Merge pull request #208 from cnweaver/missing-crossbar

Deal gracefully with crossbar not being found

README.rst

@@ -50,6 +50,9 @@ There are also several Python package dependencies, which are listed in the
 
 .. _requirements.txt: requirements.txt
 
+Additionally ``crossbar`` is a required dependency which is not automatically
+installed. It can be installed with pip or run via Docker.
+
 Installation
 ------------
 Clone this repository and install using pip::

docs/user/dependencies.rst

@@ -20,18 +20,21 @@ Python Dependencies
 All python dependencies for OCS are listed in (and automatically installed via)
 the ``requirements.txt`` file. Some of the dependencies are:
 
-* `crossbar.io`_ - An implementation of a WAMP router.
 * `Autobahn`_ - Provides open-source implementations of WAMP.
 * `twisted`_ - Used with Autobahn for networking.
 
 Other Dependencies
 ``````````````````
 
+* `crossbar.io`_ - An implementation of a WAMP router.
 * Docker_ - Containerization software used for deploying several SO written
   packages.
 * `Docker Compose`_ - CLI tool for running multi-container Docker
   applications.
 
+Crossbar may be installed via pip if it will be used without Docker; if it
+will be used with Docker it does not need to be separately installed.
+
 Operating System
 ````````````````
 Deploying in Docker makes OCS almost OS independent. If running components

ocs/site_config.py

@@ -8,6 +8,7 @@
 import argparse
 import collections
 import deprecation
+import errno
 
 
 class SiteConfig:
@@ -134,6 +135,10 @@ def from_dict(cls, data, parent=None):
         self = cls()
         self.parent = parent
         self.binary = data.get('bin', shutil.which('crossbar'))
+        if self.binary is None:
+            raise RuntimeError("Unable to locate crossbar binary")
+        if not os.path.exists(self.binary):
+            raise FileNotFoundError(errno.ENOENT, os.strerror(errno.ENOENT), self.binary)
         self.cbdir = data.get('config-dir')
         if self.cbdir is None:
             self.cbdir_args = []

tests/test_site_config.py

@@ -1,7 +1,7 @@
-from unittest.mock import MagicMock
+from unittest.mock import MagicMock, patch
 
 import pytest
-from ocs.site_config import get_control_client
+from ocs.site_config import get_control_client, CrossbarConfig
 
 
 class TestGetControlClient:
@@ -44,3 +44,17 @@ def test_none_client_type_wo_wamp_http_site(self):
 
         with pytest.raises(ValueError):
             get_control_client('test', site=mock_site, client_type=None)
+
+    def test_missing_crossbar(self):
+        crossbar_found = MagicMock(return_value="someplace/bin/crossbar")
+        with patch("shutil.which", crossbar_found), \
+                patch("os.path.exists", MagicMock(return_value=True)):
+            config = CrossbarConfig.from_dict({})
+            assert config.binary == "someplace/bin/crossbar"
+
+        crossbar_not_found = MagicMock(return_value=None)
+        with patch("shutil.which", crossbar_not_found), pytest.raises(RuntimeError):
+            config = CrossbarConfig.from_dict({})
+
+        with pytest.raises(FileNotFoundError):
+            config = CrossbarConfig.from_dict({"bin": "not/a/valid/path/to/crossbar"})