<!-- The PR description should answer 2 important questions: -->
### What
Add `coreutils` to Docker images.
### How
<!-- How is it trying to accomplish it (what are the implementation
steps)? -->
V3_GIT_ORIGIN_REV_ID: a614c47758b726729208428890586d5aabac0797
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### What
<!-- What is this PR trying to accomplish (and why, if it's not
obvious)? -->
<!-- Consider: do we need to add a changelog entry? -->
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### How
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steps)? -->
V3_GIT_ORIGIN_REV_ID: c09d42519cdd4946527e72a8066d7aa60a75a4cf
### What
Use powerful constructs such as loops to avoid duplication in
`flake.nix`.
We are able to iterate over the list of binaries and list of target
systems and produce a list of packages from there.
### How
We generate a `targets` tree (see the `flake.nix` file comments for
details), and then generate the list of packages from there.
When using `nix run`, you'll get a package, which is usually what you
want.
The scripts that build Docker images run `nix build
'.#targets.x86_64-linux.<binary>.<arch>.docker`, which is verbose but
explicit.
V3_GIT_ORIGIN_REV_ID: 2a13fb31a41829f9804dfdb7c1a51a9e54e0922e
<!-- The PR description should answer 2 (maybe 3) important questions:
-->
### What
Allow engine to connect to NDCs via HTTPS.
<!-- What is this PR trying to accomplish (and why, if it's not
obvious)? -->
<!-- Consider: do we need to add a changelog entry? -->
### How
Add `cacert` to Docker image using Nix.
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steps)? -->
V3_GIT_ORIGIN_REV_ID: 52458920236f3868cc8daf18e140f8536d9bc674
<!-- Thank you for submitting this PR! :) -->
## Description
In order to test things quicker, we'd like to be able to build custom
connector and friends in Nix, and then use the containers when running
tests. First step here is to be able to build Docker containers in Nix,
and add a CI job to ensure it still works.
Then we'll move onto publishing and using these images.
No-op build times:
<img width="336" alt="Screenshot 2024-04-25 at 15 53 56"
src="https://github.com/hasura/v3-engine/assets/4729125/47cbc0c5-6e54-4583-aa01-0528d4a21080">
Functional no-op.
V3_GIT_ORIGIN_REV_ID: 8f9d609e26cdd3b0801e61fd361c241ad504dcdf
