Kubernetes: one-off env exec

Problem statement: run an one-off script and/or binary within a kubernetes pod. It needs a certain environment variable (VAULT_TOKEN) to be set. Wrong: shell ubuntu@my-deploy-server:~ $ kubectl exec -n vault vault-1 -- VAULT_TOKEN=hvs.mysupersecrettoken vault read auth/kubernetes/role/vault-init error: Internal error occurred: Internal error occurred: error executing command in container: failed to exec in container: failed to start exec "7455bd5880fe41c177a47702e3dfacbe4240...