@prologic I tried to deploy yarnd on GCP, without success, mainly because of the incompatibility with the third twelve factor principle. If I have time I will try to use viper to change it.
If I run the docker image as it, it works fine, but if I want to specify some parameters using the command line it is not really possible, because of how GCP starts the container, I must have it by env variable.
Right just found the ENV variable documentation : 
My mistake was that I was adding the following prefix :
And That is actually part of yarnc code and not yarnd code.
As soon as I have time, I will give it a new try.