Add support for different volume types

[skonto]

Feature request

Add support for different volume types. In Serving we have recently added two different volume types: Emptydir and PVCs.

Use case

It would be nice to extend the cli to support volumes. Users can then use the cli to add volumes as they would normally do with
a yaml file when deploying services.

UI Example

This could work similarly to the --extra-containers flag. At minimum users should be able to pass the configuration for volumes
at pod level and at container level via json/yaml data.

If it is found useful defaults could be added. For example if emptydir is used a default volume mount could be done under a predefined dir eg. /cache along with a predefined emptyDir.medium eg. memory.

Examples:

kn service create helloworld-go --image gcr.io/knative-samples/helloworld-go --emptydir-volumes-config json_data
kn service create helloworld-go --image gcr.io/knative-samples/helloworld-go --pvc-volumes-config json_data

{emptydir, pvc}-volumes-config refers to the pod voumes field. Regarding the container volume mounts these can be configured either with an extra parameter eg. --emptydir-volumemounts for the user container and rely on --extra-containers flag for the rest of the mounts targeting other containers. This should be extended in the future to support init-containers too.

/cc @rhuss

[rhuss]

I think it's best to add support for extra volumes to our existing volume support for configmaps and secrets (--volume and --mount). We can extend the value syntax to add more volume specific options like in --volume emptyDir:myVolumeName:type=memory and then --mount /path/to/mount=myVolumeName. This should then also work for multi container ...

[skonto]

Sure I was looking for some existing volume support but it didnt come up in my search.

[vyasgun]

/assign

[vyasgun]

/reopen

[knative-prow]

@vyasgun: Reopened this issue.

In response to this:

/reopen

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[vyasgun]

Reopening this issue as #1679 addresses only half of the requested feature.