feat: add support for configuring runner worker root device name

[charlesbjohnson]

trafficstars

Description

These changes add support for configuring the root device name for the Docker Machine instances. This is necessary when using an Amazon Linux AMI where the default device name of /dev/sda1 ends up creating a 2nd, unused, non-root volume.

https://docs.aws.amazon.com/AWSEC2/latest/UserGuide/device_naming.html#available-ec2-device-names

---

---

---

---

Migrations required

No, considering the default value of the variable

Verification

Confirmed root device on Docker Machine instances is correctly configured in both fleet-mode and non-fleet mode when using an AL2 AMI

[github-actions[bot]]

Hey @charlesbjohnson! 👋

Thank you for your contribution to the project. Please refer to the contribution rules for a quick overview of the process.

Make sure that this PR clearly explains:

• the problem being solved
• the best way a reviewer and you can test your changes

With submitting this PR you confirm that you hold the rights of the code added and agree that it will published under this LICENSE.

The following ChatOps commands are supported:

• /help: notifies a maintainer to help you out

Simply add a comment with the command in the first line. If you need to pass more information, separate it with a blank line from the command.

This message was generated automatically. You are welcome to improve it.

[kayman-mk]

Moved the images to a separate issue to get a cleaner commit message (as the whole PR description is used as commit message).