daemon: Add a startup service.

When enabled, the startup service ensures that other node services
start in order (according to the service _startindex value) and that
the prior service completes before the next service starts.  It also
captures any output from startup commands in a file named
'startup.log'.

daemon/core/services/__init__.py

@@ -3,4 +3,4 @@
 Services available to nodes can be put in this directory.  Everything listed in
 __all__ is automatically loaded by the main core module.
 """
-__all__ = ["quagga", "nrl", "xorp", "bird", "utility", "security", "ucarp", "dockersvc"]
+__all__ = ["quagga", "nrl", "xorp", "bird", "utility", "security", "ucarp", "dockersvc", 'startup']

daemon/core/services/startup.py

@@ -0,0 +1,37 @@
+from core.service import CoreService, addservice
+from sys import maxint
+from inspect import isclass
+
+class Startup(CoreService):
+    'A CORE service to start other services in order, serially'
+    _name = 'startup'
+    _group = 'Utility'
+    _depends = ()
+    _dirs = ()
+    _configs = ('startup.sh', )
+    _startindex = maxint
+    _startup = ('sh startup.sh', )
+    _shutdown = ()
+    _validate = ()
+
+    @staticmethod
+    def isStartupService(s):
+        return isinstance(s, Startup) or \
+            (isclass(s) and issubclass(s, Startup))
+
+    @classmethod
+    def generateconfig(cls, node, filename, services):
+        if filename != cls._configs[0]:
+            return ''
+        script = '#!/bin/sh\n' \
+                 '# auto-generated by Startup (startup.py)\n\n' \
+                 'exec > startup.log 2>&1\n\n'
+        for s in sorted(services, key = lambda x: x._startindex):
+            if cls.isStartupService(s) or len(str(s._starttime)) > 0:
+                continue
+            start = '\n'.join(s.getstartup(node, services))
+            if start:
+                script += start + '\n'
+        return script
+
+addservice(Startup)