I create the secret ok as file, but podman secret create secret_name --env=true $env_name fails.

When I create the secret as file, no matter whether it is JSON or simple variable='thing', when I create the container using the command 

Podman run -dit --secret=secret_name,type=env --name=container_name image_id 

and then exec into the running container with Podman exec -it container_name bash, there is no environment variable named secret_name.

Am I missing something?

Regards

James