[CI] add nix check to CI

.github/workflows/nix.yml

@@ -0,0 +1,24 @@
+name: "Build nix"
+on:
+ pull_request:
+ push:
+ branches:
+ - develop
+ - compatible
+ - berkeley
+ - releases/**
+ - main
+jobs:
+ tests:
+ runs-on: ubuntu-latest
+ steps:
+ - uses: actions/checkout@v3
+ with:
+ fetch-depth: 0
+ - uses: cachix/install-nix-action@v20
+ - uses: DeterminateSystems/magic-nix-cache-action@v2
+ - run: nix/pin.sh 
+ - run: nix build mina
+ env:
+ GIT_LFS_SKIP_SMUDGE: 1
+ - run: nix develop mina

nix/modules/mina.nix

@@ -68,6 +68,7 @@ inputs:
  };
  libp2p-keypair = lib.mkOption {
  type = path;
+ default = "/root/libp2p-keys/key";
  };
 
  waitForRpc = lib.mkOption {