1205653 - Vagrant: Add workaround for virtualbox shared folders sendfile bug

Status: RESOLVED WONTFIX

(Tree Management :: Treeherder, defect, P2)

Description

[Ed Morley [:emorley]]

Virtualbox has a bug where when using shared folders, the contents of a file transferred using sendfile can sometimes end up corrupted. A ticket for this issue has been open against Virtualbox for three years, but it still remains unfixed:
https://www.virtualbox.org/ticket/9069
https://www.virtualbox.org/ticket/12597

The way this would manifest is:
* file gets served via a sendfile syscall
* file is modified (I think inside the VM? not sure if the same occurs if modified outside the VM)
* file is served again, but is either (a) the old version, (b) a truncated copy of the old version, (c) a longer version of the old version but with garbage appended. (Depends on whether the file length stayed the same or increased/decreased).

There have been reports that this doesn't affect people using NFS.

This vagrant ticket has the workaround, which is to disable sendfile:
https://github.com/mitchellh/vagrant/issues/351#issuecomment-1339640

The Vagrant docs now even mention this issue:
https://docs.vagrantup.com/v2/synced-folders/virtualbox.html

Now since we're using WhiteNoise (and not Apache httpd or Nginx), we'll need to disable in Gunicorn, which is now possible in Gunicorn >= v19.2:
https://github.com/benoitc/gunicorn/commit/2849147f8aeb990c4f55a168e3d32ec2167ca093
https://github.com/benoitc/gunicorn/issues/856

...by using `--no-sendfile` on the CLI:
http://docs.gunicorn.org/en/latest/settings.html#sendfile

We'll want to make sure sendfile is still enabled outside of the Vagrant environment, for stage/prod performance reasons.

Comment 1

[Ed Morley [:emorley]]

Ideally we would be able to disable sendfile via an environment variable, and so avoid having to add complexity to the run_gunicorn script. Filed:
https://github.com/benoitc/gunicorn/issues/1252

Comment 2

[Ed Morley [:emorley]]

In the newly release gunicorn 19.6.0 sendfile can now be disabled by defining `SENDFILE=0` in the environment:
http://docs.gunicorn.org/en/latest/settings.html#sendfile

Comment 3

[Ed Morley [:emorley]]

Wontfix since we're going to move towards docker instead (bug 1169263).