I think the easiest solution would be to remove the tty10 destination from the default config altogether, which is maintained by the debian maintainers.

In order to do that, please file a bug to the syslog-ng package.

On Tue, Feb 16, 2021, 03:34 John Kristoff <jtk@dataplane.org> wrote:
I ran into the exact problem succinctly and completely written up here:

  <https://www.claudiokuenzler.com/blog/988/syslog-ng-lxc-container-no-space-left-on-device-dev>

It doesn't appear this was brought to the attention of the devs nor an
issue even filed in github.  I'd like to make sure I didn't miss
something, so posting here for comment before I submit a github issue.

In summary, LXC sets up a small number of tty devices by default.
However, syslog-ng in Debian has this config statement:

  destination d_console_all { file(`tty10`); };

This results in syslog-ng writing the a new /dev/tty10 file instead of
to a device, which will pretty quickly fill up an LXC /dev partition,
causing syslog-ng to soon start failing when it sees the device
associated with tty10 file handle full.

I have modified my syslog-ng.conf directly to use tty2 as the blog
post suggested, but it would be nice if there was a "cleaner"
work-around in the future.

John
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