feat: added K8s CronJob implementation

[d7oc]

This PR implements #12.

[d7oc]

@xoxys How should we deal with cronLog. This setting is no more needed with this PR as the logs of the CronJob execution will be found in K8s.

[xoxys]

Drop it I would say.

[xoxys]

I'm not that convinced by the huge include block for the env vars. Wouldn't be using a ConfigMap cleaner if we need to share all env vars with other containers?

[d7oc]

I'm not that convinced by the huge include block for the env vars. Wouldn't be using a ConfigMap cleaner if we need to share all env vars with other containers?

We could switch to the ConfigMap (or Secret in here), but the pure amount will still be the same. I'm also not quite sure if there won't be any conflict between the still existing overwrite.config.php and the new file which we will place there build from the config map. I see parameters like those https://github.com/owncloud-docker/base/blob/62d4e7ff12f79fd3a02b17ab6fdca432605ca870/latest/overlay/etc/templates/config.php#L25-L31 which would be set empty as there is no check upfront. So there might be a race condition if I'm right. What we might try is to place the config map "on top" the overwrite.config.php with an overlay mount. I'm just not sure if this works. Needs a test.

So in a nutshell the template approach sounds simpler to me.

[xoxys]

That's not what I was talking about. The idea was to just use a ConfigMap to properly share the env vars by using envFrom.configMapRef, see https://kubernetes.io/docs/tasks/configure-pod-container/configure-pod-configmap/#configure-all-key-value-pairs-in-a-configmap-as-container-environment-variables

[d7oc]

Ah this. Ok this might work. Will give it a try.

[d7oc]

Done, also tested working on a local OpenShift cluster, please recheck.

[xoxys]

How is crondEnabled intended to be used? Right now, cronjobs can't be disabled, right?

[d7oc]

How is crondEnabled intended to be used? Right now, cronjobs can't be disabled, right?

You're right, this was missing, good catch. Added in c85c92d.