content/hints/pm-utils-ubuntu-vagrant-fun.rst

   1 Using pm-utils to save/restore VMs on workstation suspend/restore
   2 #################################################################
   3
   4 :date: 2017-09-16
   5 :tags: hints,ubuntu,vagrant,pm
   6 :category: hints
   7 :author: Jude N
   8
   9 I use Ubuntu (16.04 for now) and Vagrant (1.9.0 for now) on a bunch of my projects, and I've been running into somethinng like this
  10 `power management bug` for a while now, where after restoring from suspension, my vagrant sessions would be dead and I'd have to
  11 'vagrant halt' and 'vagrant up' before another 'vagrant ssh' would succeed.
  12
  13 To work around this, I came up with some /etc/pm/sleep.d scripts which would save any running vagrant boxes when suspending the
  14 workstation and then resume the VMs when resuming the workstation.
  15
  16 Now if I'm in a 'vagrant ssh' session and Ubuntu suspends/resumes, instead of coming back to a frozen session, I'll see I've been
  17 disconnected from the ssh session, and I can do another 'vagrant ssh' without having to halt/re-up the VM.  That's better than nothing,
  18 but the next step here is to start using something like screen or tmux in my vagrant sessions so I can restore right back to where I left
  19 off.
  20
  21 So why bother with two scripts when you could have 1 script with a single case statement ?  I wanted saving the running vagrant boxes to
  22 happen when all the usual services and userspace infrastructure was still running, so I wanted that script in the 00 -49 range from as
  23 per the 'Sleep Hook Ordering Convention' portion of 'man 8 pm-action`.    However I don't restoration to happen until all the services
  24 restarted, so I pushed to the end of the service handling hook range.  I may want to revisit this, and rename it to 75_vagrant.
  25
  26 Note in the resume script, the command is pushed into the background since I didn't want want to wait for the VMs to be restored before
  27 resuming Ubuntu.  I'm usually checking email or the web for a bit before going back to my VMs so I'm OK if that's ready immediately.
  28
  29 Here are some other lessons I learned from these scripts:
  30
  31 - I didn't know `vagrant global-status`_ existed !
  32 - vagrant commands have to be run as the user started the VM.  I had to use runuser to run the vagrant commands as my dev user.
  33 - I learned the '-I %' approach of `getting xargs to insert it's argument in the middle of a command`_.
  34
  35 The first script is /etc/pm/sleep.d/01_vagrant:
  36
  37 .. code-block:: bash
  38
  39    #!/bin/bash
  40
  41    YOURNAME="your normal nonroot user name"
  42
  43    case "$1" in
  44        suspend)
  45            timestamp=`date --rfc-3339=seconds`
  46            echo "${timestamp}: $0 output" >> /var/log/pm-suspend-vagrant.log
  47            (/sbin/runuser -u ${YOURNAME} /usr/bin/vagrant global-status | grep running | awk '{ print $1; }' | xargs -L1 -I % runuser -u ${YOURNAME} vagrant suspend % ) >> /var/log/pm-suspend-vagrant.log
  48            ;;
  49        *)
  50            ;;
  51    esac
  52
  53    # Don't let errors above stop suspension
  54    true
  55
  56 The second script is /etc/pm/sleep.d/74_vagrant.sh
  57
  58 .. code-block:: bash
  59
  60     #!/bin/bash
  61
  62     YOURNAME="your normal nonroot user name"
  63
  64     case "$1" in
  65          resume)
  66             # Push the restoration into the background so it doesn't slow down
  67             timestamp=`date --rfc-3339=seconds`
  68             ((/sbin/runuser -u ${YOURNAME} /usr/bin/vagrant global-status | grep saved | awk '{ print $1; }' | xargs -L1 -I % runuser -u ${YOURNAME} vagrant resume % ) >> /var/log/pm-resume-vagrant.log) &
  69             ;;
  70         *)
  71             ;;
  72     esac
  73
  74     # Don't let errors above stop restoration
  75     true
  76
  77 Sources:
  78 - http://manpages.ubuntu.com/manpages/xenial/man8/pm-action.8.html
  79
  80 .. _power management bug: https://www.virtualbox.org/ticket/15378
  81 .. _vagrant global-status: https://www.vagrantup.com/docs/cli/global-status.html
  82 .. _getting xargs to insert it's argument in the middle of a command: https://stackoverflow.com/a/40355248/496127