hub.deploymentStrategy.type: "Recreate" or "RollingUpdate"

[consideRatio]

@clkao you resolved an issue we got before in #763!

I'm using an external DB and could go for the RollingUpdate deploymentStrategy of the hub. But I'm a bit confused about a comment. Perhaps you could help me out by some insight about this?

  deploymentStrategy:
    # sqlite-pvc backed hub requires Recreate strategy to work
    type: Recreate
    # This is required for upgrading to work
    rollingUpdate: null

1. The note say "for upgrading to work". You are referring to helm chart upgrades here, or is it database upgrades, or either?
2. Why did we need to set that to null? I'd assume those are options only in use during a rollingupdate, and now that I want to use a type: RollingUpdate strategy. I suspect I will need to specify the default explicitly to override the default null value. Should we delete setting that section?

My attempted answer to 2:
It seems from the Helm documentation, that setting a value to null is a way to signal we want to delete a previous value, to do an "unset" operation so to say. From my current understanding, that means it would accomplish nothing as the values in values.yaml of the helm chart are the default values already.

I think it makes sense to delete setting that value.

[clkao]

you are right. previously the default deploymentStrategy brought in some rollingUpdate params by default. with that just changing to Recreate wouldn't work for upgrading. so the comment should have been more explicit: required for upgrading from version X to current. and if we already dropped support for version X, we can definitely get rid of the comment.

[consideRatio]

I messed up in #1401 and then corrected this and add a comment about my conclusions in #1404!