rules_docker VS rules_foreign_cc

My company uses Bazel's rules docker to build our images: https://github.com/bazelbuild/rules_docker

They're pretty great and have a lot of the caching and parallelism benefits mentioned in the post for free out of the box, along with determinism (which Docker files don't have because you can run arbitrary shell commands). Our backend stack is also built with Bazel so we get a nice tight integration to build our images that is pretty straightforward.

We've also built some nice tooling around this to automatically put our maven dependencies into different layers using Bazel query and buildozer. Since maven deps don't change often we get a lot of nice caching advantages.

I've seen rules_docker is looking for maintainers here ; Does this mean it doesn't use it that much internally? If so, how do they go about using other services e.g docker-compose for running external services e.g database?

Did you mean this one? https://github.com/bazelbuild/rules_docker

I was very interested in this Bazel-based way of building containers but its README page says "it is on minimal life support," which does not inspire confidence. How's your experience using it?

As others have said docker in docker or a separate build server are your best options using docker. You can also use Bazel (which doesn't require the docker daemon) to build docker images which will build deterministic images every time due to not incorporating the timestamp: https://github.com/bazelbuild/rules_docker

There's some BazelCon talks about people doing similar stuff but not actually open sourcing their code.

P.S. if you use rules_docker please feel free to open a PR to add your company to our README: https://github.com/bazelbuild/rules_docker/#adopters

The docker utility isn't the only way to build and run containers. There's also cri-o, podman, and crun among others for running containers. For building there is podman again, Jib for Java applications, and bazel plus many others. The docker approach of using a client to connect to a daemon required to run as root has turned out to be slow and insecure.

During the last 3 years I've had the pleasure of using Bazel's rules_docker to generate all my container images (https://github.com/bazelbuild/rules_docker).

In a nutshell, rules_docker is a set of build rules for the Bazel build system (https://bazel.build). What's pretty nice about these rules is that they don't rely on a Docker daemon. They are rules that directly construct image tarballs that you can either load into your local Docker daemon or push to a registry.

What's nice about this approach is that image generation works on any operating system. For example, even on a Mac or Windows system that doesn't have Docker installed, you're able to build Linux containers. They are also fully reproducible, meaning that you often don't need to upload layers when pushing (either because they haven't changed, or because some colleague/CI job already pushed those layers).

I guess rules_docker works fine for a variety of programming languages. I've mainly used it with Go, though.

Hello, readline or ncurses can be built using bazel rules foreign cc. Just in case…

To actually answer your question, I searched for "TemplateVariableInfo" in the rules_foreign_cc project (since TemplateVariableInfo is the provider that declares template variables), and there's only one location: toolchains/toolchains.bzl. Reading this, the `toolchains.data.env` variable that's set is coming after a call to `expand_locations_and_make_variables` (from foreign_cc/private/framework.bzl), so without running a debugger I have no idea what's there. It's possible that the rules themselves are confused about this.