SSHKit

SSHKit is the SSH toolkit used by Kamal.

The default, settings should be sufficient for most use cases, but when connecting to a large number of hosts, you may need to adjust.

SSHKit options

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

sshkit:

Max concurrent starts

Creating SSH connections concurrently can be an issue when deploying to many servers. By default, Kamal will limit concurrent connection starts to 30 at a time.

  max_concurrent_starts: 10

Pool idle timeout

Kamal sets a long idle timeout of 900 seconds on connections to try to avoid re-connection storms after an idle period, such as building an image or waiting for CI.

  pool_idle_timeout: 300