SSH configuration

Kamal uses SSH to connect run commands on your hosts. By default it will attempt to connect to the root user on port 22.

If you are using non-root user, you may need to bootstrap your servers manually, before using them with Kamal. On Ubuntu, you’d do:

shell

sudo apt update
sudo apt upgrade -y
sudo apt install -y docker.io curl git
sudo usermod -a -G docker app

SSH options

The options are specified under the ssh key in the configuration file.

yaml

ssh:

The SSH user

Defaults to root:

yaml

  user: app

The SSH port

Defaults to 22:

yaml

  port: "2222"

Proxy host

Specified in the form <host> or <user>@<host>:

yaml

  proxy: root@proxy-host

Proxy command

A custom proxy command, required for older versions of SSH:

yaml

  proxy_command: "ssh -W %h:%p user@proxy"

Log level

Defaults to fatal. Set this to debug if you are having SSH connection issues.

yaml

  log_level: debug

Set to true to use only private keys from keys and key_data parameters, even if ssh-agent offers more identities. This option is intended for situations where ssh-agent offers many different identities or you have a need to overwrite all identities and force a single one.

yaml

  keys_only: false

Keys

An array of file names of private keys to use for publickey and hostbased authentication:

yaml

  keys: [ "~/.ssh/id.pem" ]

Key data

An array of strings, with each element of the array being a raw private key in PEM format.

yaml

  key_data: [ "-----BEGIN OPENSSH PRIVATE KEY-----" ]