Drone 0.8: Using secrets in steps not supporting reading from env vars

[bradrydzewski]

@jakubka

However, we still have situations where our plugin attributes can be arbitrary Dict like this:

I describe a pattern for handling this use case here:
http://discuss.harness.io/t/how-can-i-pass-secrets-as-build-args-to-plugins-docker-drone-0-8/824/2

Note that we use this pattern with the docker plugin, where we need to provide the plugin with an arbitrary dictionary of parameters for build-args, which in some cases may need to be sourced from secrets or the environment.

So you might instead do something like this:

some-deploy-step:
  image: custom-deploy-plugin
  custom_params:
    param1: something
    param2: something
-   param3: $$PASSWORD_STORED_AS_DRONE_SECRET
+ custom_params_from_env: [ PASSWORD_STORED_AS_DRONE_SECRET ]

or this

some-deploy-step:
  image: custom-deploy-plugin
  custom_params:
    param1: something
    param2: something
-   param3: $$PASSWORD_STORED_AS_DRONE_SECRET
+ custom_params_from_env: 
      param3: PASSWORD_STORED_AS_DRONE_SECRET