replace file discovery by udp discovery

docker/leader-election.sh

@@ -2,9 +2,13 @@
 # =============================================================================
 # Leader Election Script for meta-core
 #
-# Uses flock for leader election. Only the leader runs the full application
-# stack (supervisord with Redis, meta-core, nginx, rclone, mount-watcher).
-# Followers remain dormant, periodically retrying to acquire the lock.
+# The flock here is a MUTEX, not service discovery. It is the only thing
+# stopping two containers that mount the same /meta-core volume from putting
+# two Redis writers on one RDB/AOF. Sibling services no longer read anything
+# from this directory — they locate meta-core over UDP (meta-discovery v1, see
+# docs/project-architecture/service-discovery.md), so the kv-leader.info file
+# this script used to publish is gone. Keep the lock; it costs nothing and the
+# corruption it prevents is unrecoverable.
 #
 # Environment variables:
 #   META_CORE_PATH         - Path to meta-core data directory (default: /meta-core)
@@ -20,7 +24,6 @@ META_CORE_HTTP_PORT="${META_CORE_HTTP_PORT:-9000}"
 ELECTION_RETRY_SECS="${ELECTION_RETRY_SECS:-5}"
 
 LOCK_FILE="${META_CORE_PATH}/locks/kv-leader.lock"
-INFO_FILE="${META_CORE_PATH}/locks/kv-leader.info"
 SUPERVISORD_CONF="/etc/supervisor/conf.d/supervisord.conf"
 
 # Get the container's IP address
@@ -40,35 +43,13 @@ get_local_ip() {
     echo "$ip"
 }
 
-# Write leader info file (plain text API URL)
-write_leader_info() {
-    local ip=$(get_local_ip)
-    local api_url="http://${ip}:${META_CORE_HTTP_PORT}"
-
-    # Write atomically using temp file + rename
-    local temp_file="${INFO_FILE}.tmp"
-    echo "$api_url" > "$temp_file"
-    mv "$temp_file" "$INFO_FILE"
-
-    echo "[election] Wrote leader info: $api_url"
-}
-
-# Clean up leader info file on shutdown
-cleanup() {
-    echo "[election] Cleaning up..."
-    rm -f "$INFO_FILE"
-    exit 0
-}
-
 # Set up signal handlers for graceful shutdown
-trap cleanup SIGTERM SIGINT
 
 # Ensure lock directory exists
 mkdir -p "$(dirname "$LOCK_FILE")"
 
 echo "[election] Starting leader election..."
 echo "[election] Lock file: $LOCK_FILE"
-echo "[election] Info file: $INFO_FILE"
 
 # Open lock file for flock (file descriptor 200)
 exec 200>"$LOCK_FILE"
@@ -79,9 +60,6 @@ while true; do
     if flock -n 200; then
         echo "[election] Acquired flock - transitioning to LEADER"
 
-        # Write leader info before starting services
-        write_leader_info
-
         # exec supervisord - replaces this process
         # When supervisord exits, the flock is released automatically
         echo "[election] Starting supervisord..."