Update Dockerfile and GitHub Actions for multi-architecture support

- Modified Dockerfile to support architecture-specific artifact copying using the TARGETARCH argument.
- Enhanced the GitHub Actions workflow to dynamically set build arguments based on the target platform (amd64 or arm64).
- Ensured executable permissions for the copied artifact and set the entrypoint for the Docker container.

These changes improve the flexibility and efficiency of the Docker image build process across different architectures.

.github/workflows/build.yaml

@@ -149,6 +149,7 @@ jobs:
           push: true
           tags: ${{ steps.meta.outputs.tags }}
           labels: ${{ steps.meta.outputs.labels }}
+          build-args: TARGETARCH=${{ matrix.platform == 'linux/amd64' && 'amd64' || 'arm64' }}
           build-contexts: |
             amd64=./artifacts/flapi-linux-amd64
             arm64=./artifacts/flapi-linux-arm64

Dockerfile

@@ -1,5 +1,6 @@
-FROM ubuntu:24.04
+FROM ubuntu:24.04 AS base
 
+# Install runtime dependencies
 RUN apt-get update && apt-get install -y --no-install-recommends \
     libc6 \
     libstdc++6 \
@@ -8,7 +9,15 @@ RUN apt-get update && apt-get install -y --no-install-recommends \
     && rm -rf /var/lib/apt/lists/*
 
 WORKDIR /app
-COPY --from=build flapi /app/flapi
+
+# Default target architecture
+ARG TARGETARCH=amd64
+
+# Copy prebuilt artifact based on architecture
+COPY ./artifacts/flapi-linux-${TARGETARCH}/flapi /app/flapi
+
+# Ensure executable permissions
 RUN chmod +x /app/flapi
 
+# Set entrypoint
 ENTRYPOINT ["/app/flapi"]