Run an HTTP Server in a VM

This guide shows how to create a Debian virtual machine, install nginx, and expose its HTTP port to the host so you can reach it from a browser or curl.

Create the Virtual Machine

Create a VM with port forwarding so that host port 8080 maps to guest port 80:

$ cubic create webserver --image debian:trixie --port 8080:80

Start the Virtual Machine

$ cubic start webserver

Install nginx

Connect to the VM over SSH and install nginx:

$ cubic ssh webserver
$ sudo apt update && sudo apt install -y nginx

nginx starts automatically after installation and listens on port 80 inside the VM.

Verify from the Host

Open a new terminal on the host and send a request to port 8080:

$ curl http://localhost:8080
<!DOCTYPE html>
<html>
<head>
<title>Welcome to nginx!</title>
...

You can also open http://localhost:8080 in a browser.

Show VM Settings

Use cubic show --all to inspect the full VM configuration including all active port forwarding rules:

$ cubic show --all webserver
Status:       stopped
PID:          n/a
Arch:         amd64
CPUs:         4
Memory:       4.0 GiB
Disk Used:    1.2 GiB
Disk Total:   100.0 GiB
User:         alice
Isolated:     no
SSH Port:     10022
Monitor Port: 10023
Console Port: 10024
Disk Image:   ~/.local/share/cubic/machines/webserver/machine.img
Config:       ~/.local/share/cubic/machines/webserver/instance.toml
SSH Key:      ~/.local/share/cubic/machines/webserver/ssh_client_key
SSH:          ssh -i .../webserver/ssh_client_key -p 10022 alice@localhost
Forward:      127.0.0.1:8080:80/tcp

Modify VM Settings

Port forwarding rules and other VM settings can be changed at any time with cubic modify. Changes take effect on the next restart.

Add a forwarding rule for HTTPS (port 443):

$ cubic modify webserver --port 8443:443

Remove the HTTP forwarding rule:

$ cubic modify webserver --rm-port 8080:80

Increase the number of CPUs and memory:

$ cubic modify webserver --cpus 2 --memory 2G