Export bundle returns a broken bundle in Kubernetes

[Dominik Fleischmann]

When using the `juju export-bundle` command on kubernetes, the bundle that is returned is not deployable. When trying to deploy it the following error is returned:
ERROR cannot deploy bundle: cannot add unit for application "minio": adding units to a container-based model not supported (not supported)

Steps to reproduce:
# Juju 2.9.25 controller on microk8s
juju add-model minio
juju deploy minio
juju export-bundle --filename mybundle.yaml
juju destroy-model minio --destroy-storage
juju add-model minio
juju deploy ./mybundle.yaml

The workaround for this is simply adding `series: kubernetes` in the charm section. Therefore while export-bundle returns:

bundle: kubernetes
applications:
  minio:
    charm: minio
    channel: stable
    revision: 57
    resources:
      oci-image: 338
    scale: 1

It should be:

bundle: kubernetes
applications:
  minio:
    charm: minio
    channel: stable
    revision: 57
    series: kubernetes # <- this is missing.
    resources:
      oci-image: 338
    scale: 1

[Heather Lanigan (hmlanigan)]

This looks like a bug in the deploy code, not the export-bundle code.

[Heather Lanigan (hmlanigan)]

The error has changed as of 2.9.27:

juju deploy ./1963249-bundle.yaml
Located charm "minio" in charm-hub, channel stable
Executing changes:
- upload charm minio from charm-hub with revision 57 with architecture=amd64
ERROR cannot deploy bundle: cannot add charm "minio": series required for charm-hub charms (bad request)

[Canonical Juju QA Bot (juju-qa-bot)]

This Medium-priority bug has not been updated in 60 days, so we're marking it Low importance. If you believe this is incorrect, please update the importance.