If you notice your Alpine Docker containers giving you a "gpg: keyserver receive failed: Address not available" error and you've only got IPv4, check to make sure your address is set to ipv4.pool.sks-keyservers.net rather than the usual ha.pool.sks-keyservers.net. This one bit me tonight!

Thx to https://github.com/nodejs/docker-node/issues/380#issuecomment-306451705