fix: raise error if app dest namespace not managed by argocd (#4329)

[jopit]

Signed-off-by: John Pitman jpitman@redhat.com

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• Either (a) I've created an enhancement proposal and discussed it with the community, (b) this is a bug fix, or (c) this does not need to be in the release notes.
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[codecov-commenter]

Codecov Report

Merging #4352 into master will increase coverage by 0.01%.
The diff coverage is 81.81%.

@@            Coverage Diff             @@
##           master    #4352      +/-   ##
==========================================
+ Coverage   42.81%   42.82%   +0.01%     
==========================================
  Files         124      124              
  Lines       18430    18444      +14     
==========================================
+ Hits         7890     7899       +9     
- Misses       9523     9527       +4     
- Partials     1017     1018       +1     

Impacted Files	Coverage Δ
util/argo/argo.go	74.27% <81.81%> (+0.31%)	⬆️
server/application/application.go	30.25% <0.00%> (-0.10%)	⬇️

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[alexmt]

Thanks for working on it @jopit !

Couple edge cases are not taken into account in this PR:

The target application namespace is used as the default namespace. If resource namespace is explicitly specified in manifest stored in git then the resource will be created in that namespace.

Starting 1.7 the namespace field is optional. All application resources might have "hard-coded" namespace or application might include only cluster level resource.

I think the namespace check should be performed in GetManagedLiveObjs method:

https://github.com/argoproj/gitops-engine/blob/c04f859da9b2038b3ad1913be6589858d6311a0a/pkg/cache/cluster.go#L667

We need to validate namespace for each item of targetObjs []*unstructured.Unstructured parameter.

[jopit]

As this is the wrong fix, I will close this PR.