feat: add support for linux/arm64 image

.github/workflows/docker.yml

@@ -18,6 +18,7 @@ jobs:
     strategy:
       matrix:
         platform:
+          - linux/arm64
           - linux/amd64
 
     steps:

Dockerfile

@@ -1,17 +1,27 @@
-FROM --platform=amd64 rust:1.72-alpine as builder
+FROM rust:1.72-slim as builder
+ARG TARGETPLATFORM
 WORKDIR /build
 
-# RUN apt-get update && apt-get install -y build-essential musl-dev musl-tools gcc-x86-64-linux-gnu && apt-get clean && rm -rf /var/lib/apt/lists/*
-RUN apk update && apk upgrade && apk add --no-cache musl-dev
-RUN rustup target add x86_64-unknown-linux-musl
+RUN set -ex; \
+    case "$TARGETPLATFORM" in \
+        "linux/amd64") target='x86_64-unknown-linux-musl' ;; \
+        "linux/arm64") target='aarch64-unknown-linux-musl' ;; \
+        *) echo >&2 "error: unsupported $TARGETPLATFORM architecture"; exit 1 ;; \
+    esac; \
+    echo "$target" > /tmp/target-spec
+
+RUN apt-get update && apt-get install -y build-essential musl-dev musl-tools && apt-get clean && rm -rf /var/lib/apt/lists/*
+# RUN apk update && apk upgrade && apk add --no-cache musl-dev
+RUN rustup target add "$(cat /tmp/target-spec)"
 
 ENV CARGO_BUILD_RUSTFLAGS="-C target-feature=+crt-static"
 
 COPY . .
-RUN cargo fetch --target x86_64-unknown-linux-musl --locked
-RUN cargo build --target x86_64-unknown-linux-musl --release --locked
+RUN cargo fetch --target "$(cat /tmp/target-spec)" --locked
+RUN cargo build --target "$(cat /tmp/target-spec)" --release --locked
+RUN cp "/build/target/$(cat /tmp/target-spec)/release/valfisk" /build/valfisk
 
 FROM gcr.io/distroless/static:latest
-COPY --from=builder /build/target/x86_64-unknown-linux-musl/release/valfisk /valfisk
 
+COPY --from=builder /build/valfisk /valfisk
 CMD ["/valfisk"]