[Bug 1316475] Re: [SRU] CloudSigma DS for causes hangs when serial console present

[Ben Howard]

Proposing backported CloudSigma DS from 14.10 as fixing this issue for
SRU.

** Description changed:

  SRU Justification
  
  Impact: The Cloud Sigma Datasource read and writes to /dev/ttyS1 if
  present; the Datasource does not have a time out. On non-CloudSigma
  Clouds or systems w/ /dev/ttyS1, Cloud-init will block pending a
  response, which may never come. Further, it is dangerous for a default
  datasource to write blindly on a serial console as other control plane
  software and Clouds use /dev/ttyS1 for communication.
  
- Fix: The patch disables Cloud Sigma by default.
+ Fix: The patch queries the BIOS to see if the instance is running on
+ CloudSigma before querying /dev/ttys1.
  
- Verification:
- 1. Purge Cloud-init
- 2. Install from -proposed
- 3. Look in /etc/cloud/cloud.d/90_dpkg.cfg, and confirm CloudSigma is not in the list of datasources. 
+ Verification: On both a CloudSigma instance and non-CloudSigma instance with /dev/ttys1:
+ 1. Install new cloud-init
+ 2. Purge existing cloud-init data (rm -rf /var/lib/cloud)
+ 3. Run "cloud-init --debug init"
+ 4. Confirm that CloudSigma provisioned while CloudSigma datasource skipped non-CloudSigma instance
  
- Regression: The risk is low, except on CloudSigma targets which try to
- use new images generated with the new Cloud-init version.
- 
+ Regression: The risk is low, as this change further restrict where the
+ CloudSigma Datasource can run.
  
  [Original Report]
  DHCPDISCOVER on eth2 to 255.255.255.255 port 67 interval 3 (xid=0x7e777c23)
  DHCPREQUEST of 10.22.157.186 on eth2 to 255.255.255.255 port 67 (xid=0x7e777c23)
  DHCPOFFER of 10.22.157.186 from 10.22.157.149
  DHCPACK of 10.22.157.186 from 10.22.157.149
  bound to 10.22.157.186 -- renewal in 39589 seconds.
   * Starting Mount network filesystems                                    [ OK ]
   * Starting configure network device                                     [ OK ]
   * Stopping Mount network filesystems                                    [ OK ]
   * Stopping DHCP any connected, but unconfigured network interfaces      [ OK ]
   * Starting configure network device                                     [ OK ]
   * Stopping DHCP any connected, but unconfigured network interfaces      [ OK ]
   * Starting configure network device                                     [ OK ]
  
  And it stops there.
  
  I see this on about 10% of deploys.

** Patch added: "Debdiff of backported 14.10 DS"
   https://bugs.launchpad.net/tripleo/+bug/1316475/+attachment/4134540/+files/lp1316475-1303986.deb.diff

** Branch linked:
lp:~utlemming/ubuntu/trusty/cloudinit/lp1316475-1303986

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Title:
  [SRU] CloudSigma DS for causes hangs when serial console present

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