6

How can I create and enable permanent 1GB swap file with salt stack that will work after reboot? salt.states.mount.swap does not allow to define swap size. Furthermore I need to define swappiness. Currently I do it with echo vm.swappiness = 10 | sudo tee -a /etc/sysctl.conf

igo
  • 393
  • 4
  • 9

4 Answers4

8

This is what I use on debian-based systems. It's an improved version of Dan's answer. It gets the available memory from a grain, multiplies it by 2, to create the swapfile with the appropriate size. It also makes an entry in /etc/fstab, if non-existent.

coreutils:
  pkg.installed

/swapfile:
  cmd.run:
    - name: |
        [ -f /swapfile ] || dd if=/dev/zero of=/swapfile bs=1M count={{ grains["mem_total"] * 2 }}
        chmod 0600 /swapfile
        mkswap /swapfile
        swapon -a
    - unless:
      - file /swapfile 2>&1 | grep -q "Linux/i386 swap"
  mount.swap:
    - persist: true
Kiril Momchilov
  • 81
  • 1
  • 3
  • 1
    Works on Arch Linux as well. – Cedric Meury Apr 25 '16 at 13:44
  • Note: `swapon -a` probably doesn't do a lot as long as it isn't present in fstab Note2: You might want to check free disk space before creating potentially large files – Marki Feb 16 '21 at 19:10
  • Note3: I'm not sure `* 2` works just like that because computations inside yaml don't work AFAIK – Marki Feb 16 '21 at 19:33
5

I currently use this in production, works for me.

community_swap_file:
  cmd.run:
    - name: |
        [ -f /.swapfile ] || dd if=/dev/zero of=/.swapfile bs=1M count=2048
        chmod 0600 /.swapfile
        mkswap /.swapfile
        echo '/.swapfile      none      swap     sw       0       0' >> /etc/fstab
        swapon -a
    - unless: file /.swapfile 2>&1 | grep -q "Linux/i386 swap"
Dan Garthwaite
  • 2,962
  • 1
  • 19
  • 31
  • Note: the "unless" grep is broken on Ubuntu 22, it should be looking for `Linux swap file` as the output is `/.swapfile: Linux swap file, 4k page size, little endian (...)`, if this isn't changed this will always fire, returning `mkswap: error: /.swapfile is mounted`, adding a new line in `fstab` etc. I'd recommend changing `unless` to just do `test -f /.swapfile` and remove `[ -f /.swapfile ]` from the `name` block – pzkpfw Jun 03 '22 at 09:48
4

Using fallocate is instantaneous compared to dd. Also, the state below will regenerate the swapfile if you change its size in the pillar. This version also omits the superfluous swapon -a, which mount.swap handles for you.

{% set swapfile = salt['pillar.get']('swapfile', {}) %}
{% set size = swapfile.get('size', grains["mem_total"]) %}
{% set path = swapfile.get('path', '/var/swapfile0') %}

{{ path }}:
  cmd.run:
    - name: |
        swapon --show=NAME --noheadings | grep -q "^{{ path }}$" && swapoff {{ path }}
        rm -f {{ path }}
        fallocate -l {{ size }}M {{ path }}
        chmod 0600 {{ path }}
        mkswap {{ path }}
    - unless: bash -c '[[ $(($(stat -c %s {{ path }}) / 1024**2)) = {{ size }} ]]'

  mount.swap:
    - persist: true
Gabriel Totusek
  • 141
  • 1
0

I'm doing a similar thing to Dan's answer:

configuring_swap:
  cmd.run:
    - name: |
        [ -f /var/swap.1 ] && swapoff /var/swap.1
        dd if=/dev/zero of=/var/swap.1 bs=1M count=3072
        chmod 0600 /var/swap.1
        mkswap /var/swap.1
        swapon /var/swap.1
    - unless:
      - "[ `free -b | awk '/Swap/{print $2}'` -ge 3221225472 ]"
  file.append:
    - name: /etc/fstab
    - text: /var/swap.1  swap  swap  defaults  0 0
    - onlyif:
      - file /var/swap.1 2>&1 | grep -q "Linux/i386 swap"

This looks at how much total swap the system has, if it's less than 3GB create a 3GB swap file and make sure it is persistent between reboots via /etc/fstab. If you want to make sure your swappiness config is put in place you can do something like:

configure_swappiness:
  file.append:
    - name: /etc/sysctl.conf
    - text: vm.swappiness = 10
codybuell
  • 11
  • 1
  • 4