This isn't a problem specific to Docker though. If you want to transform any HTTP API composably, you want something like this, and my head is swimming with all of the awesome things you could do with a general proxy that easily allows this.
I also agree that it's a problem rearing its head in the Docker community, but that seems incidental to the problem itself. This is ostensibly fixing a Docker problem, but it could do much more for us all if it didn't artificially constrain itself to that domain. That's all I'm saying.
So it's basically an easily pluggable transforming HTTP proxy. That's pretty cool.
My question is, what does this have to do with Docker at all? I understand the use case, and I agree it's useful for Docker extensions. But this looks like it has no reason to limit itself to one application; this functionality is useful for a lot of usecases beyond Docker's API, and it could even benefit its design to be a generalist HTTP transform.
Also, this gives me echoes of xkcd [1]. Is the right way to solve the too many standards problem by wrapping it in one more standard?
I also agree that it's a problem rearing its head in the Docker community, but that seems incidental to the problem itself. This is ostensibly fixing a Docker problem, but it could do much more for us all if it didn't artificially constrain itself to that domain. That's all I'm saying.
Still, neat.