Setup nix flake

.gitignore

@@ -1 +1,4 @@
+.DS_Store
 /target
+/output
+result

CONTRIBUTING.md

@@ -0,0 +1,49 @@
+# Building the Dockerfile without having nix installed (inside docker)
+
+1. Starting the Docker container
+
+```
+docker run -it --rm -v "$(pwd):/app" nixos/nix
+```
+
+2. Enable flakes
+
+```
+echo 'experimental-features = nix-command flakes' >> /etc/nix/nix.conf
+```
+
+3. Switch to app directory
+
+```
+cd /app
+```
+
+4. Build the binary
+
+```
+nix build .#bin
+```
+
+5. Copy the binary to the output folder
+
+```
+cp -r $(readlink -f result) output
+```
+
+6. Build the Docker image
+
+```
+nix build .#dockerImage
+```
+
+7. Copy the Docker image to the output folder
+
+```
+cp $(readlink -f result) output/docker-image.tar.gz
+```
+
+# Importing the nix-built image into docker
+
+```
+docker load -i output/docker-image.tar.gz
+```

examples/minimal/docker-compose.yml

@@ -4,8 +4,7 @@ services:
   principal:
     container_name: principal
     command: --port 8080 --threshold 10 --rate 10s --timeout 60s --container http-echo --debug
-    build:
-      context: ../../
+    image: principal:latest
     ports:
       - 8080:8080
     volumes:

flake.nix

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+{
+  inputs = {
+    nixpkgs.url = "github:NixOS/nixpkgs/nixpkgs-unstable";
+    flake-utils.url = "github:numtide/flake-utils";
+
+    rust-overlay = {
+      url = "github:oxalica/rust-overlay";
+      inputs = {
+        nixpkgs.follows = "nixpkgs";
+        flake-utils.follows = "flake-utils";
+      };
+    };
+
+    crane = {
+      url = "github:ipetkov/crane";
+      inputs = { nixpkgs.follows = "nixpkgs"; };
+    };
+  };
+  outputs = { self, nixpkgs, flake-utils, rust-overlay, crane }:
+    flake-utils.lib.eachDefaultSystem (system:
+      let
+        overlays = [ (import rust-overlay) ];
+        pkgs = import nixpkgs { inherit system overlays; };
+        rustToolchain = pkgs.pkgsBuildHost.rust-bin.fromRustupToolchainFile
+          ./rust-toolchain.toml;
+        craneLib = (crane.mkLib pkgs).overrideToolchain rustToolchain;
+        src = craneLib.cleanCargoSource ./.;
+        nativeBuildInputs = with pkgs; [ rustToolchain pkg-config ];
+        buildInputs = with pkgs; [ openssl libpcap ];
+        commonArgs = { inherit src buildInputs nativeBuildInputs; };
+        cargoArtifacts = craneLib.buildDepsOnly commonArgs;
+
+        bin = craneLib.buildPackage (commonArgs // {
+          inherit cargoArtifacts;
+
+          # Compile but don't run the tests 
+          cargoTestExtraArgs = "--no-run";
+        });
+
+        dockerImage = pkgs.dockerTools.buildImage {
+          name = "principal";
+          tag = "latest";
+          copyToRoot = [ bin ];
+          config = { Entrypoint = [ "${bin}/bin/principal" ]; };
+        };
+      in
+      with pkgs; {
+        packages = {
+          inherit bin dockerImage;
+          default = bin;
+        };
+        devShells.default = mkShell { inputsFrom = [ bin ]; };
+      });
+}

rust-toolchain.toml

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+[toolchain]
+channel = "stable"
+components = ["rustfmt", "rustc-dev", "clippy"]