make timelapse1090 load on demand

instead of timelapse1090 being part of the image, just install it on
image startup if the option is enabled

this saves 12 MB image size

Dockerfile

@@ -84,14 +84,6 @@ RUN set -x && \
     rm -rf "${TAR1090_UPDATE_DIR}" && \
     # tar1090: add nginx config
     cp -Rv /etc/nginx.tar1090/* /etc/nginx/ && \
-    # timelapse1090
-    git clone --single-branch --depth 1 "https://github.com/wiedehopf/timelapse1090.git" "${GITPATH_TIMELAPSE1090}" && \
-    pushd "${GITPATH_TIMELAPSE1090}" && \
-    bash -ec 'echo "timelapse1090 $(git log | head -1 | tr -s " " "_")" >> /VERSIONS' && \
-    # remove unused .git dir to slightly reduce image size
-    rm -rf "${GITPATH_TIMELAPSE1090}/.git" && \
-    popd && \
-    mkdir -p /var/timelapse1090 && \
     # aircraft-db, file in TAR1090_UPDATE_DIR will be preferred when starting readsb if tar1090-update enabled
     curl -o "${TAR1090_INSTALL_DIR}/aircraft.csv.gz" "https://raw.githubusercontent.com/wiedehopf/tar1090-db/csv/aircraft.csv.gz" && \
     # clone graphs1090 repo

rootfs/etc/s6-overlay/startup.d/11-timelapse1090

@@ -0,0 +1,21 @@
+#!/command/with-contenv bash
+# shellcheck shell=bash disable=SC1091,SC2015,SC2153
+
+source /scripts/common
+
+if ! chk_enabled "${ENABLE_TIMELAPSE1090}" || chk_enabled "${TAR1090_DISABLE}"; then
+    exit 0
+fi
+
+if [[ -d "${GITPATH_TIMELAPSE1090}" ]]; then
+    exit 0
+fi
+
+# timelapse1090
+git clone --single-branch --depth 1 "https://github.com/wiedehopf/timelapse1090.git" "${GITPATH_TIMELAPSE1090}"
+pushd "${GITPATH_TIMELAPSE1090}"
+bash -ec 'echo "timelapse1090 $(git log | head -1 | tr -s " " "_")" >> /VERSIONS'
+# remove unused .git dir to slightly reduce image size
+rm -rf "${GITPATH_TIMELAPSE1090}/.git"
+popd
+mkdir -p /var/timelapse1090