add mattermost

examples/mattermost/README.md

@@ -0,0 +1,16 @@
+# References
+
+- https://github.com/mattermost/docker
+- https://docs.mattermost.com/install/install-docker.html
+
+# Notes
+
+The bind volume permissions must be adjusted:
+
+````
+sudo chown -R 2000:2000 /mnt/docker-volumes/mattermost/*
+````
+
+Then rename `env.example` to `.env` and adjust to your needs.
+
+Finally, run `docker compose up` to spawn the container.