Initial hotplug support (#936)

Adds a udev script which will invoke a hotplug hook script on all net
add events. The script will write some udev arguments to a systemd FIFO
socket (to ensure we have only instance of cloud-init running at a
time), which is then read by a new service that calls a new 'cloud-init
devel hotplug-hook' command to handle the new event.

This hotplug-hook command will:
- Fetch the pickled datsource
- Verify that the hotplug event is supported/enabled
- Update the metadata for the datasource
- Ensure the hotplugged device exists within the datasource
- Apply the config change on the datasource metadata
- Bring up the new interface (or apply global network configuration)
- Save the updated metadata back to the pickle cache

Also scattered in some unrelated typing where helpful

1 files changed, 4 insertions, 1 deletions

diff --git a/bash_completion/cloud-init b/bash_completion/cloud-init
index a9577e9d..b9f137b1 100644
--- a/bash_completion/cloud-init
+++ b/bash_completion/cloud-init
@@ -28,7 +28,7 @@ _cloudinit_complete()
                     COMPREPLY=($(compgen -W "--help --tarfile --include-userdata" -- $cur_word))
                     ;;
                 devel)
-                    COMPREPLY=($(compgen -W "--help schema net-convert" -- $cur_word))
+                    COMPREPLY=($(compgen -W "--help hotplug-hook schema net-convert" -- $cur_word))
                     ;;
                 dhclient-hook)
                     COMPREPLY=($(compgen -W "--help up down" -- $cur_word))
@@ -64,6 +64,9 @@ _cloudinit_complete()
                 --frequency)
                     COMPREPLY=($(compgen -W "--help instance always once" -- $cur_word))
                     ;;
+                hotplug-hook)
+                    COMPREPLY=($(compgen -W "--help" -- $cur_word))
+                    ;;
                 net-convert)
                     COMPREPLY=($(compgen -W "--help --network-data --kind --directory --output-kind" -- $cur_word))
                     ;;