evaluate "Docker for Mac" as a Dinghy replacement

[codekitchen]

You have to agree to an NDA to get into the private beta, but I've gleaned plenty of information from public sources:

https://blog.docker.com/2016/03/docker-for-mac-windows-beta/
https://news.ycombinator.com/item?id=11352594

I've been saying for 18 months that Docker should solve the OS X dev problem themselves, so I'm a big fan of this. From what I've read so far it seems pretty close to Dinghy in terms of features.

• Mounted volumes are shared from the host using an as-yet-unknown solution that appears to support fsevents. Hopefully its performance is at least close to NFS, if not better.
• Claims that it remaps MacOS X UIDs into Linux ones (no more permissions problems), which could mean a couple different things. Hopefully it is aimed at editing code on a mounted volume.
• DNS resolving, apparently with routing the docker network interfaces directly to the host rather than through any proxy. I'd considered doing this too but never got around to it, it's a nice improvement over Dinghy's current solution. The HTTP proxy would still be nice for making SSL termination easy but that could be layered on top.
  • Not sure how DNS names will be chosen. I've come to really like the docker-compose based names but even if it's just <containername>.docker.local that'd be ok.
• Uses xhyve, which is about 10% slower than virtualbox for typical dev tasks in my testing. However, I've already switched to the dinghy xhyve driver myself because it's so much more pleasant than virtualbox for this use case.

Overall it sounds really nice. The proof will be once we can actually try it out, but if it works as well as they claim I'll probably just deprecate Dinghy once Docker for Mac is publicly released. That's assuming Docker for Mac is a free product, I'd hope it would be but they haven't said, and it sounds like at least parts of it will not be open source.

[codekitchen]

Looks like that's already been clarified, Docker for Mac will be free and open source.

https://news.ycombinator.com/item?id=11353747

[ryansch]

Agreed. This looks to be very exciting. I'm waiting for my invite :-)

[rkazak]

Me too!

[mrmachine]

I've been testing the beta today. The way it maps permissions for mounted volumes is different, and a little weird. It seems to map all bind mounted volumes to whatever UID:GID you are currently running as inside the container. So when you gosu foo, the owner and group of all your bind mounted volumes will change from root to foo.

In theory, this sounds like it should resolve the existing issue where you have to create/modify a user inside the container to match the UID:GID of the bind mounted volumes (which can't be changed). But I was previously working around that by doing gosu "$(stat -c '%u' "${DIR}"):$(stat -c '%g' "${DIR}")" which no longer works as expected.

So at the very least, this different behaviour has broken parity with images that work under regular Docker Engine.

Here's what their docs say. Sounds like this feature might be short-lived:

Presently, all requesting processes are treated as owners and group members on all bind mounted file system resources. This behavior simultaneously solves uid/gid mapping headaches and creates new compatibility (and possibly security) issues. A finer-grained ownership model is in development.

[codekitchen]

I tested out the beta for a bit yesterday, but ran into I/O errors when trying to bundle install onto a host-mounted volume. I haven't had a chance to dig further yet. Interestingly they're almost exactly the same git clone I/O errors I got when trying to run the unfsd NFS daemon as a non-root user. git seems to be especially sensitive to filesystem bugs.

[uberjay]

Unfortunately the Docker for Mac beta is significantly slower than dinghy for my workflow. I use the vmware driver -- between the osxfs driver burning significant CPU and the overhead of xhyve, a build which normally takes a little over 4 minutes ends up taking over 20 minutes.

I currently use vagrant for most of my development environment management, but jumped on the docker for mac beta in hopes it would simplify my workflow. And it does! However, the performance is bad enough that it's unusable for me. I have no doubt that xhyve performance will improve over time... eventually, it may be a good alternative. Dinghy to the rescue! :)

[codekitchen]

Yeah, I believe them when they say the FS performance will improve over time, they should be able to beat NFS performance using their architecture, with some work.

[michaellopez]

I've been playing with Docker for Mac the past few days. What I'm missing is the DNS functionality that Dinghy provides. I'm hoping that they include a custom DNS but looking at this thread it doesn't look like it...anytime soon anyways. Is there anyway to break out the DNS part of Dinghy into its own component that can be reused by Dinghy and standalone by Docker for Mac users?

[codekitchen]

Yep, the HTTP proxy and DNS server have been split into a separate project, install instructions are at https://github.com/codekitchen/dinghy-http-proxy#os-x

[michaellopez]

@codekitchen That's great. Thank you. I will give it a spin....I still find Docker for Mac unstable so I'll stick to Dinghy for the time being. 🍰

[cweagans]

osxfs still can't compete with nfs or even the vbox guest additions. It's so slow. IMO, Docker for Mac is not a complete replacement yet.

[igorvpcleao]

Hey @codekitchen,
Sorry for a silly question. Is it possible to run dinghy with docker-beta?

Thx!

[michaellopez]

@igorvpcleao From what I understand, the only thing you'd want from Dinghy would be its proxy & DNS which are available here https://github.com/codekitchen/dinghy-http-proxy. One major aspect of Docker for mac is to make osxfs performant and stable. So the NFS and fsevents from Dinghy should not really be needed in Docker for mac.

So if/once https://forums.docker.com/t/custom-dns-for-resolving-containers/8361 gets fixed/merged then I think that Dinghy might be up for deprecation all together.

But until Docker for mac is stable (which it wasn't when I tried it last month) I'm sticking to Dinghy. Now I just received e-mail from Docker that Docker for mac/windows is RC. Might be worth testing it out again.