Custom DNS resolution removal

In Vector 0.10.0, we no longer support custom DNS servers. This feature was adding considerable code complexity and is better handled outside of Vector through tools like systemd-resolved.

In the interest of keeping Vector lean and understandable, as well as improving it's maintainability, we've chosen to remove it.

Upgrade Guide

Make the following changes in your vector.toml file:

-  dns_servers = [...]

Enabling DNS outside of Vector

If you were using this feature you may need to configure your host to consult DNS. This can be achieved through tools like systemd-resolved. Alternatively, you can wrap Vector in a container and set the DNS for the container. This can be done via --dns in podman/docker or