Update Dockerfile

Dockerfile

@@ -1,19 +1,28 @@
-FROM rust AS builder
+FROM rust:slim AS builder
 
 WORKDIR /src/builder
 
+ARG TARGETARCH
+RUN if [ $TARGETARCH = "amd64" ]; then \
+        echo "x86_64" > /tmp/arch; \
+    elif [ $TARGETARCH = "arm64" ]; then \
+        echo "aarch64" > /tmp/arch; \
+    else \
+        echo "Unsupported platform"; \
+        exit 1; \
+    fi
+
 RUN apt-get update && apt-get install -y musl-tools
-RUN rustup target add aarch64-unknown-linux-musl
+RUN rustup target add $(cat /tmp/arch)-unknown-linux-musl
 
 COPY . .
-RUN --mount=type=cache,target=/src/builder/target/ cargo build --target=aarch64-unknown-linux-musl --release && \
-  cp target/aarch64-unknown-linux-musl/release/expander /tmp/expander
+RUN --mount=type=cache,target=/src/builder/target/ cargo build --target=$(cat /tmp/arch)-unknown-linux-musl --release && \
+  cp target/$(cat /tmp/arch)-unknown-linux-musl/release/expander /tmp/expander
 
-FROM alpine
+FROM scratch
 
 WORKDIR /src/app
 
-RUN apk add ca-certificates
 COPY --from=builder /tmp/expander .
 
 CMD ["./expander"]