Comment by tannhaeuser | Hacker News Reader

Comment by tannhaeuser | Hacker News Reader

To the Docker guys/gals around here

- I'd be more comfortable using Docker if we had alternative runtimes, Docker being just one (maybe primus-inter-pares) among them; I'm aware of runC but don't know if Docker images are realistically portable (after all, Docker with its quarterly release and only 1 year enterprise support seems relative immature still)

- I'm not 100% sure on the legal situation re: distributing Linux and GNU userland binaries along with non-F/OSS commercial software; the practice of running eg `apt-get` and fetch the base OS userland on first start (and to a lesser degree, using union'd file systems, though I like that part actually), for me, has the smell of circumventing implied GPL conditions (but IANAL)

- in that light, I'd like a characterization of Docker vs. basic built-in POSIX/Linux/FreeBSD chroot jails

- the permissions story (must start as root, effective UID in container typically not resolvable with /etc/passwd) is suboptimal

> I'm aware of runC but don't know if Docker images are realistically portable

Quay, the Docker Registry competitor from CoreOS, has automatic support for converting Docker images into rkt images (as in: you push the Docker image, and pull with rkt, and it supposedly just works). I don't know how well it works in practice, though I can't imagine (from the top of my head) why it shouldn't. A Docker image is mostly a layered tarball with a few fields of metadata. Nothing particularly obscure.

Docker is trying to alleviate this concern by spinning out and trying to foster alternative runtimes, check out containerd and runc:

* https://blog.docker.com/2016/12/introducing-containerd/ * https://runc.io/

> I'm aware of runC but don't know if Docker images are realistically portabl

(It wasn't clear from your comment if you were aware of this) Since last year (docker 1.11) docker itself no longer is a runtime, and uses runC as the default runtime (https://blog.docker.com/2016/04/docker-engine-1-11-runc/)

Additional OCI compliant runtimes can be configured on the daemon (https://docs.docker.com/engine/reference/commandline/dockerd...), and can be selected per container, using the "--runtime" option on "docker run" (https://docs.docker.com/engine/reference/commandline/run/#op...)

> I'm aware of runC but don't know if Docker images are realistically portable

Until recently Cloud Foundry ran Docker images with a custom runtime backend (garden-linux). It's since switched to using runC (garden-runc). So in principle it was always possible to do this.

A major reason for the switch was to reduce duplicated effort.

Disclosure: I work for Pivotal, a major contributor to Cloud Foundry. Insofar as Docker move towards the value line, we're competitors.

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