registry.mirror does not support rooted FQDN #2948
Description
/etc/containers/registries.conf.d/099-example.conf with this content:
[[registry]]
prefix = "docker.io"
insecure = false
blocked = false
location = "docker.io"
[[registry.mirror]]
location = "my-mirror.example.com.:5500/"
Causes weird error message:
$ buildah from --pull debian:bullseye-slim
Trying to pull docker.io/library/debian:bullseye-slim...
Error: unable to copy from source docker://debian:bullseye-slim: initializing source docker://debian:bullseye-slim: rewriting reference: invalid reference format
Same issue happens if I use location = "docker.io" in the [[registry]] section.
Rooted FQDN are useful, to skip DNS search list. This especially useful in k8s clusters with search list being very long and with high ndots value in resolve.conf. This not only improves performance (some dns clients might even timeout before finishing whole search) , it also queries less DNS servers and help prevent leaking names to unwanted DNS servers.
$ buildah --version
buildah version 1.41.3 (image-spec 1.1.1, runtime-spec 1.2.1)
on Fefora 42, amd64.
containers-common-0.64.1-2.fc42.noarch
containers-common-extra-0.64.1-2.fc42.noarch
buildah-1.41.3-1.fc42.x86_64
podman-5.6.0-1.fc42.x86_64
From my experience, essentially all tools, libraries and programming languages do support trailing . in domain names and URL. This does include docker too.