BE: Build Docker cnt in GH action

Author: justuswilhelm

.github/workflows/build-projectify-backend.yml

@@ -0,0 +1,22 @@
+name: Build docker image
+
+on:
+    push:
+    pull_request:
+jobs:
+    build:
+        runs-on: ubuntu-latest
+        steps:
+        - uses: actions/checkout@v4
+        -
+            name: Set up Docker Buildx
+            uses: docker/setup-buildx-action@v3
+        -
+            uses: docker/build-push-action@v6
+            with:
+                context: "{{defaultContext}}:backend"
+                push: false
+                load: true
+                file: projectify-backend.Dockerfile
+                cache-from: type=gha
+                cache-to: type=gha,mode=max

backend/flake.nix

@@ -78,9 +78,11 @@
           groups = [ ];
           outputs = [ "out" "static" ];
           postInstall = ''
-            mkdir -p $out/bin
+            mkdir -p $out/bin $out/etc
             cp manage.py "$out/bin"
 
+            cp gunicorn.conf.py gunicorn-error.log $out/etc/
+
             mkdir -p $static
             env \
               DJANGO_SETTINGS_MODULE=projectify.settings.collect_static \

backend/projectify-backend.Dockerfile

@@ -0,0 +1,19 @@
+FROM docker.io/nixos/nix:2.22.3 as builder
+
+COPY . /tmp/build
+WORKDIR /tmp/build
+
+# https://marcopolo.io/code/nix-and-small-containers/
+# https://mitchellh.com/writing/nix-with-dockerfiles
+RUN echo "experimental-features = nix-command flakes" > /etc/nix/nix.conf \
+    && nix build .#projectify-backend .#projectify-backend.static \
+    && cp -a "$(nix-store -qR result/)" /tmp/nix-store-closure
+
+FROM scratch
+WORKDIR /app
+COPY --from=builder /tmp/nix-store-closure /nix/store
+COPY --from=builder /tmp/build/result /app
+COPY --from=builder /tmp/build/result-1-static /static
+ENV STATIC_ROOT=/static
+
+CMD ["gunicorn", "--config", "/app/etc/gunicorn.conf.py", "--log-config", "/app/etc/gunicorn-error.log"]