I'm still really puzzled why AWS lambda has golang and Azure functions has Java and python but GCF doesn't have anything but JavaScript. That's a big hole that must be leaving a lot of developers feeling frustrated.
GCF is still in beta so it's the worst case, but they recently announced Serverless Containers which will let you run anything insider a docker container on-demand. That'll get around the language barriers and is the inevitable destination of all serverless platforms eventually.
And to sign up for serverless containers: https://g.co/serverlesscontainers
(I am a PM on GCP)
https://cloudplatform.googleblog.com/2018/07/bringing-the-be...