fix(replicas): reach publisher via unix socket or sudo postgres

TCP 127.0.0.1:15432 is often closed; the cluster listens on a unix
socket. Fall back to /var/run/postgresql then runuser -u postgres.

Co-authored-by: Cursor <cursoragent@cursor.com>

deploy/sync-replica-data.sh

@@ -81,6 +81,9 @@ resolve_publisher_dsn() {
 }
 
 PUBLISHER="$(resolve_publisher_dsn)" || exit 1
+PUBLISHER_MODE="dsn"
+PUB_PORT=""
+PUB_DB="superadmin"
 
 mapfile -t REPLICAS < <(
   printf '%s\n' "$REPLICA_DSNS" | tr ',' '\n' | sed 's/^[[:space:]]*//;s/[[:space:]]*$//' | grep -v '^$'
@@ -107,14 +110,91 @@ label() {
   echo "${host:-?}:${port:-5432}/${db:-?}"
 }
 
-if ! run_psql "$(libpq_dsn "$PUBLISHER")" -v ON_ERROR_STOP=1 -At -c "SELECT 1" >/dev/null 2>&1; then
-  echo "Cannot connect to publisher ($(label "$PUBLISHER"))." >&2
-  echo "Add PUBLISHER_DSN to deploy/replicas.env — URL-encode @ in passwords as %40." >&2
-  exit 1
+as_postgres() {
+  if command -v runuser >/dev/null; then
+    runuser -u postgres -- "$@"
+  else
+    sudo -n -u postgres -- "$@"
   fi
+}
+
+publisher_port() {
+  local src="${PUBLISHER:-}${DATABASE_URL:-}"
+  if [[ "$src" =~ :([0-9]{4,5})/ ]]; then
+    echo "${BASH_REMATCH[1]}"
+    return
+  fi
+  if [[ "$src" =~ port=([0-9]+) ]]; then
+    echo "${BASH_REMATCH[1]}"
+    return
+  fi
+  echo "15432"
+}
+
+probe_dsn() {
+  local dsn="$1"
+  run_psql "$(libpq_dsn "$dsn")" -v ON_ERROR_STOP=1 -At -c "SELECT 1" >/dev/null
+}
+
+connect_publisher() {
+  PUB_PORT="$(publisher_port)"
+  echo "publisher probe port=$PUB_PORT dsn=$(label "$PUBLISHER")"
+
+  if probe_dsn "$PUBLISHER"; then
+    PUBLISHER_MODE="dsn"
+    echo "publisher: TCP/DSN ok"
+    return 0
+  fi
+  echo "publisher: TCP/DSN failed (cluster is often unix-socket only on this host)"
+
+  local sock="host=/var/run/postgresql port=${PUB_PORT} dbname=${PUB_DB} user=postgres"
+  if probe_dsn "$sock"; then
+    PUBLISHER="$sock"
+    PUBLISHER_MODE="socket"
+    echo "publisher: unix socket as postgres ok"
+    return 0
+  fi
+
+  if as_postgres psql -p "$PUB_PORT" -d "$PUB_DB" -v ON_ERROR_STOP=1 -At -c "SELECT 1" </dev/null >/dev/null; then
+    PUBLISHER_MODE="sudo"
+    echo "publisher: runuser/sudo -u postgres ok (port $PUB_PORT)"
+    return 0
+  fi
+
+  echo "Cannot connect to publisher." >&2
+  echo "Tried: $(label "$PUBLISHER")  then unix socket  then sudo -u postgres -p $PUB_PORT" >&2
+  echo "Debug:" >&2
+  run_psql "$(libpq_dsn "$PUBLISHER")" -c "SELECT 1" || true
+  as_postgres psql -p "$PUB_PORT" -d "$PUB_DB" -c "SELECT 1" || true
+  ss -lntp 2>/dev/null | grep -E "$PUB_PORT|postgres" || netstat -lntp 2>/dev/null | grep postgres || true
+  exit 1
+}
+
+publisher_psql() {
+  if [[ "$PUBLISHER_MODE" == "sudo" ]]; then
+    as_postgres psql -p "$PUB_PORT" -d "$PUB_DB" "$@" </dev/null
+  else
+    run_psql "$(libpq_dsn "$PUBLISHER")" "$@"
+  fi
+}
+
+publisher_dump() {
+  if [[ "$PUBLISHER_MODE" == "sudo" ]]; then
+    as_postgres pg_dump -p "$PUB_PORT" -d "$PUB_DB" "$@"
+  else
+    pg_dump "$(libpq_dsn "$PUBLISHER")" "$@"
+  fi
+}
+
+connect_publisher
 
 table_count() {
   local dsn="$1" table="$2"
+  if [[ "$dsn" == "$PUBLISHER" ]]; then
+    publisher_psql -v ON_ERROR_STOP=1 -At -c \
+      "SELECT count(*)::bigint FROM public.\"$table\""
+    return
+  fi
   run_psql "$(libpq_dsn "$dsn")" -v ON_ERROR_STOP=1 -At -c \
     "SELECT count(*)::bigint FROM public.\"$table\""
 }
@@ -157,7 +237,7 @@ copy_table_from_publisher() {
   local replica_dsn="$1" table="$2"
   local dump
   dump="$(mktemp)"
-  pg_dump "$(libpq_dsn "$PUBLISHER")" \
+  publisher_dump \
     -t "$table" \
     --data-only \
     --no-owner \