@ -2,6 +2,7 @@
 import logging
 import os
 import socket
+import string
 import time
 from urllib.parse import urlparse
 import uuid
@@ -159,7 +160,8 @@ def __init__(
 
         if name is None:
             worker_name = config.get('kubernetes-worker-name', 'dask-{user}-{uuid}')
-            name = worker_name.format(user=getpass.getuser(), uuid=str(uuid.uuid4())[:10], **os.environ)
+            name = worker_name.format(user=escape(getpass.getuser()),
+                                      uuid=str(uuid.uuid4())[:10], **os.environ)
 
         self.pod_template = clean_pod_template(pod_template)
         # Default labels that can't be overwritten
@@ -497,3 +499,10 @@ def select_workers_to_close(scheduler, n_to_close):
             to_close.add(rest.pop())
 
     return [ws.address for ws in to_close]
+
+
+valid_characters = string.ascii_letters + string.digits + '_-.'
+
+
+def escape(s):
+    return ''.join(c for c in s if c in valid_characters)

dask_kubernetes/tests/test_core.py

@@ -444,3 +444,15 @@ def test_repr(cluster):
         assert 'Box' not in text
         assert cluster.scheduler.address in text
         assert "workers=0" in text
+
+
+def test_escape_username(pod_spec, loop, ns):
+    old_logname = os.environ.get('LOGNAME')
+    os.environ['LOGNAME'] = 'foo!'
+
+    try:
+        with KubeCluster(pod_spec, loop=loop, namespace=ns) as cluster:
+            assert 'foo'  in cluster.name
+            assert '!' not in cluster.name
+    finally:
+        os.environ['LOGNAME'] = old_logname