IsolateKit is a lightweight Docker/rkt/containerization alternative, designed specifically for creating reproducible development environment, vs Docker and rkt's general-purpose usage.
Docker is great, but it wasn't designed for containers. For instance:
- The only way to use multiple images at once is through multi-stage builds, which, though great, make it difficult to install multiple dependencies. Have a project that needs to be built on CentOS and depends on devtoolset-7, Python, and Ruby in one build stage? Tough luck; you'll have to pick one image and then install everything else onto it manually.
- It's a bit unintuitive to run an image directly using a temporary container. Want to
run the Alpine image just once? Try
docker run -t -i --rm alpine ash. Ouch. - The new mount syntax makes bind mounts (which is what you'll almost always be using
for building binaries) painful:
--mount type=bind,source=xyz,destination=xyz. - You can only depend on already-built images, not unbuilt Dockerfiles. This makes creating multiple images harder than it needs to be.
- acbuild combines everything wrong with state machines and everything wrong with declarative build formats into one.
- AppC is dead, and rkt doesn't support OCI yet. Oh, as as a result of OCI, acbuild is unmaintained.
Rootbox, IsolateKit's predecessor, was great, but it had a lot of problems:
- I wrote it in Bash. Seemed like a good idea at the time, ended up being an epic disaster.
- There was no concept of proper dependency management, so creating new boxes required running all of the factories it depended on...even if there was no need.
- It was hard-coded to Alpine Linux and wasn't designed in a way to make it easily extensible. Alpine is great for building static binaries, but you can't use it to build other things like AppImages.
- Lightweight. GLib is the only runtime dependency, and Vala is the only built-time dependency.
- Built on top of systemd-nspawn.
- Designed to make generating environments from source scripts insanely easy. IsolateKit in its current state isn't really designed around using binary images.
# Create a new target that depends on the Alpine unit.
$ ik target set test -a ik:alpine.rc
# Run the new target.
$ ik target run test
# Run the new target, but also add the SDK unit.
$ ik target run test -a ik:alpine/sdk.rc
# Run the Alpine unit, but with no target.
# This will discard any changes made (think docker run --rm).
$ ik target run null -a ik:alpine.rc,alpine/sdk.rc