Let push_desktop.sh copy the feed to a remote deploy checkout

--host user@server:/path syncs deploy/data/desktop to the same path on the
server with rsync, falling back to tar over ssh when the server has no
rsync. A failed transfer now exits non-zero instead of claiming the feed is
live.

deploy/push_desktop.sh

@@ -1,28 +1,40 @@
 #!/bin/bash
-# Build the J621 desktop packages and publish them to the frontend's update
-# feed (deploy/data/desktop, mounted read-only into the frontend nginx and
-# served at /desktop/). electron-updater reads latest-linux.yml / latest.yml
-# from there; the app's feed URL comes from desktop/electron-builder.yml.
+# Build the J621 desktop packages and publish them to the update feed.
 #
-# Usage: ./push_desktop.sh [--win] [--no-build]
+# Locally the feed is deploy/data/desktop, which the frontend nginx mounts
+# read-only and serves at /desktop/. With --host the same directory is also
+# copied to a remote deploy checkout (rsync, or tar over ssh when the server
+# has no rsync). electron-updater reads latest-linux.yml / latest.yml from
+# there; the feed URL comes from desktop/electron-builder.yml.
+#
+# Usage: ./push_desktop.sh [--win] [--no-build] [--host user@server:/path]
 #   --win       also cross-build the Windows NSIS installer (needs wine)
 #   --no-build  publish what is already in desktop/release/
+#   --host      remote deploy checkout, e.g. jakerasp:/home/jake/servers/J621
 set -euo pipefail
 cd "$(dirname "$0")/.."
 
 BUILD=1
 WIN=0
-for arg in "$@"; do
-    case "$arg" in
+REMOTE=""
+while [ $# -gt 0 ]; do
+    case "$1" in
         --win) WIN=1 ;;
         --no-build) BUILD=0 ;;
+        --host) REMOTE="${2:?--host needs user@server:/path}"; shift ;;
         *)
-            echo "usage: $0 [--win] [--no-build]" >&2
+            echo "usage: $0 [--win] [--no-build] [--host user@server:/path]" >&2
             exit 2
             ;;
     esac
+    shift
 done
 
+if [ -n "$REMOTE" ] && [ "$REMOTE" = "${REMOTE#*:}" ]; then
+    echo "--host needs user@server:/path (got '$REMOTE')" >&2
+    exit 2
+fi
+
 if [ "$BUILD" = 1 ]; then
     echo "==> Building Linux packages (deb + pacman) ..."
     npm --prefix desktop run dist:linux
@@ -57,6 +69,36 @@ fi
 
 echo "==> Published to $FEED:"
 ls -1sh "$FEED" | sed 's/^/    /'
+
+if [ -n "$REMOTE" ]; then
+    REMOTE_TARGET="${REMOTE%%:*}"
+    REMOTE_ROOT="${REMOTE#*:}"
+    REMOTE_FEED="${REMOTE_ROOT%/}/deploy/data/desktop"
+
+    echo
+    echo "==> Copying the feed to $REMOTE_TARGET:$REMOTE_FEED ..."
+    transferred=0
+    if command -v rsync >/dev/null 2>&1; then
+        if rsync -a --info=progress2 "$FEED"/ "$REMOTE_TARGET:$REMOTE_FEED/"; then
+            transferred=1
+        else
+            echo "==> rsync did not work (missing on the server?); trying tar over ssh ..."
+        fi
+    fi
+    if [ "$transferred" -eq 0 ]; then
+        if ! ssh "$REMOTE_TARGET" "mkdir -p '$REMOTE_FEED'"; then
+            echo "ssh to $REMOTE_TARGET failed; nothing was copied." >&2
+            exit 1
+        fi
+        if ! tar -C "$FEED" -cf - . |
+            ssh "$REMOTE_TARGET" "tar -C '$REMOTE_FEED' -xf -"; then
+            echo "Copy to $REMOTE_TARGET:$REMOTE_FEED failed." >&2
+            exit 1
+        fi
+    fi
+    echo "==> Feed live at $REMOTE_TARGET:$REMOTE_FEED (no restart needed)."
+fi
+
 echo
 echo "Served read-only by the frontend nginx at /desktop/ (no restart needed):"
 echo "    https://<frontend-host>/desktop/latest-linux.yml"