Simplify and validate Docker deployment

Dockerfile

@@ -1,17 +1,28 @@
 FROM golang:1.26 AS build
+
 WORKDIR /src
 COPY go.mod ./
 RUN go mod download
 COPY . .
-RUN CGO_ENABLED=0 go build -trimpath -ldflags="-s -w" -o /preface-tools ./cmd/preface-tools
+RUN CGO_ENABLED=0 go build -trimpath -ldflags="-s -w" -o /out/preface-tools ./cmd/preface-tools
-RUN CGO_ENABLED=0 go build -trimpath -ldflags="-s -w" -o /healthcheck ./cmd/healthcheck
+RUN CGO_ENABLED=0 go build -trimpath -ldflags="-s -w" -o /out/healthcheck ./cmd/healthcheck
+
+FROM alpine:3.21
+
+RUN apk add --no-cache ca-certificates \
+    && addgroup -S -g 10001 preface \
+    && adduser -S -D -H -u 10001 -G preface preface
 
-FROM gcr.io/distroless/static-debian12:nonroot
 WORKDIR /app
-COPY --from=build /preface-tools /usr/local/bin/preface-tools
+COPY --from=build /out/preface-tools /usr/local/bin/preface-tools
-COPY --from=build /healthcheck /usr/local/bin/healthcheck
+COPY --from=build /out/healthcheck /usr/local/bin/healthcheck
-COPY --from=build /src/prompts /app/prompts
+COPY --chown=preface:preface prompts /app/prompts
-VOLUME ["/app/data"]
+RUN mkdir -p /app/data/comic-animator/uploads /app/data/comic-animator/outputs \
+    && chown -R preface:preface /app/data
+
+USER preface
 EXPOSE 8080
-HEALTHCHECK --interval=30s --timeout=3s --start-period=10s --retries=3 CMD ["/usr/local/bin/healthcheck", "http://127.0.0.1:8080/readyz"]
+HEALTHCHECK --interval=30s --timeout=3s --start-period=10s --retries=3 \
+    CMD ["/usr/local/bin/healthcheck", "http://127.0.0.1:8080/readyz"]
+
 ENTRYPOINT ["/usr/local/bin/preface-tools"]

README.md

@@ -149,14 +149,13 @@ running process immediately.
    docker compose logs -f preface-tools
    ```
 
-4. Put a TLS reverse proxy in front of `127.0.0.1:8080`. The Compose file binds
+4. Put a TLS reverse proxy in front of port `8080`. The Compose file publishes
-   only to loopback deliberately. If TLS is terminated by an ingress on another
+   that port on the host. Restrict it with the host firewall if the server is on
-   host, adjust the `ports` mapping or use an external Docker network while
+   an untrusted network, or change the mapping to `127.0.0.1:8080:8080` after
-   keeping the application container otherwise private.
+   confirming loopback Docker forwarding works on the deployment host.
 
-The container runs as a non-root user with all Linux capabilities dropped, a
+The container runs as a dedicated non-root user and stores runtime data in a
-read-only root filesystem, `no-new-privileges`, and a named volume for runtime
+named volume. It exposes:
-data. It exposes:
 
 - `GET /healthz` for liveness;
 - `GET /readyz` for readiness.

compose.yml

@@ -1,12 +1,9 @@
 services:
   preface-tools:
-    build:
+    build: .
-      context: .
     image: preface-tools:local
     restart: unless-stopped
-    init: true
+    env_file: .env
-    env_file:
-      - .env
     environment:
       APP_ENV: production
       HTTP_ADDRESS: :8080
@@ -14,23 +11,10 @@ services:
       COMIC_ANIMATOR_UPLOAD_DIR: /app/data/comic-animator/uploads
       COMIC_ANIMATOR_OUTPUT_DIR: /app/data/comic-animator/outputs
     ports:
-      - "127.0.0.1:8080:8080"
+      - "8080:8080"
     volumes:
       - preface-data:/app/data
       - ./prompts:/app/prompts:ro
-    read_only: true
-    tmpfs:
-      - /tmp:size=64m,mode=1777
-    cap_drop:
-      - ALL
-    security_opt:
-      - no-new-privileges:true
-    healthcheck:
-      test: ["CMD", "/usr/local/bin/healthcheck", "http://127.0.0.1:8080/readyz"]
-      interval: 30s
-      timeout: 3s
-      start_period: 10s
-      retries: 3
 
 volumes:
   preface-data: