Creating a node on WSL fails in disable-swap.yml

[sirredbeard]

Provisioning a node on WSL fails when attempting to disable swap in the pf9-express playbook:

- name: Disable swap
  command: swapoff -a
  when: ansible_swaptotal_mb > 0

Results in:

TASK [disable-swap : Disable swap] *************************************************************************************
Tuesday 05 January 2021  11:32:54 -0500 (0:00:00.223)       0:00:04.179 ******* 
fatal: [localhost]: FAILED! => {"changed": true, "cmd": ["swapoff", "-a"], "delta": "0:00:00.001871", "end": "2021-01-05 11:32:54.833778", "msg": "non-zero return code", "rc": 255, "start": "2021-01-05 11:32:54.831907", "stderr": "", "stderr_lines": [], "stdout": "", "stdout_lines": []}

This is because running sudo swapoff -a $? results in:

$ sudo swapoff -a $?
swapoff: 255: swapoff failed: No such file or directory

This is because even though there is no swap mounted in /etc/fstab:

$ cat /etc/fstab
LABEL=cloudimg-rootfs   /        ext4   defaults        0 0

Swap is provided by the WSL2 VM shared between all running WSL distros:

$ cat /proc/swaps
Filename                                Type            Size    Used    Priority
/swap/file                              file            7340032 0       -2

The official way to disable swap on WSL2 is to set swap=off in %USERPROFILE%/.wslconfig.

The workaround for now is to simply comment out that step in the disable-swap role.

As discussed in #111 it can be tricky to detect if you are running in WSL, but it is possible.

There is a use case for being able to run a node on WSL for dev training purposes so it still may be worth addressing.

My first idea is to use a block here in the playbook to execute sudo swapoff -a with a rescue: that if cat /proc/version | grep -q 'microsoft' it will still then pass.

[sarun87]

@sirredbeard Using sudo swapoff -a with a rescue to set .wslconfig file works for now. We can do this to unblock WSL installs for now. Let me know if you plan to open up a PR for the same.

[sirredbeard]

@sarun87

Disabling swap in .wslconfig will disable swap for all WSL containers, not just the one being attached as a node. I would suggest, if conditions are met (swapoff -a fails but WSL is true):

• A prompt notifying the user that this change is being made to .wslconfig, confirming they want to make the change, and advising they will need to restart WSL with wsl.exe --shutdown before provisioning their node
• In addition to making the change, make a backup of their original .wslconfig for the user as %USERPROFILE%\wslconfig.bak

If this sounds okay, I will work on it soon.

We can do this to unblock WSL installs for now.

Note that running pf9ctl on WSL still requires a systemd script for now.