Add support for building and development using nix (#182)

.dockerignore

@@ -1 +1,3 @@
 .venv
+result
+*.Dockerfile

.envrc.example

@@ -0,0 +1,6 @@
+# use https://github.com/nix-community/nix-direnv  to load all tools needed to develop in the repository 
+# $ cp .envrc.example .envrc
+# $ direnv allow .
+use flake --impure . 
+
+# alternatively just use `nix develop` or `nix-shell`

.github/workflows/nix-auto.yml

@@ -0,0 +1,33 @@
+name: CI tasks from Nix config
+
+on:
+  pull_request:
+  push:
+    branches:
+      - master
+      - main
+
+jobs:
+  nix-matrix:
+    runs-on: ubuntu-latest
+    outputs:
+      matrix: ${{ steps.set-matrix.outputs.matrix }}
+    steps:
+      - uses: actions/checkout@v4
+      - uses: cachix/install-nix-action@v27
+      - id: set-matrix
+        name: Generate Nix Matrix
+        run: |
+          set -Eeu
+          matrix="$(nix eval --json '.#githubActions.matrix')"
+          echo "matrix=$matrix" >> "$GITHUB_OUTPUT"
+
+  nix:
+    needs: nix-matrix
+    runs-on: ${{ matrix.os }}
+    strategy:
+      matrix: ${{fromJSON(needs.nix-matrix.outputs.matrix)}}
+    steps:
+      - uses: actions/checkout@v4
+      - uses: cachix/install-nix-action@v27
+      - run: nix build -L '.#githubActions.checks.${{ matrix.attr }}'

.gitignore

@@ -37,3 +37,10 @@ htmlcov/
 .coverage
 .coverage.*
 .cache
+
+# Automated dev env setup - see .envrc.example
+/.envrc
+/.direnv/
+
+# nix 
+/result

README.md

@@ -17,6 +17,11 @@ See the [Development](#development) section for how to get the test agent runnin
 
 ## Installation
 
+The test agent can be installed using [nix](https://docs.determinate.systems/getting-started/):
+
+    nix profile install github:datadog/dd-apm-test-agent#ddapm-test-agent
+    # nix profile upgrade ddapm-test-agent # to upgrade
+
 The test agent can be installed from PyPI:
 
     pip install ddapm-test-agent

build-on-darwin.Dockerfile

@@ -0,0 +1,28 @@
+# simple hack to build the same image on OSX. otherwise the Nix docker build will by default not cross compile to linux
+# in CI or on linux systems - use `nix build .#image | docker load -i result` instead
+
+FROM nixos/nix AS builder
+RUN   set -xe; \
+    echo 'sandbox = true' >> /etc/nix/nix.conf; \
+    echo 'filter-syscalls = false' >> /etc/nix/nix.conf; \
+    echo 'max-jobs = auto' >> /etc/nix/nix.conf; \
+    echo 'experimental-features = nix-command flakes' >> /etc/nix/nix.conf
+
+WORKDIR /build
+COPY flake.lock *.nix .
+
+RUN nix flake show
+
+
+COPY . .
+
+RUN nix build .#image
+RUN mkdir -p /output; mkdir -p /img
+# very simplistic way to unpack image - relies only on there being a single layer
+RUN tar -xf result --strip-components=1 -C /img 
+RUN tar -xf /img/layer.tar -C /output
+
+FROM scratch AS final
+COPY --from=builder /output/ /
+
+ENTRYPOINT ["/bin/ddapm-test-agent"]

ddsketch.nix

@@ -0,0 +1,32 @@
+{ python, pkgs, ... }:
+python.pkgs.buildPythonPackage rec {
+  name = "ddsketch";
+  version = "3.0.1";
+
+  src = pkgs.fetchFromGitHub {
+    owner = "datadog";
+    repo = "sketches-py";
+    rev = "refs/tags/v${version}";
+    hash = "sha256-SmdKq5aXi5B3FNBxPQDNKNBujGGEPXF132YGadGFPpo=";
+  };
+
+  propagatedBuildInputs = with python.pkgs; [
+    six
+    protobuf
+    setuptools
+  ];
+  nativeBuildInputs = with python.pkgs; [ setuptools_scm ];
+  checkInputs = with python.pkgs; [
+    pytest
+    numpy
+  ];
+  env.SETUPTOOLS_SCM_PRETEND_VERSION = version;
+
+  pythonImportsCheck = [ "ddsketch" ];
+
+  postPatch = ''
+    patchShebangs setup.py
+    ls -lah
+    echo version=\"${version}\" > ddsketch/__version.py
+  '';
+}

ddtrace.nix

@@ -0,0 +1,72 @@
+{
+  python,
+  pkgs,
+  ddsketch,
+  ...
+}:
+
+let
+  envier = python.pkgs.buildPythonPackage rec {
+    pname = "envier";
+    version = "0.5.2";
+
+    pyproject = true;
+    propagatedBuildInputs = with python.pkgs; [
+      hatchling
+      hatch-vcs
+    ];
+
+    src = pkgs.fetchPypi {
+      inherit pname version;
+      sha256 = "sha256-Tn45jLCajdNgUI734SURoVI1VCbSVEuEh6NNrSfMIK0=";
+    };
+  };
+
+  ddtrace = python.pkgs.buildPythonPackage rec {
+    pname = "ddtrace";
+    version = "2.9.2";
+    pyproject = true;
+
+    nativeBuildInputs =
+      [ pkgs.cmake ]
+      ++ (with python.pkgs; [
+        cmake
+        setuptools
+        setuptools_scm
+        cython
+      ]);
+
+    propagatedBuildInputs = with python.pkgs; [
+      attrs
+      cattrs
+      ddsketch
+      envier
+      opentelemetry-api
+      protobuf
+      six
+      xmltodict
+      bytecode
+    ];
+
+    buildInputs = pkgs.lib.optionals pkgs.stdenv.isDarwin [ pkgs.darwin.apple_sdk.frameworks.IOKit ];
+
+    postPatch = ''
+      substituteInPlace setup.py --replace "cmake>=3.24.2,<3.28" "cmake"
+
+      # downloading artifacts is impossible in sandboxed build
+      substituteInPlace setup.py --replace "cls.download_artifacts()" "pass"
+
+      substituteInPlace pyproject.toml --replace "cmake>=3.24.2,<3.28" "cmake"
+    '';
+
+    dontUseCmakeConfigure = true;
+
+    src = pkgs.fetchFromGitHub {
+      owner = "datadog";
+      repo = "dd-trace-py";
+      rev = "refs/tags/v${version}";
+      hash = "sha256-Ax220/uBNwSZNBFYxbxAe0rmLrqYYf3a8K/PIuSE150=";
+    };
+  };
+in
+(ddtrace)