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Cheap Docker images with Nix

lethalman.blogspot.com

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Re: Cheap Docker images with Nix

#11

Post by Artemis2 »

TomFrost wrote: post #9

If the goal is solely Docker images with a standard size in the 20-40MB range, this can be achieved without additional tooling. After switching our development and deployment flow to docker, my team quickly tired of the 200-400MB images that seemed to be accepted as commonplace. We started basing our containers on alpine (essentially, busybox with a package manager) or alpine derivatives, and dropped into that target…

Same here! Switching to Alpine for most services was essentially painless. To go a step further, the images with binaries that have no dependencies (mostly programs written in Go) use scratch Docker images. This way we get 5MB images, where the size overhead of Docker is nothing.

Re: Cheap Docker images with Nix

#12

Post by trishume »

josh-wrale wrote: post #10

@Lethalman: Can you expound on this? > Be aware that things like PAM configurations, or other stuff, created to be suitable for Debian may not work with Nix programs that use a different glibc. So this would not be a factor using the method which has no base? The Debian base approach seems like a non-starter if negative emergent behavior like PAM config mismatches are common. Also, to be sure, I can do this "no base…

Yes, AFAIK you can build docker containers with Nix on any Linux machine with the nix package manager installed. You can even build them on OSX if you configure your OSX Nix install with a remote build machine that runs Linux (yes, Nix can automatically and transparently distribute your builds).

Re: Cheap Docker images with Nix

#13

Post by Lethalman »

nickjj wrote: post #8

Why isn't he using the Alpine based Redis image when comparing final image sizes? It's unfair to say the official Redis image is 177mb because the Alpine version is available on the Docker Hub[1] and it's only 15.95mb. Alpine is pretty awesome if your main goal is to shrink images without any effort[2]. [1] https://hub.docker.com/_/redis/ [2] http://nickjanetakis.com/blog/alpine-based-docker-images-mak...

You are right. It's unfair, I'm going to modify the post to mention alpine.

The post is both about tiny images AND how to build docker images with nix. I think it was an interesting tooling to make for our community. Some Nix people are already using it for obvious reasons.

Re: Cheap Docker images with Nix

#14

Post by _0w8t »

A common problem with Docker is after running a compiler/preprocessor during an image build one ends up with the bulid tools inside the image. A workaround is to use a shell script that first gets the image with the compiler, run it and then pass the output to the Docker build. But this is non-standard and encourages running random scripts on the build host defeating the advantages of using Docker during development to isolate build system. It is nice that Nix addresses this.

Re: Cheap Docker images with Nix

#15

Post by _0w8t »

Artemis2 wrote: post #11
TomFrost wrote: post #9

If the goal is solely Docker images with a standard size in the 20-40MB range, this can be achieved without additional tooling. After switching our development and deployment flow to docker, my team quickly tired of the 200-400MB images that seemed to be accepted as commonplace. We started basing our containers on alpine (essentially, busybox with a package manager) or alpine derivatives, and dropped into that target…

Same here! Switching to Alpine for most services was essentially painless. To go a step further, the images with binaries that have no dependencies (mostly programs written in Go) use scratch Docker images. This way we get 5MB images, where the size overhead of Docker is nothing.

I have found that images with a single executable and perhaps /etc/passwd with no other files prevents to use docker exec as a valuable debugging/poking tool. My preference is to have a single image with all the services and basic tools included and use it to run all the containers on the machine.

Re: Cheap Docker images with Nix

#16

Post by speedkills »

Installed emacs with nix last weekend to use with spacemacs. Three errors at startup that didn't make sense but I had a feeling that nix was the problem so rolled back and reinstalled with brew. Worked perfectly. Nix has some great ideas but when the install of emacs took 10 times as long as homebrew, then didn't work correctly it didn't leave me wanting to use it for anything work related like my docker images.

Hopefully with time, their planned cli improvements and binary caching it will be a contender but that feels a ways off at this point.

Re: Cheap Docker images with Nix

#17

Post by fishnchips »

I'm wondering what would be the advantage of using Nix versus building on Alpine Linux with good understanding how Docker layers work. My main reason to be skeptical about Nix is the need to learn a new single-purpose language as opposed to just using Shell like you do in Dockerfiles.

Re: Cheap Docker images with Nix

#18

Post by xienze »

_0w8t wrote: post #14

A common problem with Docker is after running a compiler/preprocessor during an image build one ends up with the bulid tools inside the image. A workaround is to use a shell script that first gets the image with the compiler, run it and then pass the output to the Docker build. But this is non-standard and encourages running random scripts on the build host defeating the advantages of using Docker during development…

Or you could remove the tools at the end of your Dockerfile...

Edit: am I missing something? This is a legitimate solution to the problem. Install the tools, compile, and remove them. The parent is suggesting a very clumsy approach (build on the host and pass the binary to the container as it's being built).

Re: Cheap Docker images with Nix

#19

Post by ocharles »

speedkills wrote: post #16

Installed emacs with nix last weekend to use with spacemacs. Three errors at startup that didn't make sense but I had a feeling that nix was the problem so rolled back and reinstalled with brew. Worked perfectly. Nix has some great ideas but when the install of emacs took 10 times as long as homebrew, then didn't work correctly it didn't leave me wanting to use it for anything work related like my docker images. Hope…

If there are any bug reports you could file, that would be much appreciated. Installing Emacs should just be a case of downloading the prebuild binaries, which shouldn't take long at all. I use Spacemacs and have never encountered any problems. I have a feeling things are still a lot worse on OSX though...

Re: Cheap Docker images with Nix

#20

Post by davexunit »

fishnchips wrote: post #17

I'm wondering what would be the advantage of using Nix versus building on Alpine Linux with good understanding how Docker layers work. My main reason to be skeptical about Nix is the need to learn a new single-purpose language as opposed to just using Shell like you do in Dockerfiles.

Both the Nix language and the Dockerfile language include embedding shell scripts. Let's not pretend that Docker doesn't have its own DSL to learn. Dockerfile's are imperative, where as Nix is declarative and functional, which is a big improvement.
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