consider global kapp-controller flag to raise default sync period

[cppforlife]

Describe the problem/challenge you have By default sync period is 30s on App CRs. It might be useful for an administrator to set higher default syncPeriod.

Describe the solution you'd like

• add --app-default-sync-period=X flag on kapp-controller (defaulted to 30s)
• add --app-minimum-sync-period=X flag as well (defaulted to 30s)
• add --package-install-default-sync-period=X flag as well (defaulted to 5m)

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[danielhelfand]

Think this would be a good addition. For anyone picking up this issue, a good place to start might be looking at the flags for the controller here.

[joe-kimmel-vmw]

@danielhelfand @cppforlife the suggestion above to look at the flags is helpful but i think not the full story.

The other end of the change imo is that this hardcoded30 wants to be read from some global-state store.

Off the top of my head I can't think of prior art for something like this, though maybe I'm forgetting something. Where could we keep information that we can access from the ReconcileTimer (or maybe via its .app)? ... e.g. could we use os.SetEnv to write it at initialization time and then look it up when we're in the reconcile timer? or could we add it to the kcconfig, and if so how is that available from the ReconcileTimer?

[joe-kimmel-vmw]

TODO: reach out to users (proactively reach out to internal users, TKG, other users welcome to comment on this ticket). to see the personas of who is setting the config: https://github.com/vmware-tanzu/carvel-kapp-controller/blob/develop/pkg/config/config.go#L38 vs. the deployment flags, to see if there's a more or less reasonable place to put these additional knobs.

[aaronshurley]

I had a brief chat with @shyaamsn about this and he expressed a preference for the ability to set these properties via the config. The reasons being that it would align with how they currently configure things and it would be easier to track changes.

[aaronshurley]

To consolidate some updates on this issue:

• v0.26.0 changed the default sync periods to 10m from 30s (release notes). So, the urgency for this issue has been reduced but it would still be helpful to expose this for users to customize.
• We would like to provide expose this configuration via the config.
• The property names could still be ironed out, feel free to discuss this here or in Slack.

[cppforlife]

closing for now. will reopen if we need to provide more configurability to admins.