How to ssh in lightsail instance as root?

To log in to your Lightsail instance as the root user, you'll need to follow these steps:

1. Generate a new SSH key pair: You'll need an SSH key pair to connect to your Lightsail instance as the root user. If you haven't already, you can generate a new key pair by following the instructions in the Lightsail console.

2. Assign the SSH key to your instance: In the Lightsail console, go to your instance and click on the "Connect" button. Select the "Connect using SSH" option, and then click on the "Connect" button. This will open a new browser tab with an SSH connection to your instance.

3. Switch to the root user: Once you're connected to your instance, you can switch to the root user by running the following command:

sudo su -

This will switch you to the root user, and you should now be able to perform any administrative tasks on your Lightsail instance.

Note that the su -l root command you mentioned doesn't work because the root user is not enabled by default on Ubuntu-based Lightsail instances. Instead, you need to use the sudo command to elevate your privileges to the root user.

Also, keep in mind that it's generally not recommended to log in as the root user for everyday tasks. Instead, it's better to use the Ubuntu user and escalate privileges using sudo when necessary.