GDK: Introduce dnsmasq service

Overview

Workspaces requires the usage of wildcard domains. /etc/hosts does not support wildcard domains. This issue proposes that we introduce a dnsmasq service in gdk.yml which will allow us to configure *.workspaces.gdk.test and workspaces.gdk.test to the appropriate listen address of the Workspaces HTTP server in GitLab Agent Server.

Out of scope for this issue but related

• This dnsmasq service can be used by other GitLab components like GitLab Pages for configuring wildcard domains. (https://gitlab.com/gitlab-org/gitlab/-/blob/master/doc/development/pages/dnsmasq.md)
• it would be great to have all routing for GDK be configure through this dnsmasq service. No one would need to make any manual entries in /etc/hosts and it would make setting up GDK easier. But I can understand why some people would hesitate for this.

Impacted categories

The following categories relate to this issue:

• gdk-reliability - e.g. When a GDK action fails to complete.
• gdk-usability - e.g. Improvements or suggestions around how the GDK functions.
• gdk-performance - e.g. When a GDK action is slow or times out.