Stopped creating kapp app configmap during --diff-run

[sethiyash]

• kapp should not create kapp app configmap while doing any operation with --diff-run flag

[cppforlife]

would recommend blocking merge of this issue on #450

[100mik]

I think we can rebase this on develop now.

[praveenrewar]

I am thinking if the effects of --diff-run should just be limited to creation of ConfigMap or should they also extend to updates as well. For example, if we use --labels x=y, along with --diff-run while updating an app, should these labels be added to the ConfigMap?

[neil-hickey]

I am thinking if the effects of --diff-run should just be limited to creation of ConfigMap or should they also extend to updates as well. For example, if we use --labels x=y, along with --diff-run while updating an app, should these labels be added to the ConfigMap?

I would expect nothing to change on the cluster if I use --diff-run. No configmaps created, no labels added, no changes. So in my mind, the answer to should the labels be added is no.

[kumaritanushree]

LGTM

[sethiyash]

Hi @praveenrewar,
As @neil-hickey correctly pointed out in the case of --diff-run ideally nothing should change on the cluster but currently when there is an update operation and the user do - kapp deploy -a test -f test.yaml --labels x=y --diff-run we are actually updating the configmap with labels even if it's a diff-run.

Please let me know your thoughts on changing this behaviour to not updating the configmap as part of this PR.

[neil-hickey]

Please let me know your thoughts on changing this behaviour to not updating the configmap as part of this PR.

I'd vote for a separate issue / PR. This one should probably remain scoped to just the creation of the configmap.

[neil-hickey]

LGTM

[sethiyash]

After discussion with the team, we have decided to address the update flow as part of this PR only.

[100mik]

No super strong feelings about this one, just a thought

[praveenrewar]

A couple of thoughts I had while taking a look.

• If we are making sure that diff-run doesn't result in any change in the cluster, then we might have to make changes to the UsedGVs and UsedGKs because they will also be updating the ConfigMap.
• Since we will have to make changes in so many places, it might make sense to have the isDiffRun in the RecordedApp itself so that we don't have to pass it along in so many places and use it just when required.
• Another thing that might be worth exploring is if it's possible to have the dry run set for the whole client itself (but I guess that's not possible for the core client).

(I am totally okay with creating a separate PR for the updates)

[praveenrewar]

LGTM!