output public ssh host keys to console on boot (LP: #893400)

Currently cloud-init writes something like this to console output:
  ec2: #############################################################
  ec2: -----BEGIN SSH HOST KEY FINGERPRINTS-----
  ec2: 2048 78:ae:f3:91:04:6f:8d:ee:ef:e1:2d:72:83:6a:d0:82  root@h (RSA)
  ec2: 1024 d3:b6:32:64:22:d4:43:05:f9:25:b4:f3:65:4e:e2:51  root@h (DSA)
  ec2: -----END SSH HOST KEY FINGERPRINTS-----
  ec2: #############################################################

the key fingerprints are useful for humans to read, but not so useful
for machines, as you cannot populate a KnownHostsFile (~/.ssh/known_hosts)
from the data there.

This change adds output like:
  -----BEGIN SSH HOST KEY KEYS-----
  ecdsa-sha2-nistp256 AAAAE2VjZHNhLXNoYTItbmlzdH......STI= root@h
  ssh-rsa AAAAB3NzaC1yc2EAAAADAQABAAABAQDYRIQe6m......tWF3 root@h
  -----END SSH HOST KEY KEYS-----

Those lines can easily be grabbed and appended to a known_hosts file.

LP: #893400

1 files changed, 1 insertions, 0 deletions

diff --git a/ChangeLog b/ChangeLog
index 451800f5..e0cec684 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -10,6 +10,7 @@
    - config change: 'retries' dropped, 'max_wait' added, timeout increased
  - close stdin in all cloud-init programs that are launched at boot (LP: #903993)
  - revert management of /etc/hosts to 0.6.1 style (LP: #890501, LP: #871966)
+ - write full ssh keys to console for easy machine consumption (LP: #893400)
 0.6.2:
  - fix bug where update was not done unless update was explicitly set.
    It would not be run if 'upgrade' or packages were set to be installed