History

mwiegand 9985ecc56c chore(deploy): cleanup left4me-web hardening + docs for kernel overlayfs Drop MountFlags=shared (the assumption that it propagated fuse mounts to host was incorrect on systemd 257 with ProtectSystem+ReadWritePaths). Restore PrivateTmp=true (was dropped in `593611e` for fuse propagation that did not work). Rewrite the comment block to describe the new model: mounts go through the left4me-overlay helper which nsenters into PID 1's mount namespace, so the unit's mount-ns layout is no longer load-bearing. Update the three user-facing READMEs (root, l4d2host, deploy) to drop fuse-overlayfs / fusermount3 prereqs and call out the kernel overlayfs mount path through the privileged helper. Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>		2026-05-08 12:29:49 +02:00
..
files	chore(deploy): cleanup left4me-web hardening + docs for kernel overlayfs	2026-05-08 12:29:49 +02:00
templates/etc/left4me	feat(deploy): add production-like test deployment	2026-05-06 19:30:10 +02:00
tests	chore(deploy): cleanup left4me-web hardening + docs for kernel overlayfs	2026-05-08 12:29:49 +02:00
deploy-test-server.sh	chore(deploy): drop fuse-overlayfs apt dep + one-shot migrate upper/work	2026-05-08 12:28:00 +02:00
README.md	chore(deploy): cleanup left4me-web hardening + docs for kernel overlayfs	2026-05-08 12:29:49 +02:00

README.md

left4me Deployment

This directory contains the production-like test deployment for a Linux server. It installs the repository into a fixed host layout, configures a dedicated runtime user, installs systemd units, and wires the web app to host operations through privileged helper commands.

Target Layout

The deployment uses these paths:

/etc/left4me/host.env: host library environment configuration.
/etc/left4me/web.env: web app environment configuration.
/opt/left4me/.venv: Python virtual environment for deployed commands.
/opt/left4me: deployed repository contents.
/var/lib/left4me/left4me.db: SQLite database used by the web app.
/var/lib/left4me/installation: shared L4D2 installation.
/var/lib/left4me/overlays: overlay directories. Each overlay lives at ${overlay_id} under here.
/var/lib/left4me/workshop_cache: deduplicated cache of .vpk files downloaded for workshop overlays. One file per Steam item, named {steam_id}.vpk. Workshop overlays symlink into this tree.
/var/lib/left4me/global_overlay_cache: cache of non-Steam map archives and extracted .vpk files used by managed global map overlays.
/var/lib/left4me/instances: rendered instance specifications and per-instance state.
/var/lib/left4me/runtime: per-instance runtime mount directories.
/var/lib/left4me/tmp: temporary files used by deployment/runtime operations.
/usr/local/lib/systemd/system: global systemd unit files, including left4me-server@.service.
/usr/local/libexec/left4me: privileged helper commands, including left4me-systemctl, left4me-journalctl, and left4me-overlay (the latter mounts the per-instance kernel overlay in PID 1's mount namespace via nsenter).
/etc/sudoers.d/left4me: sudoers rules allowing the web/runtime commands to call the helpers non-interactively.

Static units are generated for /var/lib/left4me. If LEFT4ME_ROOT changes, regenerate and reinstall the unit files instead of reusing the existing static units.

Runtime User

The deployment creates and runs host operations as the dedicated runtime user:

Username: left4me
Home: /var/lib/left4me
Shell: /usr/sbin/nologin

Running A Test Deployment

Run the deployment from the repository root:

deploy/deploy-test-server.sh deploy-user@example-host

The SSH user must be able to run sudo on the target host. The deployment configures system packages, directories, environment files, helper scripts, sudoers rules, Python dependencies, and systemd units.

Scheduled Jobs

left4me-refresh-global-overlays.timer runs daily with Persistent=true. It invokes flask refresh-global-overlays, which only enqueues a refresh_global_overlays job; downloads and rebuilds run in the web worker and are visible in the normal job log UI.

Admin Bootstrap

Set the bootstrap credentials in the environment when creating the first admin user:

LEFT4ME_ADMIN_USERNAME=admin \
LEFT4ME_ADMIN_PASSWORD='change-me' \
flask create-user "$LEFT4ME_ADMIN_USERNAME" --admin

Use a strong one-time password and rotate it after first login if needed.

Overlay References

Overlay references are relative paths below ${LEFT4ME_ROOT}/overlays. With the default deployment root, they resolve under /var/lib/left4me/overlays. New overlays use ${overlay_id} as their path; the digit-only form is the only one created by the web app.

Invalid references are rejected:

Absolute paths such as /srv/overlay.
Parent traversal such as ../other or competitive/../../base.
Empty path components such as competitive//base.
Symlink escapes that resolve outside ${LEFT4ME_ROOT}/overlays.

The web app currently supports two overlay surfaces:

workshop overlays (user-owned) — populated by downloading .vpk files from the public Steam Web API into ${LEFT4ME_ROOT}/workshop_cache/{steam_id}.vpk and creating absolute symlinks under ${LEFT4ME_ROOT}/overlays/{overlay_id}/left4dead2/addons/{steam_id}.vpk.
Managed global overlays (l4d2center_maps, cedapug_maps, system-wide) — populated by the daily left4me-refresh-global-overlays job, which downloads archives into ${LEFT4ME_ROOT}/global_overlay_cache/ and symlinks them into the overlay directory.

Both the caches and the overlay directories are owned by the left4me runtime user; if the web service ever runs as a different uid, ensure it shares a group with the host process and that both trees are group-readable.