Introduce Nix development flake

[aaronmondal]

Provide a mostly self-contained development environment automatically sets up tooling like Cargo and Bazel via nix.

This makes it easy for nix users to contribute to our project and enables future work on reproducible release binaries and containers.

---

This change is 

[aaronmondal]

cc @blakehatch I can't add you as reviewer for some reason

[allada]

Reviewed 10 of 10 files at r1.
Reviewable status: 8 of 10 files reviewed, 4 unresolved discussions (waiting on @aaronmondal and @MarcusSorealheis)

---

flake.nix line 10 at r1 (raw file):

  outputs = inputs@{ nixpkgs, flake-parts, ... }:
    flake-parts.lib.mkFlake { inherit inputs; } {
      systems = [ "x86_64-linux" ];

What about mac, windows, ARM?

---

.github/workflows/nix.yaml line 14 at r1 (raw file):

jobs:
  nix-bazel:
    runs-on: ubuntu-latest

nit: Lets pin specific versions.

---

.github/workflows/nix.yaml line 39 at r1 (raw file):

          bash -c "bazel test ..."
  nix-cargo:
    runs-on: ubuntu-latest

nit: ditto.

---

tools/wrapped-bazel.nix line 18 at r1 (raw file):

]]; then
    ${bazel}/bin/bazel $1 \
        --action_env=OPENSSL_INCLUDE_DIR="${openssl.dev}/include" \

nit: just put this into the .bazelrc something like:

build:nix --action_env=OPENSSL_INCLUDE_DIR
build:nix --action_env=OPENSSL_LIB_DIR

Then just inject those enviorns to bazel.

Then run bazel as "$@" --config nix

[aaronmondal]

flake.nix line 10 at r1 (raw file):

Previously, allada (Nathan (Blaise) Bruer) wrote…

What about mac, windows, ARM?

Native Windows doesn't work with Nix. WSL2 usually defaults to Ubuntu. As long as we don't depend on CUDA the current workflows should cover that.

I can't test Mac at the moment. I propose to postpone this until we have a way to debug those builds on Mac x86_64 and ARM.

[allada]

Reviewed 1 of 1 files at r3, all commit messages.
Reviewable status: 8 of 10 files reviewed, 1 unresolved discussion (waiting on @aaronmondal and @MarcusSorealheis)

---

flake.nix line 10 at r1 (raw file):

Previously, aaronmondal (Aaron Siddhartha Mondal) wrote…

Native Windows doesn't work with Nix. WSL2 usually defaults to Ubuntu. As long as we don't depend on CUDA the current workflows should cover that.

I can't test Mac at the moment. I propose to postpone this until we have a way to debug those builds on Mac x86_64 and ARM.

Yeah sounds good :-)

[aaronmondal]

tools/wrapped-bazel.nix line 18 at r1 (raw file):

Previously, allada (Nathan (Blaise) Bruer) wrote…

nit: just put this into the .bazelrc something like:

build:nix --action_env=OPENSSL_INCLUDE_DIR
build:nix --action_env=OPENSSL_LIB_DIR

Then just inject those enviorns to bazel.

Then run bazel as "$@" --config nix

That doesn't work in this case because these paths are dynamically generated and the .bazelrc can't resolve $SOMEVARIABLE. We'd have to manually update these environment variables every time someone updates the flake. I had something like that at some point but it was too tedious to keep it in sync.

[allada]

Reviewable status: 8 of 10 files reviewed, all discussions resolved

---

tools/wrapped-bazel.nix line 18 at r1 (raw file):

Previously, aaronmondal (Aaron Siddhartha Mondal) wrote…

That doesn't work in this case because these paths are dynamically generated and the .bazelrc can't resolve $SOMEVARIABLE. We'd have to manually update these environment variables every time someone updates the flake. I had something like that at some point but it was too tedious to keep it in sync.

On the line above this, cant you just use:
export OPENSSL_INCLUDE_DIR="${openssl.dev}/include"

The --action_env will auto-pickup those environs.

?