.dockerignore

@@ -1,12 +1,8 @@
 .git
 .gitignore
-tests
 result
 result-*
 __pycache__
 *.pyc
 .pytest_cache
-flake.nix
-flake.lock
-package.nix
 compose.yaml

.gitea/workflows/build-and-publish.yaml

@@ -43,20 +43,11 @@ jobs:
           # from the conventional-commit messages since the last release.
           fetch-depth: 0
 
-      - name: Set up Python
-        uses: actions/setup-python@v5
-        with:
-          python-version: 3.13
-
-      # The test suite runs real encodes, so ffmpeg is a test dependency.
-      - name: Install ffmpeg
-        run: sudo apt-get update && sudo apt-get install --no-install-recommends -y ffmpeg
-
-      - name: Install test dependencies
-        run: python -m pip install --upgrade pip && pip install pytest
-
-      - name: Run unit tests
-        run: python -m pytest
+      # The suite runs inside the image, against the ffmpeg that ships, rather
+      # than against whatever the runner happens to provide. A failing test
+      # fails the build. Layers are shared with the push build below.
+      - name: Run the test suite inside the image
+        run: docker build --target test -t music-mirror:test .
 
       - name: Determine registry host
         run: echo "REGISTRY=${GITHUB_SERVER_URL#*://}" >> "$GITHUB_ENV"
@@ -145,6 +136,9 @@ jobs:
         uses: docker/build-push-action@f9f3042f7e2789586610d6e8b85c8f03e5195baf # v7
         with:
           context: .
+          # Without this the last stage in the Dockerfile -- the test stage --
+          # would be what gets published.
+          target: runtime
           # amd64 for the NAS, arm64 so the same image runs on a Pi.
           platforms: linux/amd64,linux/arm64
           push: ${{ github.event_name != 'pull_request' }}
@@ -165,7 +159,7 @@ jobs:
         run: |
           set -euo pipefail
 
-          python - "$VERSION" <<'PY'
+          python3 - "$VERSION" <<'PY'
           import pathlib
           import re
           import sys

Dockerfile

@@ -1,4 +1,4 @@
-FROM python:3.13-slim
+FROM python:3.13-slim AS runtime
 
 ENV PYTHONUNBUFFERED=1
 
@@ -10,8 +10,19 @@ RUN apt-get update \
 WORKDIR /app
 COPY pyproject.toml README.md ./
 COPY music_mirror.py ./
-RUN pip install --no-cache-dir .
+RUN pip install --no-cache-dir . \
+    && rm -rf build music_mirror.egg-info
 
 # Runs as root by default so a bind-mounted dataset of any ownership is
 # writable. Override with `user:` in compose to run as the dataset's owner.
 ENTRYPOINT ["music-mirror"]
+
+# Test stage: the suite runs against this image's own ffmpeg, which is the one
+# that ships. Build it with `--target test`; a failing test fails the build.
+# The published image is the `runtime` stage above and carries none of this.
+FROM runtime AS test
+
+RUN pip install --no-cache-dir pytest
+COPY pytest.ini ./
+COPY tests ./tests
+RUN python -m pytest

README.md

@@ -78,8 +78,7 @@ music-mirror --source /music --mirror /music-mp3 --subdir "Artist/Album"
 `--subdir` never prunes: a partial pass cannot tell an orphan from a file
 outside its own scope.
 
-Requires `ffmpeg` and `ffprobe` on `PATH`. The container and the Nix package
-both provide them.
+Requires `ffmpeg` and `ffprobe` on `PATH`. The container image provides both.
 
 ## Running it on TrueNAS Scale
 
@@ -103,25 +102,26 @@ New Lidarr imports are picked up on the next pass. With `MUSIC_MIRROR_INTERVAL`
 at `6h` that is the worst case; run `--subdir` by hand if you want an album
 immediately.
 
-## Nix
-
-```sh
-nix run .#music-mirror -- --source ./flac --mirror ./mp3
-nix build .#music-mirror   # the test suite runs as part of the build
-nix develop                # python, pytest and ffmpeg
-```
-
-`overlays.default` provides `pkgs.music-mirror`.
-
 ## Tests
 
 ```sh
-pytest
+docker build --target test .   # what CI runs
+pytest                         # needs ffmpeg and pytest on PATH
 ```
 
-The tests run real ffmpeg encodes rather than mocking them — the interesting
+The suite runs real ffmpeg encodes rather than mocking them. The interesting
 failures are in what ffmpeg actually does with tags, cover art and container
-formats, and a mock cannot fail that way. They skip if ffmpeg is absent.
+formats, and a mock cannot fail that way — which is also why CI runs the tests
+_inside the image_, against the ffmpeg that ships, rather than against whatever
+the build runner provides. The published image is the `runtime` stage and
+carries neither the tests nor pytest.
+
+Run them directly instead if you prefer; they skip when ffmpeg is absent. On a
+Nix machine:
+
+```sh
+nix shell nixpkgs#python3Packages.pytest nixpkgs#ffmpeg -c pytest
+```
 
 ## Getting the result onto an iPod
 

flake.lock

@@ -1,27 +0,0 @@
-{
-  "nodes": {
-    "nixpkgs": {
-      "locked": {
-        "lastModified": 1787135253,
-        "narHash": "sha256-RD2kNWCG+Bjo6h+JVjWVNntZs2GtRoeY2xHjts/FNkA=",
-        "owner": "nixos",
-        "repo": "nixpkgs",
-        "rev": "ffb3c9b700e759be2ef13237c9d8f953b32a1e46",
-        "type": "github"
-      },
-      "original": {
-        "owner": "nixos",
-        "ref": "nixos-unstable",
-        "repo": "nixpkgs",
-        "type": "github"
-      }
-    },
-    "root": {
-      "inputs": {
-        "nixpkgs": "nixpkgs"
-      }
-    }
-  },
-  "root": "root",
-  "version": 7
-}

flake.nix

@@ -1,42 +0,0 @@
-{
-  description = "Maintain a lossy MP3 mirror of a lossless music library";
-
-  inputs.nixpkgs.url = "github:nixos/nixpkgs/nixos-unstable";
-
-  outputs =
-    { self, nixpkgs }:
-    let
-      systems = [
-        "x86_64-linux"
-        "aarch64-linux"
-        "x86_64-darwin"
-        "aarch64-darwin"
-      ];
-      forAllSystems = fn: nixpkgs.lib.genAttrs systems (system: fn nixpkgs.legacyPackages.${system});
-    in
-    {
-      overlays.default = final: _prev: {
-        music-mirror = final.callPackage ./package.nix { };
-      };
-
-      packages = forAllSystems (pkgs: rec {
-        music-mirror = pkgs.callPackage ./package.nix { };
-        default = music-mirror;
-      });
-
-      # The package builds only if the test suite passes, so this covers both.
-      checks = forAllSystems (pkgs: { inherit (self.packages.${pkgs.system}) music-mirror; });
-
-      devShells = forAllSystems (pkgs: {
-        default = pkgs.mkShellNoCC {
-          packages = [
-            pkgs.python3
-            pkgs.python3Packages.pytest
-            pkgs.ffmpeg
-          ];
-        };
-      });
-
-      formatter = forAllSystems (pkgs: pkgs.nixfmt-tree);
-    };
-}

package.nix

@@ -1,51 +0,0 @@
-{
-  lib,
-  python3Packages,
-  makeWrapper,
-  ffmpeg,
-}:
-python3Packages.buildPythonApplication {
-  pname = "music-mirror";
-  inherit ((lib.importTOML ./pyproject.toml).project) version;
-  pyproject = true;
-
-  src = lib.fileset.toSource {
-    root = ./.;
-    fileset = lib.fileset.unions [
-      ./music_mirror.py
-      ./pyproject.toml
-      ./pytest.ini
-      ./tests
-    ];
-  };
-
-  build-system = [ python3Packages.setuptools ];
-  nativeBuildInputs = [ makeWrapper ];
-
-  # ffmpeg and ffprobe are called as subprocesses, so they belong on the
-  # wrapper's PATH rather than in the Python environment.
-  makeWrapperArgs = [
-    "--prefix"
-    "PATH"
-    ":"
-    (lib.makeBinPath [ ffmpeg ])
-  ];
-
-  nativeCheckInputs = [
-    python3Packages.pytestCheckHook
-    ffmpeg
-  ];
-
-  meta = {
-    description = "Maintain a lossy MP3 mirror of a lossless music library";
-    longDescription = ''
-      Reproduces a lossless library, path for path, as MP3 in a separate tree:
-      tags and cover art carried across, sources that are already MP3 copied
-      rather than re-encoded, and mirror files whose source has gone deleted.
-      The source library is never written to.
-    '';
-    homepage = "https://code.emmathe.dev/lyrathorpe/music-mirror";
-    mainProgram = "music-mirror";
-    platforms = lib.platforms.unix;
-  };
-}