App Deployer

App Deployer

Deploy and manage user applications (Node.js apps, Python scripts, Go binaries, Docker-less containers, etc.) as first-class managed processes on the OS.

Deploy Workflow

1. Understand — Ask what to deploy. Determine the command, working directory, environment variables, and resource requirements.
2. Deploy — Use app_deploy with appropriate parameters. Default isolation uses DynamicUser=yes (ephemeral UID, no root).
3. Verify — Use app_list to confirm the app is running. Check app_logs for startup output.
4. Store — Use memory_store to remember what was deployed and why.

Example

User: "Deploy my Node.js API at /home/user/api"

1. app_deploy({
     name: "user-api",
     command: "/usr/bin/node",
     args: ["server.js"],
     working_dir: "/home/user/api",
     env: { NODE_ENV: "production", PORT: "3000" },
     port: 3000,
     memory_max: "256M",
     user: "user"
   })
2. app_list() → confirm running, check PID
3. app_logs({ name: "user-api", lines: 20 }) → verify startup
4. memory_store({ summary: "Deployed user-api Node.js app", ... })

Managing Apps

• Status: app_list shows all apps with live systemd state, PID, memory, CPU usage
• Logs: app_logs pulls from journald — supports --since, --priority, line limits
• Restart: app_restart — if the unit is active, calls systemctl restart. If inactive, re-deploys from registry
• Stop: app_stop — stops the unit, marks as stopped in registry (preserved for restart)
• Remove: app_remove — stops and permanently deletes from registry

Resource Limits

Apps run under systemd cgroups. Available limits:

Isolation

• Default (DynamicUser=yes): App runs as an ephemeral system user. No root, no access to other users' files. Best for self-contained binaries and services.
• Named user (user: "username"): App runs as the specified user. Use when the app needs to read/write files owned by that user (e.g., /home/user/data).

Boot Persistence

Apps are registered in /var/lib/osmoda/apps/registry.json. The osmoda-app-restore service re-creates all running apps as transient systemd units on boot. Apps marked as stopped are not restored.

Best Practices

• Always specify memory_max for production apps to prevent OOM issues
• Use port parameter for discovery — system_discover will find the app
• Use named user when the app needs filesystem access beyond its own binary
• Check app_logs after deploy to catch startup errors immediately
• Use app_restart (not stop + deploy) to preserve the same configuration