Difference between --from-env-file single vs multiple

[shaktiprasadrath]

This is a Bug Report

If --from-env-file with multiple file will ONLY take the last file then why we have this option. this is as good as --from-env-file from a single file.

Proposed Solution:
There should be an option to take --from-env-file from multiple files.

Page to Update:
https://kubernetes.io/...

1.1.13

[christophercarney]

Page referenced: https://kubernetes.io/docs/tasks/configure-pod-container/configure-pod-configmap/#create-configmaps-from-files

I agree this is confusing for users as the documentation does mention it in passing as if it is a feature but it is actually supposed to be a warning.

Proposed Solution: Adjust the wording to make it clear that this is a warning rather than a feature

@shaktiprasadrath You may want to open this issue in https://github.com/kubernetes/kubectl but I believe the correct pattern would be to create separate config maps for each file so they can remain independent

@sftim thoughts?

[sftim]

The page states:

You can pass in the --from-file argument multiple times to create a ConfigMap from multiple data sources.

I have not tried this, TBH. It sounds like kubectl ought to warn people if --from-file is specified more than once (that'd be a separate issue against kubectl).

If kubectl doesn't have that warning but kinda should, then the documentation should have a warning instead. IMO.

[christophercarney]

It looks like the distinction then is between --from-file and --from-env-file. For the latter:

When passing --from-env-file multiple times to create a ConfigMap from multiple data sources, only the last env-file is used

So it looks like the --from-file is the more robust preferred option, but --from-env-file may be supported for legacy reasons, but I'd have to confirm.

The way they populate the config map is also different in a subtle way which may also need clarifying

[aimeeu]

/priority important-soon

[lapwat]

As I understood:

--from-file loads filename:filecontent as a unique key:value pair
--from-env-file loads each line (formatted as KEY=value) as key:value pairs

So --from-env-file is not legacy. It is a way to load a set of environment variables.

I think it is a good behavior to be able to load a unique env file.

Proposed Solution:
There should be an error if --from-env-file option is used more than once in the same command.

[sftim]

To request an enhancement to kubectl, visit https://github.com/kubernetes/kubectl/issues/new/choose and file an issue. It's OK to reference the URL of this issue: #16729