[Bug 1668327] Re: Startup scripts get run when guest packages are updated

[Philip Roche]

gce-compute-image-packages version 20160930-0ubuntu6~16.04.0 in xenial-
proposed has been verified.

For reference attached testplan was used for verification.

** Attachment added: "gce-compute-image-packages-xenial-testplan-proposed.txt"
   https://bugs.launchpad.net/ubuntu/+source/gce-compute-image-packages/+bug/1668327/+attachment/4843449/+files/gce-compute-image-packages-xenial-testplan-proposed.txt

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https://bugs.launchpad.net/bugs/1668327

Title:
  Startup scripts get run when guest packages are updated

Status in gce-compute-image-packages package in Ubuntu:
  Fix Released
Status in gce-compute-image-packages source package in Trusty:
  Fix Committed
Status in gce-compute-image-packages source package in Xenial:
  Fix Committed
Status in gce-compute-image-packages source package in Yakkety:
  Fix Committed
Status in gce-compute-image-packages source package in Zesty:
  Fix Released

Bug description:
  [Impact]

   * This bug affects: Zesty, Yakkety, Xenial and Trusty

   * When a user upgrades to a newer version of gce-cimpute-image-packages 
     then the google-startup-scripts service is run which causes any configured
     startup scripts to be executed. 

   * Running these scripts more than once on a running instance is not exptected 
     behaviour and depending on the contents of the user's scripts could have 
     disastrous consequences. 

   * The fix tis to use override_dh_systemd_start in the debian/rules to alter the 
     generated postinst, prerm and postrm files to not restart the startup or 
     shutdown scripts on upgrade or install. 

  [Test Case]

   * Start instance with shutdown script and startup script

  gcloud compute instances create ubuntu-1604-xenial-v20170224 --image-project ubuntu-os-cloud 
  --image "ubuntu-1604-xenial-v20170224"  --metadata shutdown-script="#! /bin/bash
  touch /home/ubuntu/shutdown.txt",startup-script="#! /bin/bash 
  touch /home/ubuntu/startup.txt"

  # Run the following on the running instance 
  # clean up instance ready for testing

  rm -f ~/startup.txt

  # Add new PPA with fixed package

  sudo add-apt-repository -y ppa:philroche/gce-compute-image-packages
  sudo apt-get update
  sudo apt-get install --only-upgrade gce-compute-image-packages

  # Note that the first upgrade will always result in shutdown 
  # scripts being run as the initial gce-compute-image-packages postrm script are still in use.  
  # verify that the bug still exists

  if [ -f ~/shutdown.txt ]; then
      echo "Shutdown File found! Bug still present"
      rm -f ~/shutdown.txt
  fi

  [Regression Potential]

   * Possible regressions are that the startup and shutdown script services never start and user's scripts to not get 
   executed. This has been tested and is not the case.

  [Original bug description]
   

  A user reported (https://github.com/GoogleCloudPlatform/compute-image-
  packages/issues/376) that startup scripts are running when the guest
  packages get updated on Ubuntu. This can of course have very
  unexpected consequences.

  I did some digging and found that the postinst you are using is not
  the same as ours and appears to start all the systemd services
  including startup and shutdown scripts when it runs.

  if [ -d /run/systemd/system ]; then
          systemctl --system daemon-reload >/dev/null || true
          deb-systemd-invoke start google-accounts-daemon.service google-clock-skew-daemon.service google-instance-setup.service google-ip-forwarding-daemon.service google-network-setup.service google-shutdown-scripts.service google-startup-scripts.service >/dev/null || true

  We have a postinst that works on other systemd platforms which you are
  welcome to use or mimic here: https://github.com/GoogleCloudPlatform
  /compute-image-
  packages/blob/master/google_compute_engine_init/systemd/postinst.sh

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