build: don't use context for building Docker image

Use a provided VERSION argument to override the one in the Makefile.

.github/workflows/ci.yml

@@ -238,6 +238,10 @@ jobs:
         with:
           fetch-depth: 0
           persist-credentials: false
+      - name: Get version
+        id: version
+        run: |
+          echo version=$(make version) >> "$GITHUB_OUTPUT"
       - uses: docker/setup-qemu-action@v3
       - uses: docker/setup-buildx-action@v3
       - uses: docker/metadata-action@v5
@@ -256,9 +260,9 @@ jobs:
           registry: ghcr.io
           username: ${{ github.repository_owner }}
           password: ${{ secrets.GITHUB_TOKEN }}
-      - uses: docker/build-push-action@v6
+      - name: Build image
+        uses: docker/build-push-action@v6
         with:
-          context: .
           file: docker/Dockerfile
           platforms: |
             linux/amd64
@@ -266,6 +270,8 @@ jobs:
             linux/arm64
             linux/arm/v7
           push: true
+          build-args: |
+            VERSION=${{ steps.version.outputs.version }}
           tags: ${{ steps.meta.outputs.tags }}
           labels: ${{ steps.meta.outputs.labels }}
           annotations: ${{ steps.meta.outputs.annotations }}

docker/Dockerfile

@@ -18,6 +18,7 @@ RUN touch console/frontend/node_modules console/data/frontend .fmt-js~ .fmt.go~
 ARG TARGETOS
 ARG TARGETARCH
 ARG TARGETVARIANT
+ARG VERSION
 RUN make
 
 FROM gcr.io/distroless/static:latest

docker/Dockerfile.nix

@@ -4,7 +4,7 @@ RUN echo filter-syscalls = false >> /etc/nix/nix.conf
 WORKDIR /app
 COPY . .
 RUN mkdir -p /output/store
-RUN git describe --tags --always --dirty --match=v* > .version && git add -f .version
+RUN make version > .version && git add -f .version
 RUN nix run ".#update" \
  && nix run ".#build" \
  && cp -va $(nix-store -qR result) /output/store \