systemd

Running Comis as a systemd service on Linux

systemd is the standard way to run background services on Linux. Setting up Comis as a systemd service means it starts automatically when your server boots, restarts if it crashes, and integrates with standard Linux monitoring tools.

systemd is Linux only. If you are on macOS, use pm2 instead.

Two paths

You can get a systemd-managed Comis daemon two ways:

Recommended: the one-line installer. The script at https://comis.ai/install.sh creates the comis system user, lays out /etc/comis, writes a managed comis.service unit, sets up sudoers rules so the service user can start/stop/restart its own daemon without root, and starts everything. This is the path the official VPS install guide uses.

curl -fsSL https://comis.ai/install.sh | bash

The installed unit file is checksum-tagged with # managed-by: comis-installer. If you edit it by hand, the installer will refuse to overwrite it on upgrade — so manual edits stick around.

Manual: the steps below. Use this when you need a unit file under your own control (different paths, different hardening, different user). The rest of this page walks through that.

Prerequisites

Before setting up the systemd service, make sure you have:

• Node.js 22 or newer installed on your server
• Comis built — run pnpm build in the Comis directory
• A dedicated system user for running Comis (created in step 1 below)

Setup

1. Create a system user

   Create a dedicated comis user that has no login shell. This is a security best practice — the daemon runs under its own user with limited permissions.

   sudo useradd -r -s /sbin/nologin comis
   

   The -r flag creates a system user (no home directory, no login). The -s /sbin/nologin flag prevents anyone from logging in as this user.

2. Install Comis

   Copy your built Comis files to a system directory and create the data directory:

   sudo mkdir -p /opt/comis
   sudo cp -r . /opt/comis/
   sudo mkdir -p /var/lib/comis
   sudo chown -R comis:comis /opt/comis /var/lib/comis
   

   • /opt/comis/ — where the application code lives (read-only at runtime)
   • /var/lib/comis/ — where the database, logs, and runtime data are stored (read-write)
3. Create the configuration

   Create a directory for the config file and environment variables:

   sudo mkdir -p /etc/comis
   sudo cp ~/.comis/config.yaml /etc/comis/config.yaml
   sudo chown comis:comis /etc/comis/config.yaml
   sudo chmod 600 /etc/comis/config.yaml
   

   Create the environment file at /etc/comis/env with your API keys and config path:

   sudo tee /etc/comis/env > /dev/null << 'EOF'
   COMIS_CONFIG_PATHS=/etc/comis/config.yaml
   ANTHROPIC_API_KEY=your-api-key-here
   EOF
   sudo chmod 600 /etc/comis/env
   sudo chown comis:comis /etc/comis/env
   

   Keep API keys in the environment file rather than in config.yaml. The environment file has strict permissions (readable only by the comis user) and is not tracked in version control.

4. Install the service file

   Create the systemd unit file at /etc/systemd/system/comis.service:

   [Unit]
   Description=Comis AI Agent Daemon
   Documentation=https://github.com/comis/comis
   After=network-online.target
   Wants=network-online.target
   
   [Service]
   Type=exec
   User=comis
   Group=comis
   WorkingDirectory=/opt/comis
   
   # --jitless: Disable JIT to reduce attack surface (no W^X pages)
   # --permission: Enable Node.js permission model for filesystem restrictions
   ExecStart=/usr/bin/node --jitless --permission \
     --allow-fs-read=/opt/comis \
     --allow-fs-write=/var/lib/comis \
     --allow-child-process dist/daemon.js
   
   # Restart policy
   Restart=on-failure
   RestartSec=5s
   
   # Shutdown: allow 45s for graceful shutdown (app timeout is 30s)
   TimeoutStopSec=45
   
   # Resource limits
   MemoryMax=2G
   TasksMax=100
   
   # Standard output/error to journald for structured log collection
   StandardOutput=journal
   StandardError=journal
   SyslogIdentifier=comis
   
   # Environment
   Environment=NODE_ENV=production
   EnvironmentFile=-/etc/comis/env
   
   # --- Security Hardening ---
   
   # Filesystem protection
   ProtectSystem=strict
   ProtectHome=yes
   PrivateTmp=yes
   ReadWritePaths=/var/lib/comis /var/log/comis
   
   # Memory protection
   MemoryDenyWriteExecute=yes
   
   # Privilege escalation prevention
   NoNewPrivileges=yes
   
   # Drop all capabilities
   CapabilityBoundingSet=
   
   # System call filtering: allow only standard service calls
   SystemCallFilter=@system-service
   SystemCallArchitectures=native
   
   # Kernel and device protection
   PrivateDevices=yes
   ProtectKernelTunables=yes
   ProtectKernelModules=yes
   ProtectKernelLogs=yes
   ProtectControlGroups=yes
   ProtectClock=yes
   ProtectHostname=yes
   RestrictRealtime=yes
   RestrictSUIDSGID=yes
   RestrictNamespaces=yes
   LockPersonality=yes
   
   [Install]
   WantedBy=multi-user.target
   

   --permission also disables fd-based fs APIs (fsync, fchmod, fchown) at the daemon-process level. Credential file writes are best-effort durability (no fsync) and file permissions are best-effort. This is guarded at all call sites — the daemon will not crash — but the tradeoff is documented in Node Permissions — Production fd-API Disablement.

   Then reload systemd to pick up the new file:

   sudo systemctl daemon-reload
   
5. Start the service

   Enable the service (so it starts on boot) and start it immediately:

   sudo systemctl enable --now comis
   

   Expected output:

   Created symlink /etc/systemd/system/multi-user.target.wants/comis.service -> /etc/systemd/system/comis.service.
   
6. Verify it is running

   Check the service status:

   sudo systemctl status comis
   

   You should see output similar to:

   ● comis.service - Comis AI Agent Daemon
        Loaded: loaded (/etc/systemd/system/comis.service; enabled)
        Active: active (running) since ...
      Main PID: 12345 (node)
        Status: "Comis daemon started"
         Tasks: 12 (limit: 100)
        Memory: 150.0M (max: 2.0G)
   

   The key indicators are:

   • Active: active (running) — the daemon is running
   • Status: “Comis daemon started” — the daemon completed its startup sequence

Service file explained

Here is what each important section of the unit file does:

Type=exec

systemd considers the service started once execve() returns. In-process liveness is observed by Comis’s ProcessMonitor (event loop delay tracking) and surfaced on the /health HTTP endpoint; crash recovery is handled by Restart=on-failure below. Comis does not participate in the systemd liveness-ping protocol — operators who require kernel-level watchdog integration can add it via a systemd drop-in.

Restart=on-failure + RestartSec=5s

If the daemon crashes (exits with a non-zero code), systemd waits 5 seconds and then starts it again automatically. This covers unexpected errors, out-of-memory kills, and unhandled exceptions. Normal stops (via systemctl stop) do not trigger a restart.

MemoryMax=2G + TasksMax=100

Resource limits prevent the daemon from consuming too many system resources. If memory exceeds 2 GB, systemd kills the process (which then triggers a restart). TasksMax limits the number of threads and processes the daemon can create.

Node.js —permission flags

The --permission flag enables the Node.js permission model, which restricts what the daemon can access:

• --allow-fs-read=/opt/comis — can read application code only from /opt/comis
• --allow-fs-write=/var/lib/comis — can write data only to /var/lib/comis
• --allow-child-process — can spawn child processes (needed for some tools)

This acts as a second layer of security, even if a vulnerability is exploited.

See Node Permissions — Production fd-API Disablement for the impact of --permission on daemon-process fd-based APIs (fsync, fchmod, fchown).

EnvironmentFile=-/etc/comis/env

Loads environment variables (like API keys and COMIS_CONFIG_PATHS) from the specified file. The - prefix means systemd will not fail if the file is missing — it simply skips loading it.

Security hardening directives

The bottom section of the unit file locks down the service:

Directive	What it does
ProtectSystem=strict	Makes the entire filesystem read-only except explicitly allowed paths
ProtectHome=yes	Hides all home directories from the service
NoNewPrivileges=yes	Prevents the daemon from gaining elevated permissions
MemoryDenyWriteExecute=yes	Blocks creating memory that is both writable and executable
SystemCallFilter=@system-service	Only allows system calls needed for normal services
PrivateDevices=yes	Hides physical devices from the service

Browser tool wiring (when installed with --with-browser / --with-xvfb / --with-cloakbrowser)

The browser-tool flags don’t change the security posture — they widen specific write paths just enough for the chosen browser binary to launch:

Install flag	ReadWritePaths additions	--allow-fs-write additions
--with-browser (stock Chrome)	~/.config/google-chrome, ~/.local/share/applications, ~/.config/comis/browser	Same set; mirrored on the Node permission model
--with-cloakbrowser (stealth Chromium)	~/.cloakbrowser, ~/.config/chromium, ~/.config/comis/browser	Same; tighter than the Chrome variant (no mimeapps write needed — CloakBrowser patches that out)
--with-xvfb	(no extra paths — see companion unit below)	(no extra paths)

Every additional write path is named, scoped to the daemon’s home, and matches what the binary actually writes. The Chrome variant needs ~/.local/share/applications for mimeapps.list (Chrome’s default-browser registration; no flag disables it). The cloak variant doesn’t.

comis-xvfb.service companion (when installed with --with-xvfb)

A second managed unit at /etc/systemd/system/comis-xvfb.service runs Xvfb on display :99 as the same comis user:

[Service]
ExecStart=/usr/bin/Xvfb :99 -screen 0 1920x1080x24 -ac -nolisten tcp

-nolisten tcp keeps the X server on a Unix socket only; -ac is safe because the socket is owned by the comis user and inaccessible from outside that namespace. The main comis.service unit picks up the display by way of three additional directives:

After=network-online.target comis-xvfb.service
Wants=network-online.target comis-xvfb.service
Environment=DISPLAY=:99
JoinsNamespaceOf=comis-xvfb.service

JoinsNamespaceOf= is load-bearing — without it, PrivateTmp=yes on the main unit gives the daemon its own /tmp namespace and the X11 socket at /tmp/.X11-unix/X99 is unreachable. The pair share /tmp for exactly this purpose.

Manage the companion unit the same way as the main one:

sudo systemctl status comis-xvfb         # check it's running
sudo systemctl restart comis-xvfb        # bounces both this and the daemon
journalctl -u comis-xvfb --since "-1h"   # Xvfb startup logs

The companion is uninstalled together with the main service by bash install.sh --uninstall (no separate command needed).

Common commands

Command	What it does
sudo systemctl start comis	Start the daemon
sudo systemctl stop comis	Stop the daemon (waits up to 45 seconds for graceful shutdown)
sudo systemctl restart comis	Stop and start the daemon
sudo systemctl status comis	Show current status, PID, memory, and recent log lines
sudo systemctl enable comis	Start automatically on boot
sudo systemctl disable comis	Do not start on boot

Viewing logs

systemd sends all daemon output to the journal. Use journalctl to view logs:

Live logs (follow mode):

journalctl -u comis -f

Recent logs (last hour):

journalctl -u comis --since "1 hour ago"

Logs since last boot:

journalctl -u comis -b

Only errors and warnings:

journalctl -u comis -p err

The daemon also writes logs to ~/.comis/logs/daemon.log (resolved against the service user’s home — /var/lib/comis/.comis/logs/daemon.log for an installer-managed service). See Logging for details on configuring log levels and rotation.

Related pages

Daemon

How the daemon starts, runs, and shuts down.

pm2

Alternative process manager for macOS and Linux.

Docker

Run Comis in a Docker container.

Logging

Configure log levels, rotation, and structured output.

Troubleshooting

Solutions to common issues.