helm list : cannot list configmaps in the namespace "kube-system"

Helm runs with "default" service account. You should provide permissions to it.

For read-only permissions:

kubectl create rolebinding default-view --clusterrole=view --serviceaccount=kube-system:default --namespace=kube-system

For admin access: Eg: to install packages.

kubectl create clusterrolebinding add-on-cluster-admin --clusterrole=cluster-admin --serviceaccount=kube-system:default

The default serviceaccount does not have API permissions. Helm likely needs to be assigned a service account, and that service account given API permissions. See the RBAC documentation for granting permissions to service accounts: https://kubernetes.io/docs/admin/authorization/rbac/#service-account-permissions

Once these commands:

kubectl create serviceaccount --namespace kube-system tiller
kubectl create clusterrolebinding tiller-cluster-rule --clusterrole=cluster-admin --serviceaccount=kube-system:tiller
kubectl patch deploy --namespace kube-system tiller-deploy -p '{"spec":{"template":{"spec":{"serviceAccount":"tiller"}}}}'      
helm init --service-account tiller --upgrade

were run, the issue has been solved.

More Secure Answer

The accepted answer gives full admin access to Helm which is not the best solution security wise. With a little more work, we can restrict Helm's access to a particular namespace. More details in the Helm documentation.

$ kubectl create namespace tiller-world
namespace "tiller-world" created
$ kubectl create serviceaccount tiller --namespace tiller-world
serviceaccount "tiller" created

Define a Role that allows Tiller to manage all resources in tiller-world like in role-tiller.yaml:

kind: Role
apiVersion: rbac.authorization.k8s.io/v1
metadata:
  name: tiller-manager
  namespace: tiller-world
rules:
- apiGroups: ["", "batch", "extensions", "apps"]
  resources: ["*"]
  verbs: ["*"]

Then run:

$ kubectl create -f role-tiller.yaml
role "tiller-manager" created

In rolebinding-tiller.yaml,

kind: RoleBinding
apiVersion: rbac.authorization.k8s.io/v1
metadata:
  name: tiller-binding
  namespace: tiller-world
subjects:
- kind: ServiceAccount
  name: tiller
  namespace: tiller-world
roleRef:
  kind: Role
  name: tiller-manager
  apiGroup: rbac.authorization.k8s.io

Then run:

$ kubectl create -f rolebinding-tiller.yaml
rolebinding "tiller-binding" created

Afterwards you can run helm init to install Tiller in the tiller-world namespace.

$ helm init --service-account tiller --tiller-namespace tiller-world

Now prefix all commands with --tiller-namespace tiller-world or set TILLER_NAMESPACE=tiller-world in your environment variables.

More Future Proof Answer

Stop using Tiller. Helm 3 removes the need for Tiller completely. If you are using Helm 2, you can use helm template to generate the yaml from your Helm chart and then run kubectl apply to apply the objects to your Kubernetes cluster.

helm template --name foo --namespace bar --output-dir ./output ./chart-template
kubectl apply --namespace bar --recursive --filename ./output -o yaml