Support Use Of Top Level Domains

[0x0D15]

Feature request description

On my LAN, where I control DNS resolution, I often define A records to various LAN IPs without a second domain level for convenience (for example registry). Most utilities, such as web browsers, will function if you navigate to these domains (for example: http://registry) as they are inherintly valid, however Podman/Buildah will incorrectly attempt to search for the domain instead of directly resolving it.

Suggest potential solution

Directly resolve top level domains instead of searching for them. These behavior can either be default or opt-in: I would mainly just like a mechanism to force Podman/Buildah to resolve the top level domain.

[Luap99]

@mtrmac PTAL

I think the ultimate problem is that we allow shortnames that get resolved to a registry so it is impossible to know if repo/name means something like docker.io/repo/name or repo/name where repo is the domain. As such I don't see how we could support that without causing backwards compatibility concerns.

[mtrmac]

Yes, “don”t do that”.

There is a syntactic ambiguity, and I’m very uninterested in making the behavior of such inputs any more ambiguous, or in adding an option to modify handling of such ambiguous inputs. Besides my aesthetic distaste for ambiguity, which matters little — realistically, given the many manual or sort-of-manual parsers around, no change of this type would be consistently implemented throughout the ecosystem for many years, so it would not really help — reliable deployments would need to avoid such DNS names either way.

(There are also other features, like signing, which sort of require a “world-wide identity”, and are not very compatible with DNS setups that conflict with the global DNS namespace. That might not matter right now in this specific deployment, but it’s an important consideration for anyone else who might find this report.)

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With the implemented semantics, the hostname part must contain either a . or a : (or be exactly localhost). So, depending on specifics on the setup, either introduce DNS names that are within a subdomain, or refer to registries using an explicit port, e.g. registry:443/….

[0x0D15]

Defining the default port is probably the ideal workaround for this, thanks. I assume I can even define this as a shortname to essentially get the functionality I want out-of-the-box.

I do find it unfortunate that Podman is the only utility I interact with regularly that is unable to function with top level domains though, seems that everything else works correctly.