From 7678d348fb9337e20adeaaed47d47e28e5108dd5 Mon Sep 17 00:00:00 2001
From: "Daniel Silverstone (br7vm)" <daniel.silverstone@codethink.co.uk>
Date: Fri, 17 May 2013 12:55:04 +0000
Subject: EXTS: simple-network.configure

Simple networking configuration extension, taking NETWORK_CONFIG
from the environment and writing /etc/network/interfaces out during
deployment configuration.
---
 morphlib/exts/simple-network.configure | 143 +++++++++++++++++++++++++++++++++
 1 file changed, 143 insertions(+)
 create mode 100755 morphlib/exts/simple-network.configure

(limited to 'morphlib/exts/simple-network.configure')

diff --git a/morphlib/exts/simple-network.configure b/morphlib/exts/simple-network.configure
new file mode 100755
index 00000000..b98b202c
--- /dev/null
+++ b/morphlib/exts/simple-network.configure
@@ -0,0 +1,143 @@
+#!/usr/bin/python
+# Copyright (C) 2013  Codethink Limited
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; version 2 of the License.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License along
+# with this program; if not, write to the Free Software Foundation, Inc.,
+# 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+
+'''A Morph deployment configuration extension to handle /etc/network/interfaces
+
+This extension prepares /etc/network/interfaces with the interfaces specified
+during deployment.
+
+If no network configuration is provided, eth0 will be configured for DHCP
+with the hostname of the system.
+'''
+
+
+import os
+import sys
+import cliapp
+
+import morphlib
+
+
+class SimpleNetworkError(morphlib.Error):
+    '''Errors associated with simple network setup'''
+    pass
+
+
+class SimpleNetworkConfigurationExtension(cliapp.Application):
+    '''Configure /etc/network/interfaces
+
+    Reading NETWORK_CONFIG, this extension sets up /etc/network/interfaces.
+    '''
+
+    def process_args(self, args):
+        network_config = os.environ.get(
+            "NETWORK_CONFIG", "lo:loopback;eth0:dhcp,hostname=$(hostname)")
+
+        self.status(msg="Processing NETWORK_CONFIG=%(nc)s", nc=network_config)
+
+        stanzas = self.parse_network_stanzas(network_config)
+        iface_file = self.generate_iface_file(stanzas)
+
+        with open(os.path.join(args[0], "etc/network/interfaces"), "w") as f:
+            f.write(iface_file)
+
+    def generate_iface_file(self, stanzas):
+        """Generate an interfaces file from the provided stanzas.
+
+        The interfaces will be sorted by name, with loopback sorted first.
+        """
+
+        def cmp_iface_names(a, b):
+            a = a['name']
+            b = b['name']
+            if a == "lo":
+                return -1
+            elif b == "lo":
+                return 1
+            else:
+                return cmp(a,b)
+
+        return "\n".join(self.generate_iface_stanza(stanza)
+                         for stanza in sorted(stanzas, cmp=cmp_iface_names))
+
+    def generate_iface_stanza(self, stanza):
+        """Generate an interfaces stanza from the provided data."""
+
+        name = stanza['name']
+        itype = stanza['type']
+        lines  = ["auto %s" % name, "iface %s inet %s" % (name, itype)]
+        lines += ["    %s %s" % elem for elem in stanza['args'].items()]
+        lines += [""]
+        return "\n".join(lines)
+
+
+    def parse_network_stanzas(self, config):
+        """Parse a network config environment variable into stanzas.
+
+        Network config stanzas are semi-colon separated.
+        """
+
+        return [self.parse_network_stanza(s) for s in config.split(";")]
+
+    def parse_network_stanza(self, stanza):
+        """Parse a network config stanza into name, type and arguments.
+
+        Each stanza is of the form name:type[,arg=value]...
+
+        For example:
+                   lo:loopback
+                   eth0:dhcp
+                   eth1:static,address=10.0.0.1,netmask=255.255.0.0
+        """
+        elements = stanza.split(",")
+        lead = elements.pop(0).split(":")
+        if len(lead) != 2:
+            raise SimpleNetworkError("Stanza '%s' is missing its type" %
+                                     stanza)
+        iface = lead[0]
+        iface_type = lead[1]
+
+        if iface_type not in ['loopback', 'static', 'dhcp']:
+            raise SimpleNetworkError("Stanza '%s' has unknown interface type"
+                                     " '%s'" % (stanza, iface_type))
+
+        argpairs = [element.split("=", 1) for element in elements]
+        output_stanza = { "name": iface,
+                          "type": iface_type,
+                          "args": {} }
+        for argpair in argpairs:
+            if len(argpair) != 2:
+                raise SimpleNetworkError("Stanza '%s' has bad argument '%r'"
+                                         % (stanza, argpair.pop(0)))
+            if argpair[0] in output_stanza["args"]:
+                raise SimpleNetworkError("Stanza '%s' has repeated argument"
+                                         " %s" % (stanza, argpair[0]))
+            output_stanza["args"][argpair[0]] = argpair[1]
+
+        return output_stanza
+
+    def status(self, **kwargs):
+        '''Provide status output.
+
+        The ``msg`` keyword argument is the actual message,
+        the rest are values for fields in the message as interpolated
+        by %.
+
+        '''
+
+        self.output.write('%s\n' % (kwargs['msg'] % kwargs))
+
+SimpleNetworkConfigurationExtension().run()
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