Mount ConfigMap as JSON file

[chrisjohnson]

What would you like to be added:
In our environment, we use JSON files as the interchange for config rather than a dozen ENV variables. So we fetch and build the config map inside terraform, and then when we go to create a ConfigMap to be given to the pod, we have to first serialize to JSON within terraform so we end up with a ConfigMap that looks like this:

data:
  configuration.json: |
    {"json": "blob"}

It would be great if k8s saw a non-scalar value at data in the manifest, it would first serialize it. How exactly to serialize is not super obvious to me, do you select serialization format based on the key ending in .json? Do you add an attribute to specify how to serialize? Do you always use JSON? Maybe you specify this during the volumeMounts bit? I'm not sure what best fits the overall project.

Why is this needed:
Storing a map as a string in a ConfigMap is icky, it would be nicer if the ConfigMap could just directly house the data as an object and then when it goes to mount in, that's when the conversion happens

[chrisjohnson]

I guessed at the SIG, feel free to re-assign

[kow3ns]

/remove-sig apps

[kow3ns]

/sig node

[kow3ns]

/sig api-machinery

[fedebongio]

/remove-sig api-machinery

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