On a default Docker install (at least for Debian), Docker will frequently log messages like this:
Jun 11 23:11:18 fmt1 systemd[1]: run-docker-runtime\x2drunc-moby-03e02cea35c5f9bcde0f17bf97a1e9bbddfb6139aafec4ee6d2066c1e2294c2f-runc.hVhGzb.mount: Succeeded.
Jun 11 23:11:18 fmt1 systemd[1099531]: run-docker-runtime\x2drunc-moby-03e02cea35c5f9bcde0f17bf97a1e9bbddfb6139aafec4ee6d2066c1e2294c2f-runc.hVhGzb.mount: Succeeded.
Jun 11 23:11:18 fmt1 systemd[1099531]: run-docker-runtime\x2drunc-moby-eec04ed2b08bd700c2323524b0e47f99d2271911fb55d2fe539353151519841d-runc.diFO9t.mount: Succeeded.
Jun 11 23:11:18 fmt1 systemd[1]: run-docker-runtime\x2drunc-moby-eec04ed2b08bd700c2323524b0e47f99d2271911fb55d2fe539353151519841d-runc.diFO9t.mount: Succeeded.
Jun 11 23:11:18 fmt1 systemd[1099531]: run-docker-runtime\x2drunc-moby-e46ca8dd109d673c1a35d7a6aefd7687c0ba045fc699f5c16c7818e7dc4b9ceb-runc.70pa2l.mount: Succeeded.
Jun 11 23:11:20 fmt1 systemd[1099531]: run-docker-runtime\x2drunc-moby-285e25c21995fcb0c38f68e3a7be049c7d3e73da2e2e206c889555de4b7fa52b-runc.HPLG7u.mount: Succeeded.
Jun 11 23:11:20 fmt1 systemd[1]: run-docker-runtime\x2drunc-moby-285e25c21995fcb0c38f68e3a7be049c7d3e73da2e2e206c889555de4b7fa52b-runc.HPLG7u.mount: Succeeded.
Jun 11 23:11:20 fmt1 systemd[1099531]: run-docker-runtime\x2drunc-moby-75cda4722ece2f7aa6706c825e68bb5f95b27f5b918d1d3510ce99faeae083ea-runc.WsBYoK.mount: Succeeded.
Jun 11 23:11:23 fmt1 systemd[1]: run-docker-runtime\x2drunc-moby-c9ce9db39b96a33fe3e38dbd1777dbb38e6490a1c8b78f87ad3727cb41decd5c-runc.Y1CFhK.mount: Succeeded.
Jun 11 23:11:23 fmt1 systemd[1099531]: run-docker-runtime\x2drunc-moby-c9ce9db39b96a33fe3e38dbd1777dbb38e6490a1c8b78f87ad3727cb41decd5c-runc.Y1CFhK.mount: Succeeded.
Jun 11 23:11:24 fmt1 systemd[1099531]: run-docker-runtime\x2drunc-moby-d563d305b1942c6fa10c10a2ed3a5d036bd0e353fb1dca74dd909fafa458113e-runc.rDap1L.mount: Succeeded.
These messages can be filtered with rsyslogd to prevent them from being exported remotely.
To add a filter to block the messages, create a .cond file in /etc/rsyslog.d. Prepend the file name with a lower number to make sure it is processed before other configuration files. As an example, use the file name 00-ignore-docker-mounts.conf.
The required filters can then be added to the file using the following syntax:
:msg, contains, "run-docker-runtime" stop
:msg, contains, "var-lib-docker-overlay2" stop
An easily copy-pastable way to add the filter:
cat << EOF > /etc/rsyslog.d/00-ignore-docker-mounts.conf
:msg, contains, "run-docker-runtime" stop
:msg, contains, "var-lib-docker-overlay2" stop
EOF
systemctl restart rsyslog