Variable interpolation when running 'rancher catalog install' from the CLI

I want to check that my assumption that variable interpolation is not available when running rancher catalog install from the CLI is correct.

When I issue the command:

gp_finder_docker_image_tag=PR999 rancher catalog install --name test "NHSuk_Staging/c2s-gp-finder"

I am still prompted for the gp_finder_docker_image_tag value which suggests to me that interpolation is not happening. The catalog repo I’m using is https://github.com/nhsuk/nhsuk-rancher-templates/tree/master/templates/c2s-gp-finder.

If interpolation should work then any clues as to what I’m doing wrong would be appreciated.

Cheers

Neil

Rancher: 1.5.1
Rancher CLI: 0.5.0
Docker: 17.03.0-ce, build 60ccb22