Add ARM dependencies to metadata prefetch Dockerfile.

cmd/metadata_prefetch/Dockerfile

@@ -25,17 +25,28 @@ RUN make metadata-prefetch BINDIR=/bin
 # go/gke-releasing-policies#base-images
 FROM gke.gcr.io/debian-base:bookworm-v1.0.4-gke.2 AS debian
 
-# go/gke-releasing-policies#base-images
-FROM  gcr.io/distroless/base-debian12 AS output-image
+# The distroless amd64 image has a target triplet of x86_64
+FROM distroless-base AS distroless-amd64
+ENV LIB_DIR_PREFIX=x86_64
+ENV LD_LINUX_FILE=/lib64/ld-linux-x86-64.so.2
+ENV LIB_DIR=/lib64/
+
+# The distroless arm64 image has a target triplet of aarch64
+FROM distroless-base AS distroless-arm64
+ENV LIB_DIR_PREFIX aarch64
+ENV LD_LINUX_FILE /lib/ld-linux-aarch64.so.1
+ENV LIB_DIR /lib/
 
+# go/gke-releasing-policies#base-images
+FROM  distroless-$TARGETARCH AS output-image
 # Copy existing binaries.
 COPY --from=debian /bin/ls /bin/ls
 
 # Copy dependencies.
-COPY --from=debian /lib/x86_64-linux-gnu/libselinux.so.1 /lib/x86_64-linux-gnu/libselinux.so.1
-COPY --from=debian /lib/x86_64-linux-gnu/libc.so.6 /lib/x86_64-linux-gnu/libc.so.6
-COPY --from=debian /lib/x86_64-linux-gnu/libpcre2-8.so.0 /lib/x86_64-linux-gnu/libpcre2-8.so.0
-COPY --from=debian /lib64/ld-linux-x86-64.so.2 /lib64/ld-linux-x86-64.so.2 
+COPY --from=debian /lib/${LIB_DIR_PREFIX}-linux-gnu/libselinux.so.1 /lib/${LIB_DIR_PREFIX}-linux-gnu/libselinux.so.1
+COPY --from=debian /lib/${LIB_DIR_PREFIX}-linux-gnu/libc.so.6 /lib/${LIB_DIR_PREFIX}-linux-gnu/libc.so.6
+COPY --from=debian /lib/${LIB_DIR_PREFIX}-linux-gnu/libpcre2-8.so.0 /lib/${LIB_DIR_PREFIX}-linux-gnu/libpcre2-8.so.0
+COPY --from=debian ${LD_LINUX_FILE} ${LIB_DIR}
 
 # Validate dependencies
 FROM output-image AS validator-image