[QUESTION] Environment variables in registry config files?

[gyszalai]

Is it possible to use environment variables in k3d and/or registry config files? We have a corporate docker registry that I'd like to use in my local k3d cluster, so I created a registries.yaml with the registry config. I'd like to put this file under version control, but in contains a username and password for this internal registry, so substituted these with environment variable references like this:

auth:
    username: ${REGISTRY_USER}
    password: ${REGISTRY_PASSWORD}

Unfortunately these references don't get resolved when I start my cluster. Am I doing something wrong?

[FedericoAntoniazzi]

Hi @gyszalai, I've just tried setting environment variables in a k3d configuration file and it doesn't work. I looked at the code, environment variables are considered as normal values but, luckily, Viper has full support for them so we just need to implement that feature.

@iwilltry42 I would create an issue from this discussion and reference this in a future PR, are you okay with that?

Reference: Viper - Working with Environment Variables

[iwilltry42]

Hi @FedericoAntoniazzi , thanks for chiming in here.
If the env var expansion in the k3d config file (as of v5) is not sufficient (see my comment below: #761 (comment)), I'd happily accept any PR that adds some value here :)

[iwilltry42]

Hi @gyszalai , thanks for opening this issue!
A solution to this issue depends on how you use the registry config.
In general, that config is used by K3s and k3d doesn't touch it (apart from when it generates it in some use cases).
But, the k3d configuration file supports expanding environment variables as of k3d v5.0.0, so if you use the embedded registry config there, environment variables would be expanded.
Does that work for you?

[gyszalai]

Hi @iwilltry42, thank you, it works! It would be nicer to be able store registry config in a separate file, though.
Is it possible, that resolving env vars in registry config file actually works, but the vars are not passed to the container that runs k3s?

[iwilltry42]

Hey, sorry for getting back to this this late...
k3d only runs the k3d config file through the environment variable expansion function.
The registry config file (if not embedded inside the k3d config) is passed on as-is to the K3s container.
I don't know if K3s would expand environment variables in that file though (would need to ask in https://github.com/k3s-io/k3s) 🤔

but the vars are not passed to the container that runs k3s?

What do you mean? From where should they be passed on? If you need env vars in the K3s containers, you'd specify them via --env or the respective config file option 🤔