Allow nodes to be configured and launched by phase.

We're going to need this for obfs4, for which we cannot initialize
the client until the bridge has been running long enough to generate
its keys.

lib/chutney/TorNet.py

@@ -922,6 +922,15 @@ DEFAULTS = {
     'dns_conf': (os.environ.get('CHUTNEY_DNS_CONF', '/etc/resolv.conf')
                         if 'CHUTNEY_DNS_CONF' in os.environ
                         else None),
+
+    # The phase at which this instance needs to be
+    # configured/launched, if we're doing multiphase
+    # configuration/launch.
+    'config_phase' : 1,
+    'launch_phase' : 1,
+
+    'CUR_CONFIG_PHASE': getenv_int('CHUTNEY_CONFIG_PHASE', 1),
+    'CUR_LAUNCH_PHASE': getenv_int('CHUTNEY_LAUNCH_PHASE', 1),
 }
 
 
@@ -1148,17 +1157,21 @@ class Network(object):
             n.getBuilder().checkConfig(self)
 
     def configure(self):
-        self.create_new_nodes_dir()
+        phase = self._dfltEnv['CUR_CONFIG_PHASE']
+        if phase == 1:
+            self.create_new_nodes_dir()
         network = self
         altauthlines = []
         bridgelines = []
-        builders = [n.getBuilder() for n in self._nodes]
+        all_builders = [ n.getBuilder() for n in self._nodes ]
+        builders = [ b for b in all_builders
+                     if b._env['config_phase'] == phase ]
         self._checkConfig()
 
         # XXX don't change node names or types or count if anything is
         # XXX running!
 
-        for b in builders:
+        for b in all_builders:
             b.preConfig(network)
             altauthlines.append(b._getAltAuthLines(
                 self._dfltEnv['hasbridgeauth']))
@@ -1188,7 +1201,9 @@ class Network(object):
         # format polling correctly - avoid printing a newline
         sys.stdout.write("Starting nodes")
         sys.stdout.flush()
-        rv = all([n.getController().start() for n in self._nodes])
+        rv = all([n.getController().start() for n in self._nodes
+                  if n._env['launch_phase'] ==
+                     self._dfltEnv['CUR_LAUNCH_PHASE']])
         # now print a newline unconditionally - this stops poll()ing
         # output from being squashed together, at the cost of a blank
         # line in wait()ing output