Gracefully handle lack of network connection.

lib/spack/spack/error.py

@@ -11,3 +11,10 @@ class UnsupportedPlatformError(SpackError):
     """Raised by packages when a platform is not supported"""
     def __init__(self, message):
         super(UnsupportedPlatformError, self).__init__(message)
+
+
+class NoNetworkConnectionError(SpackError):
+    """Raised when an operation needs an internet connection."""
+    def __init__(self, message, url):
+        super(NoNetworkConnectionError, self).__init__(message)
+        self.url = url

lib/spack/spack/package.py

@@ -664,7 +664,9 @@ def fetch_available_versions(self):
             url_regex = os.path.basename(url.wildcard_version(self.url))
             wildcard = self.version.wildcard()
 
+            try:
                 page_map = get_pages(self.list_url, depth=self.list_depth)
+
                 for site, page in page_map.iteritems():
                     strings = re.findall(url_regex, page)
 
@@ -680,6 +682,10 @@ def fetch_available_versions(self):
                              + self.name + " package.",
                              "Use them to tell Spack where to look for versions.")
 
+            except spack.error.NoNetworkConnectionError, e:
+                tty.die("Package.fetch_available_versions couldn't connect to:",
+                        e.url, e.message)
+
         return self._available_versions
 
 

lib/spack/spack/util/web.py

@@ -6,6 +6,7 @@
 from HTMLParser import HTMLParser
 
 import spack
+import spack.error
 import spack.tty as tty
 from spack.util.compression import ALLOWED_ARCHIVE_TYPES
 
@@ -90,12 +91,10 @@ def _spider(args):
                 for d in dicts:
                     pages.update(d)
 
-    except urllib2.HTTPError, e:
+    except urllib2.URLError, e:
         # Only report it if it's the root page.  We ignore errors when spidering.
         if depth == 1:
-            tty.warn("Could not connect to %s" % url, e.reason,
-                     "Package.available_versions requires an internet connection.",
-                     "Version list may be incomplete.")
+            raise spack.error.NoNetworkConnectionError(e.reason, url)
 
     return pages