add option for following nightly yt-dlp releases (closes #999)

docker-entrypoint.sh

@@ -8,6 +8,48 @@ umask ${UMASK}
 echo "Creating download directory (${DOWNLOAD_DIR}), state directory (${STATE_DIR}), and temp dir (${TEMP_DIR})"
 mkdir -p "${DOWNLOAD_DIR}" "${STATE_DIR}" "${TEMP_DIR}"
 
+do_upgrade() {
+    echo "Upgrading yt-dlp to nightly channel..."
+    if ! python3 -m pip --version >/dev/null 2>&1; then
+        echo "pip not found; attempting ensurepip"
+        python3 -m ensurepip --upgrade >/dev/null 2>&1 || true
+    fi
+    if ! python3 -m pip install -U --pre "yt-dlp[default,curl-cffi,deno]"; then
+        echo "Warning: yt-dlp nightly upgrade failed; continuing with existing installation"
+        return 1
+    fi
+    echo "yt-dlp nightly upgrade complete"
+    return 0
+}
+
+run_supervised() {
+    while true; do
+        "$@" &
+        child_pid=$!
+        trap 'kill -TERM "$child_pid" 2>/dev/null; wait "$child_pid" 2>/dev/null' TERM INT
+        wait "$child_pid"
+        exit_code=$?
+        trap - TERM INT
+        if [ "$exit_code" -eq 42 ]; then
+            echo "MeTube requested yt-dlp update restart (exit 42)"
+            do_upgrade || true
+            continue
+        fi
+        return "$exit_code"
+    done
+}
+
+nightly_enabled() {
+    [ -n "${YTDL_NIGHTLY_UPDATE_TIME}" ]
+}
+
+disable_nightly_for_non_root() {
+    if nightly_enabled; then
+        echo "YTDL_NIGHTLY_UPDATE_TIME is set but this container runs as a non-root user; nightly yt-dlp updates are not supported. Ignoring YTDL_NIGHTLY_UPDATE_TIME."
+        unset YTDL_NIGHTLY_UPDATE_TIME
+    fi
+}
+
 if [ `id -u` -eq 0 ] && [ `id -g` -eq 0 ]; then
     if [ "${PUID}" -eq 0 ]; then
         echo "Warning: it is not recommended to run as root user, please check your setting of the PUID/PGID (or legacy UID/GID) environment variables"
@@ -16,13 +58,20 @@ if [ `id -u` -eq 0 ] && [ `id -g` -eq 0 ]; then
         echo "Changing ownership of download and state directories to ${PUID}:${PGID}"
         chown -R "${PUID}":"${PGID}" /app "${DOWNLOAD_DIR}" "${STATE_DIR}" "${TEMP_DIR}"
     fi
+    if nightly_enabled; then
+        echo "YTDL_NIGHTLY_UPDATE_TIME is set to ${YTDL_NIGHTLY_UPDATE_TIME}; upgrading yt-dlp on startup"
+        do_upgrade || true
+    fi
     echo "Starting BgUtils POT Provider"
     gosu "${PUID}":"${PGID}" bgutil-pot server >/tmp/bgutil-pot.log 2>&1 &
     echo "Running MeTube as user ${PUID}:${PGID}"
-    exec gosu "${PUID}":"${PGID}" python3 app/main.py
+    run_supervised gosu "${PUID}":"${PGID}" python3 app/main.py
+    exit $?
 else
     echo "User set by docker; running MeTube as `id -u`:`id -g`"
+    disable_nightly_for_non_root
     echo "Starting BgUtils POT Provider"
     bgutil-pot server >/tmp/bgutil-pot.log 2>&1 &
-    exec python3 app/main.py
+    run_supervised python3 app/main.py
+    exit $?
 fi