feat: Headless Argo CD (aka GitOps Agent)

[alexmt]

Signed-off-by: Alexander Matyushentsev AMatyushentsev@gmail.com

Summary

PR makes it possible to use argocd CLI commands in a headless mode with Kubectl access only and without Argo CD API server using --headless flag. So it is possible to run argocd app list --headless without logging to Argo CD assuming that current kubecontext points argocd namespace.

The second commit of the PR adds argocd admin dashboard command that starts Argo CD UI locally.

Why?

This change enables two use cases.

1. Argo CD admins have full access to Argo CD settings either way but still have to set up an admin account to manage settings. Instead, we can suggest using argocd --headess CLI to manage all Argo CD settings using only Kubectl access.

2. Argo CD provides awesome features like SSO, RBAC for multi-tenant environments. At the same time, some users who don't need multi-tenancy view these features as a disadvantage and consider Argo CD too heavyweight. That is not correct because of Argo CD UI/API/SSO part is totally optional. Using the argocd --headless flag we can offer Headless Argo CD that consists only of the backend (controller + repo-server).

Long story short:

kubectl create ns argocd
kubectl apply -k ./manifests/base/config
kubectl apply -k ./manifests/crds
kubectl apply -k ./manifests/base/application-controller -n argocd
kubectl apply -k ./manifests/base/redis -n argocd
kubectl apply -k ./manifests/base/repo-server  -n argocd
# done!
argocd login --headless
argocd app create guestbook --repo https://github.com/argoproj/argocd-example-apps --path guestbook --dest-name in-cluster --dest-namespace default --project default

[codecov]

Codecov Report

Merging #6361 (7a75ac1) into master (b627435) will decrease coverage by 0.10%.
The diff coverage is 8.33%.

@@            Coverage Diff             @@
##           master    #6361      +/-   ##
==========================================
- Coverage   41.00%   40.90%   -0.11%     
==========================================
  Files         156      157       +1     
  Lines       20872    20921      +49     
==========================================
- Hits         8558     8557       -1     
- Misses      11101    11151      +50     
  Partials     1213     1213              

Impacted Files	Coverage Δ
cmd/argocd-util/commands/app.go	31.30% <0.00%> (ø)
cmd/argocd-util/commands/cluster.go	0.00% <0.00%> (ø)
cmd/argocd/commands/admin.go	0.00% <0.00%> (ø)
cmd/argocd/commands/login.go	2.31% <0.00%> (-0.12%)	⬇️
cmd/argocd/commands/root.go	2.08% <0.00%> (-0.10%)	⬇️
util/kube/portforwarder.go	0.00% <0.00%> (ø)
util/localconfig/localconfig.go	3.09% <ø> (ø)
server/server.go	53.57% <18.60%> (-1.39%)	⬇️
util/settings/settings.go	47.77% <60.00%> (+0.40%)	⬆️
util/helm/cmd.go	29.87% <0.00%> (-0.37%)	⬇️
... and 2 more

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[mayzhang2000]

Should this be argocd login instead of argo login?

[alexmt]

good catch. Thank you! fixed

[mayzhang2000]

Do we want to break out of this for loop once we found a pod?

[alexmt]

thank you! fixed

[mayzhang2000]

LGTM

[mauricio-sardinas]

The documentation shows the use of /shared/app folder for custom styles, which is being defined with the staticassets flag. If this is not the correct approach what are the alternatives for custom-styling?

https://argoproj.github.io/argo-cd/operator-manual/custom-styles/