We will be enabling IPv6 support for the agent.buildkite.com domain used by the Buildkite Agent on 2024-11-20. In dual-stack¹ environments, this may mean that agents start connecting from IPv6 addresses where they previously used only IPv4.

If you:

• Have agents running on a dual-stack network, AND
• Use Cluster tokens that restrict agent connection by IP address,

you should ensure that your tokens' IP allowlists include your agents' IPv6 address range(s).

¹ An environment where both IPv4 and IPv6 may be used on the public Internet.