Use tini as docker entrypoint

Dockerfile

@@ -71,7 +71,8 @@ RUN apk add --no-cache \
      inotify-tools \
      socat \
      bash \
-     zlib-dev
+     zlib-dev \
+     tini
 
 ENV GLIBC_VERSION 2.27-r0
 ENV GLIBC_SHA256 938bceae3b83c53e7fa9cc4135ce45e04aae99256c5e74cf186c794b97473bc7
@@ -99,4 +100,4 @@ COPY --from=builder /opt/litecoin/bin /usr/bin
 COPY tools/docker-entrypoint.sh entrypoint.sh
 
 EXPOSE 9735 9835
-ENTRYPOINT  [ "./entrypoint.sh" ]
+ENTRYPOINT  [ "/sbin/tini", "-g", "--", "./entrypoint.sh" ]

contrib/linuxarm32v7.Dockerfile

@@ -14,6 +14,10 @@ RUN set -ex \
 
 WORKDIR /opt
 
+RUN wget -qO /opt/tini "https://github.com/krallin/tini/releases/download/v0.18.0/tini-armhf" \
+    && echo "01b54b934d5f5deb32aa4eb4b0f71d0e76324f4f0237cc262d59376bf2bdc269 /opt/tini" | sha256sum -c - \
+    && chmod +x /opt/tini
+
 ARG BITCOIN_VERSION=0.17.0
 ENV BITCOIN_TARBALL bitcoin-$BITCOIN_VERSION-arm-linux-gnueabihf.tar.gz
 ENV BITCOIN_URL https://bitcoincore.org/bin/bitcoin-core-$BITCOIN_VERSION/$BITCOIN_TARBALL
@@ -91,6 +95,7 @@ RUN ./configure --prefix=/tmp/lightning_install --enable-static && make -j3 DEVE
 
 FROM arm32v7/debian:stretch-slim as final
 COPY --from=downloader /usr/bin/qemu-arm-static /usr/bin/qemu-arm-static
+COPY --from=downloader /opt/tini /usr/bin/tini
 RUN apt-get update && apt-get install -y --no-install-recommends socat inotify-tools \
     && rm -rf /var/lib/apt/lists/* 
 
@@ -106,4 +111,4 @@ COPY --from=downloader /opt/litecoin/bin /usr/bin
 COPY tools/docker-entrypoint.sh entrypoint.sh
 
 EXPOSE 9735 9835
-ENTRYPOINT  [ "./entrypoint.sh" ]
+ENTRYPOINT  [ "/usr/bin/tini", "-g", "--", "./entrypoint.sh" ]