Simplify startup and dependencies

Dockerfile

@@ -32,7 +32,10 @@ ENV S6_BEHAVIOUR_IF_STAGE2_FAILS=2 \
 
 SHELL ["/bin/bash", "-o", "pipefail", "-c"]
 
-COPY rootfs/ /
+# only copy files necessary for the build, copy whole rootfs later
+# this improves build caching when changing service and startup scripting
+COPY rootfs/tar1090-install.sh /
+COPY rootfs/etc/nginx.tar1090 /etc/nginx.tar1090
 
 # add telegraf binary
 ##telegraf##COPY --from=telegraf /usr/bin/telegraf /usr/bin/telegraf
@@ -178,6 +181,8 @@ RUN set -x && \
     popd && \
     rm -rf /tmp/*
 
+COPY rootfs/ /
+
 EXPOSE 80/tcp
 
 # Add healthcheck

rootfs/etc/s6-overlay/s6-rc.d/startup/up

@@ -0,0 +1,2 @@
+#!/bin/sh
+exec /etc/s6-overlay/scripts/startup

rootfs/etc/s6-overlay/scripts/readsb

@@ -323,4 +323,4 @@ if chk_enabled "$PROMETHEUS_ENABLE"; then
 fi
 
 # shellcheck disable=SC2086
-"${s6wrap[@]}" "${READSB_BIN}" "${READSB_CMD[@]}" $READSB_EXTRA_ARGS
+exec "${s6wrap[@]}" "${READSB_BIN}" "${READSB_CMD[@]}" $READSB_EXTRA_ARGS

rootfs/etc/s6-overlay/scripts/startup

@@ -0,0 +1,18 @@
+#!/command/with-contenv bash
+# shellcheck shell=bash disable=SC1091,SC2076
+
+source /scripts/common
+
+SDIR=/etc/s6-overlay/startup.d
+
+# exit 0 for nonexistent or empty directory
+if ! [[ -d "$SDIR" ]] || [[ -z "$(ls "$SDIR")" ]]; then
+    exit 0
+fi
+
+for NAME in "$SDIR"/*; do
+    if ! s6wrap --quiet --prepend="$NAME" --timestamps --args "$NAME"; then
+        s6wrap --quiet --prepend=startup --timestamps --args echo Error running "$NAME"
+        exit 1
+    fi
+done