Code review comment for lp:~thumper/juju-core/no-smash-networking

Reviewers: mp+182248_code.launchpad.net,

Message:
Please take a look.

Description:
Nicer MAAS network change.

The earlier change to create a network bridge for
eth0 was to replace the entire /etc/network/interfaces
file. While this worked, it only worked because MAAS
doesn't yet know much about the network hardware on the
physical machines.

Instead of replacing the entire file, we instead write
out a separate network file and use sed to modify the
existing file to source the new file.

https://code.launchpad.net/~thumper/juju-core/no-smash-networking/+merge/182248

(do not edit description out of merge proposal)

Please review this at https://codereview.appspot.com/13259043/

Affected files:
   A [revision details]
   M environs/maas/environ.go

Index: [revision details]
=== added file '[revision details]'
--- [revision details] 2012-01-01 00:00:00 +0000
+++ [revision details] 2012-01-01 00:00:00 +0000
@@ -0,0 +1,2 @@
+Old revision: tarmac-20130815174953-arsxsn7541v1jxs5
+New revision: <email address hidden>

Index: environs/maas/environ.go
=== modified file 'environs/maas/environ.go'
--- environs/maas/environ.go 2013-08-15 14:13:29 +0000
+++ environs/maas/environ.go 2013-08-16 03:41:38 +0000
@@ -254,11 +254,7 @@
  // createBridgeNetwork returns a string representing the upstart command to
  // create a bridged eth0.
  func createBridgeNetwork() string {
- return `cat > /etc/network/interfaces << EOF
-auto lo
-iface lo inet loopback
-
-auto eth0
+ return `cat > /etc/network/eth0.config << EOF
  iface eth0 inet manual

  auto br0
@@ -268,6 +264,12 @@
  `
  }

+// linkBridgeInInterfaces adds the file created by createBridgeNetwork to
the
+// interfaces file.
+func linkBridgeInInterfaces() string {
+ return `sed -i "s/iface eth0 inet dhcp/source
\/etc\/network\/eth0.config/" etc/network/interfaces`
+}
+
  // internalStartInstance allocates and starts a MAAS node. It is used both
  // for the implementation of StartInstance, and to initialize the bootstrap
  // node.
@@ -314,6 +316,7 @@
    machineConfig,
    runCmd,
    createBridgeNetwork(),
+ linkBridgeInInterfaces(),
    "service networking restart",
   )
   if err != nil {