fix installing dumb-init in arm64 image (#1525)

dist/images/Dockerfile.base

@@ -76,7 +76,10 @@ RUN --mount=type=bind,target=/packages,from=ovs-builder,source=/packages  \
     dpkg -i /packages/python3-openvswitch*.deb &&\
     dpkg -i --ignore-depends=openvswitch-switch,openvswitch-common /packages/ovn-*.deb
 
-RUN curl -sSf -L --retry 5 -o /usr/bin/dumb-init https://github.com/Yelp/dumb-init/releases/download/v1.2.5/dumb-init_1.2.5_x86_64
-RUN chmod +x /usr/bin/dumb-init
+ENV DUMB_INIT_VERSION="1.2.5"
+RUN dump_arch="x86_64"; \
+    if [ "$ARCH" = "arm64" ]; then dump_arch="aarch64"; fi; \
+    curl -sSf -L --retry 5 -o /usr/bin/dumb-init https://github.com/Yelp/dumb-init/releases/download/v${DUMB_INIT_VERSION}/dumb-init_${DUMB_INIT_VERSION}_${dump_arch} && \
+    chmod +x /usr/bin/dumb-init
 
 ENTRYPOINT ["/usr/bin/dumb-init", "--"]