Sombrero's webfinger support doesn't break if the remote host is unreachable

or times out. Tests updated.

Sombrero webfinger tests gain a context manager suppress_thread_exceptions(), to stop spurious exceptions being
reported if they occur in threads other than the main thread. See https://stackoverflow.com/questions/63206653/ .

kepi/sombrero_sendpub/tests/__init__.py

@@ -0,0 +1,15 @@
+import threading
+from contextlib import contextmanager
+
+@contextmanager
+def suppress_thread_exceptions():
+    """
+    Context manager which causes exceptions in threads not to
+    be printed. See https://stackoverflow.com/questions/63206653/ .
+    """
+    orig = threading.excepthook
+    threading.excepthook = lambda a: None
+    try:
+        yield
+    finally:
+        threading.excepthook = orig

kepi/sombrero_sendpub/tests/test_webfinger.py

@@ -7,6 +7,7 @@
 from unittest import skip
 from django.test import TestCase
 from kepi.sombrero_sendpub.webfinger import get_webfinger
+from . import suppress_thread_exceptions
 import httpretty
 import logging
 import requests
@@ -166,10 +167,11 @@ class TestWebfinger(TestCase):
                 body = timeout,
                 )
 
-        webfinger = get_webfinger(
-                EXAMPLE_USERNAME,
-                EXAMPLE_HOSTNAME,
-                )
+        with suppress_thread_exceptions():
+            webfinger = get_webfinger(
+                    EXAMPLE_USERNAME,
+                    EXAMPLE_HOSTNAME,
+                    )
 
         self.assertEqual(
                 webfinger.url,
@@ -192,10 +194,11 @@ class TestWebfinger(TestCase):
                 body = no_such_host,
                 )
 
-        webfinger = get_webfinger(
-                EXAMPLE_USERNAME,
-                EXAMPLE_HOSTNAME,
-                )
+        with suppress_thread_exceptions():
+            webfinger = get_webfinger(
+                    EXAMPLE_USERNAME,
+                    EXAMPLE_HOSTNAME,
+                    )
 
         self.assertEqual(
                 webfinger.url,

kepi/sombrero_sendpub/webfinger.py

@@ -20,18 +20,27 @@ def get_webfinger(username, hostname):
     url = f'https://{hostname}/.well-known/'+\
             f'webfinger?acct={username}'
 
-    response = requests.get(
-            url,
-            headers = {
-                'Accept': 'application/activity+json',
-                },
-            )
+    try:
+        response = requests.get(
+                url,
+                headers = {
+                    'Accept': 'application/activity+json',
+                    },
+                )
+    except requests.ConnectionError:
+        logger.info("webfinger: Connection to %s failed",
+                hostname)
+        result.status = 0
+        result.save()
+        return result
 
     result.status = response.status_code
 
     if response.status_code!=200:
         result.save()
-        logger.info("Unexpected status code from webfinger lookup")
+        logger.info("webfinger: Unexpected status code %d from lookup of %s@%s",
+                response.status_code,
+                username, hostname)
         return result
 
     self_link = [x for x in response.json()['links']
@@ -39,7 +48,8 @@ def get_webfinger(username, hostname):
 
     if not self_link:
         result.save()
-        logger.info("Webfinger has no activity information")
+        logger.info("webfinger: retrieved %s@%s, which has no activity information",
+                username, hostname)
         return result
 
     result.url = self_link[0]['href']