Allow env var to set a listener.
Allow env var to set a listener.

benoahriz/sidecar,Nitro/sidecar,newrelic/sidecar,newrelic/sidecar,newrelic/sidecar,benoahriz/sidecar,Nitro/sidecar,benoahriz/sidecar,newrelic/sidecar,benoahriz/sidecar,Nitro/sidecar,Nitro/sidecar