What is LabCaptain ?

LabCaptain is a tiny daemon + CLI tool that helps to deploy lab environment in cluster.

Why LabCaptain ?

I have planned to build a lab environment or dev platform first. Then thought about this abstraction layer which will help to build and deploy lab environment easily. So, I decided to build this lightweight tool to manage it.

The name LabCaptain is due to the fact that it takes the responsibility of lab environment management. You will just say it you need to deploy a lab environment for certain period of time and it will do the task.

Now, the most interesing part is -

1. Labcaptain project is providing a docker base image, so that you can build your own lab environment easily.

   FROM registry.hub.docker.com/tanmoysrt/labcaptain_base
   
   # Write your own configuration

2. Simple API to manage lab environment.
3. Web terminal, code server, VNC, port forwarding is pre-configured out of the box.
   • https://terminal-{lab_id}.example.com : Web terminal
   • https://editor-{lab_id}.example.com : Code server (VSCode like)
   • https://vnc-{lab_id}.example.com : VNC
   • https://port-{port_no}.{lab_id}.example.com : Port forwarding out of the box. You can run your own tool inside the container and access it via the url format. Just small restrictions - you cant use 8000, 8001, 8002, 8003, 8004 ports.

To know more, how can you disable specific feature like VNC, check the image documentation. https://hub.docker.com/r/tanmoysrt/labcaptain_base

Tech Stack

• Golang
• SQLite3 (for database)
• Podman
• Prometheus (for monitoring)
• HAProxy
• NoVNC + noVNC proxy
• ttyd

System Architecture

Lab Architecture (Labcaptain Docker Image)

Installation guide (Ubuntu 22.04)

Caution

Before we procced, remember these points.

• Your lab deployment lab server doesn't receive incoming traffice directly from internet, Only your LabCaptain server or management server receives the traffic.
• So, you must use firewall to block incoming traffic from internet to your lab server except the traffic which is coming from your LabCaptain server or management server.
• If you are hosting all the servers in same cloud provider, consider to create a private network and assign public IP to your LabCaptain server. It can communicate with your lab server via private IPs.

Configure SSH Agent

• Generate a ssh private key for all of your other servers (if you haven't already)

  ssh-keygen -t rsa -b 4096 -C "[email protected]"

  Put the private key in /root/.ssh/id_rsa and the public key in /root/.ssh/id_rsa.pub
• Create/edit /etc/rc.local file and add the following line

  #!/bin/sh -e
  
  eval $(ssh-agent)
  ssh-add /root/.ssh/id_rsa
  exit 0

  and make that file executable with chmod +x /etc/rc.local and reboot the server.
• That's it.

1. Install golang (https://go.dev/doc/install)
2. Clone the repo
3. Go inside labcaptain folder
4. Run go build to build the binary
5. Move the labcaptain binary to /usr/local/bin
6. Run labcaptain local-setup to setup labcaptain on the local machine
7. Run labcaptain server add <ip> to add a new server
8. Run labcaptain server list to list all servers
9. Run labcaptain server setup-podman <ip> to setup podman on the server
10. Run labcaptain server setup-prometheus <ip> to setup prometheus exporter on the server
11. Run labcaptain server enable <ip> to enable a server
12. Create a systemd service file /etc/systemd/system/labcaptain.service like this

[Unit]
Description=LabCaptain
After=network.target

[Service]
WorkingDirectory="<provide_a_path_here_to_store_labcaptain_data>"
User=root
Type=simple
Environment="LAB_CAPTAIN_BASE_DOMAIN=example.com"
Environment="LABCAPTAIN_API_TOKEN=random_secret"
ExecStartPre=/bin/bash -c 'ssh-agent -s | grep -E "SSH_AUTH_SOCK|SSH_AGENT_PID" > /tmp/ssh-agent.env && source /tmp/ssh-agent.env && ssh-add /root/.ssh/id_rsa'
ExecStart=/bin/bash -c 'source /tmp/ssh-agent.env && /usr/local/bin/labcaptain start'
Restart=always
RestartSec=10

[Install]
WantedBy=multi-user.target

13. Run systemctl daemon-reload and systemctl enable labcaptain
14. Run systemctl start labcaptain to start labcaptain

API Documentation

1. Deploy a lab

• Method: POST
• URL: http://localhost:8888/start
• Body:

  {
    "image": "registry.hub.docker.com/tanmoysrt/labcaptain_base:1",
    "expiry_time": "2024-09-21T13:04:05Z",
    "web_terminal_enabled": true,
    "code_server_enabled": true,
    "vnc_enabled": true,
    "port_proxy_enabled": true,
    "environment_variables": ""
  }

• Response:

  {
    "id": "tqtw1fl7ku2imcp",
    "status": "requested",
    "expiry_time": "2024-01-01T00:00:00Z"
  }

2. Get lab status

• Method: GET
• URL: http://localhost:8888/status/:lab_id
• Response:

  {
    "id": "tqtw1fl7ku2imcp",
    "status": "provisioned",
    "expiry_time": "2024-01-01T00:00:00Z"
  }

3. Stop a lab

• Method: POST
• URL: http://localhost:8888/stop/:lab_id
• Response:

  Lab destroyed successfully
  

  If you got 200 OK, it means the lab is destroyed successfully.

Future Work

• Implement SSH connection pool for faster communication
• Implement support for resource limits
• Configurable option for lab proxy at port 443 ssl (P.S : currently it's also possible by editing labcaptain/nginx.conf.template)
• Remote storage mount support

License

MIT License

Credits

Special thanks to these projects

• https://github.com/ConSol/docker-headless-vnc-container (Apache License 2.0). It made it possible to have proper configuration for Xfce4 + noVNC setup for headsup.
• https://github.com/tsl0922/ttyd (MIT License). It made it possible to have a web terminal.
• https://github.com/coder/code-server (MIT License). It made it possible to have a code server.