I've previously installed tiller into a specific namespace.
I set an environment variable to set the 'tiller' namespace - but I can't remember what this environment variable was called - and can't seem to find it via a web search.
What is this key?
By executing helm -h you can see the list of environment variables it uses:
Environment:
$HELM_HOME set an alternative location for Helm files. By default, these are stored in ~/.helm
$HELM_HOST set an alternative Tiller host. The format is host:port
$HELM_NO_PLUGINS disable plugins. Set HELM_NO_PLUGINS=1 to disable plugins.
$TILLER_NAMESPACE set an alternative Tiller namespace (default "kube-system")
$KUBECONFIG set an alternative Kubernetes configuration file (default "~/.kube/config")
$HELM_TLS_CA_CERT path to TLS CA certificate used to verify the Helm client and Tiller server certificates (default "$HELM_HOME/ca.pem")
$HELM_TLS_CERT path to TLS client certificate file for authenticating to Tiller (default "$HELM_HOME/cert.pem")
$HELM_TLS_KEY path to TLS client key file for authenticating to Tiller (default "$HELM_HOME/key.pem")
$HELM_TLS_VERIFY enable TLS connection between Helm and Tiller and verify Tiller server certificate (default "false")
$HELM_TLS_ENABLE enable TLS connection between Helm and Tiller (default "false")TILLER_NAMESPACEHelm will look for Tiller in the kube-system namespace unless --tiller-namespace or TILLER_NAMESPACE is set.
https://docs.helm.sh/using_helm#easy-in-cluster-installation