Update Dockerfile

Dockerfile

@@ -20,6 +20,11 @@ FROM alpine:latest
 
 WORKDIR /app
 
+# Receive PORT build arg from Coolify / Docker Compose (defaults to 8080 if unset)
+ARG PORT=8080
+# Set PORT environment variable for runtime, HEALTHCHECK, and Go application
+ENV PORT=${PORT}
+
 # Install runtime dependencies
 RUN apk add --no-cache ca-certificates tzdata
 
@@ -37,9 +42,9 @@ RUN addgroup -g 1000 appuser && \
 
 USER appuser
 
-EXPOSE 8080
+EXPOSE ${PORT}
 
 HEALTHCHECK --interval=30s --timeout=3s --start-period=5s --retries=3 \
-    CMD wget --quiet --tries=1 --spider http://localhost:8080/ || exit 1
+    CMD wget --quiet --tries=1 --spider http://localhost:${PORT}/ || exit 1
 
 CMD ["./blogging-cms"]