install s6 overlay during normal dependency setup

docker/Dockerfiles/Dockerfile-base

@@ -1,15 +1,12 @@
 FROM debian:buster-slim
 
-ADD docker/scripts/install-s6.sh /
-RUN /install-s6.sh && \
-    rm /install-s6.sh
-ENTRYPOINT ["/init"]
-
 ADD docker/files/js8call/js8call-hamlib.patch /
 ADD docker/scripts/install-dependencies.sh /
 RUN /install-dependencies.sh && \
     rm /install-dependencies.sh
 
+ENTRYPOINT ["/init"]
+
 WORKDIR /opt/openwebrx
 
 VOLUME /etc/openwebrx

docker/scripts/install-dependencies.sh

@@ -24,6 +24,24 @@ BUILD_PACKAGES="wget git libsndfile1-dev libfftw3-dev cmake make gcc g++ liblapa
 apt-get update
 apt-get -y install --no-install-recommends $STATIC_PACKAGES $BUILD_PACKAGES
 
+case `uname -m` in
+    arm*)
+        PLATFORM=armhf
+        ;;
+    aarch64*)
+        PLATFORM=aarch64
+        ;;
+    x86_64*)
+        PLATFORM=amd64
+        ;;
+esac
+
+pushd /tmp
+wget https://github.com/just-containers/s6-overlay/releases/download/v1.21.8.0/s6-overlay-${PLATFORM}.tar.gz
+tar xzf s6-overlay-${PLATFORM}.tar.gz -C /
+rm s6-overlay-${PLATFORM}.tar.gz
+popd
+
 git clone https://github.com/jketterl/js8py.git
 pushd js8py
 git checkout 888e62be375316882ad2b2ac8e396c3bf857b6fc

docker/scripts/install-s6.sh

@@ -1,29 +0,0 @@
-#!/usr/bin/env bash
-set -eux pipefail
-
-BUILD_PACKAGES="wget ca-certificates"
-
-apt-get update
-apt-get -y install --no-install-recommends $BUILD_PACKAGES
-
-case `uname -m` in
-    arm*)
-        PLATFORM=armhf
-        ;;
-    aarch64*)
-        PLATFORM=aarch64
-        ;;
-    x86_64*)
-        PLATFORM=amd64
-        ;;
-esac
-
-pushd /tmp
-wget https://github.com/just-containers/s6-overlay/releases/download/v1.21.8.0/s6-overlay-${PLATFORM}.tar.gz
-tar xzf s6-overlay-${PLATFORM}.tar.gz -C /
-rm s6-overlay-${PLATFORM}.tar.gz
-popd
-
-apt-get -y purge --autoremove $BUILD_PACKAGES
-apt-get clean
-rm -rf /var/lib/apt/lists/*