Helm3 - live session

gistfile1.txt

#Helm is package manager: same kind of apps getting deployed to varous platforms by. various teams with similar configs.
#Helm is templating engine: when most of the app values are same except for image name port helm can prove to be useful.
#Helm hub: https://hub.helm.sh/
#Helm charts GitHub Project: https://github.com/helm/charts
#Helm v3: https://helm.sh/blog/helm-3-released/

curl -sfL https://get.k3s.io | sh -
export KUBECONFIG=/etc/rancher/k3s/k3s.yaml
curl -fsSL -o get_helm.sh https://raw.githubusercontent.com/helm/helm/master/scripts/get-helm-3
chmod 700 get_helm.sh
./get_helm.sh
helm repo add stable https://kubernetes-charts.storage.googleapis.com/
helm search repo stable
helm repo update
helm install stable/grafana --generate-name
kubectl get secret --namespace default grafana-1588446269 -o jsonpath="{.data.admin-password}" | base64 --decode ; echo
helm plugin install https://github.com/instrumenta/helm-kubeval
helm kubeval stable/grafana


helm completion bash

helm --help
helm search repo stable
helm ls 
helm repo list
kubectl create ns traefik
helm install stable/traefik -n traefik --generate-name
helm ls -n traefik

helm create test
helm hub

helm uninstall --keep-history


Upgrades
In Helm 2, it would generate a patch, comparing the old manifest against the new manifest. Because this is a rollback, it's the same manifest. Helm would determine that there is nothing to change because there is no difference between the old manifest and the new manifest. The replica count continues to stay at zero. Panic ensues.

In Helm 3, the patch is generated using the old manifest, the live state, and the new manifest. Helm recognizes that the old state was at three, the live state is at zero and the new manifest wishes to change it back to three, so it generates a patch to change the state back to three.