set context param value from env variable

[#1]

 I am working with context params now since most all sources are saying they are a better choice than variables.  However I'm not finding how I can set the context param values from anywhere other than the UI?  I need to be able to pass env values from my docker-compose file and ultimately have them end up as the value of a context param.  (This worked for variables.)  Context params don't seem to support EL so I can't pull outside values into the context param that way.  Any ideas? 

[#2]

 I'm still working around this one using the variable registry.

My use case seems fairly common- our docker compose file uses the environment stanza to pass environment-specific values into the NiFi container for use by various processors.  e.g. things like S3 key/secret.  I need to inject this information into the value of my context params.  Or, find some other way to easily set the value of the context params from my docker-compose.  I believe the NiFi toolkit can update the value of the context params but to fully automate this would require additional moving parts.

Anyone have a suggestion on how to accomplish this?