Fallback to alternative env variable

[paichinger]

Let's say we have the following:

- name: my-service
  namespace: {{ env "MY_SERVICE_NAMESPACE" | default "default" }}

Now, I'd like to check on another env variable for the namespace before the default fallback is used. Something like:

- name: my-service
  namespace: {{ env "MY_SERVICE_NAMESPACE" <OR ELSE> env "DEFAULT_NAMESPACE"  | default "default" }}

Unfortunately I couldn't figure out how to do this <OR ELSE> in an elegant (not too verbose) way.
This is working, but I was wondering if there's a better way to do this, it feels very cluttered:

{{ $MY_SERVICE_NAMESPACE := "" }}
{{ if env "MY_SERVICE_NAMESPACE" }}
  {{ $myServiceNamespace = env "MY_SERVICE_NAMESPACE" }} 
{{ else }}
  {{ $myServiceNamespace = env "DEFAULT_NAMESPACE"  }}
{{ end }}
- name: my-service
  namespace: {{ $myServiceNamespace  | default "default" }}

Any hints are appreciated!

[andrewnazarov]

Maybe coalesce will help

Probably something like this:

namespace: {{ printf "%s" (coalesce (env "MY_SERVICE_NAMESPACE") (env "DEFAULT_NAMESPACE") "default") }}

[paichinger]

coalesce did the trick. I think printf "%s" is not even needed. For me this is working:
namespace: {{ coalesce (env "MY_SERVICE_NAMESPACE") (env "DEFAULT_NAMESPACE") "default") }}
Much nicer than what I had, thanks you very much!