contrib: add cln-plugin-bounce

Stopping a dynamic plugin requires its exact registered name, which
for versioned installs includes the version string.  cln-plugin-bounce
looks each name up from plugin list, stops the named plugins in the
order given, and starts them again in reverse order, so the list order
encodes any shutdown dependency between them.  Restarts prefer the
unversioned sibling path (usually a symlink maintained by the install
script) so a repointed symlink brings up the new version.  Plugin
names are the arguments without a leading dash; everything else passes
through to lightning-cli, so names and options may appear in any
order.  A script works under sudo where a shell alias does not.

contrib/README.md

@@ -60,6 +60,8 @@ cd contrib/
 
 ./clboss-askrene-layer-summary
 
+./cln-plugin-bounce <plugin-name>...
+
 The `clboss-routing-stats` and `clboss-forwarding-stats` scripts now accept `--days` to limit
 how many days of earnings history are considered when ranking channels.
 
@@ -83,6 +85,19 @@ how many days of earnings history are considered when ranking channels.
   with `--top N` resolving the busiest directions to node aliases.  Works on
   any persistent layer (`clboss` by default) and can replay a captured
   `askrene-listlayers` dump offline via `--input`.
+- **`cln-plugin-bounce`** stops and restarts running plugins without
+  restarting `lightningd`.  `plugin stop` needs a plugin's exact
+  registered name, which for versioned installs includes the version
+  string; the script looks each one up from `plugin list`, stops the
+  named plugins in the order given, and starts them again in reverse
+  order, so the list order encodes any shutdown dependency between
+  them.  Restarts use the unversioned sibling path when one exists
+  (usually a symlink maintained by the install script), so a repointed
+  symlink brings up the new version.  Plugin names are the arguments
+  not starting with `-`; every other argument is passed to
+  `lightning-cli` (e.g. `--signet --lightning-dir=...`), so names and
+  options may appear in any order.  Plain POSIX sh plus `jq`, so unlike
+  a shell alias it also works under `sudo`.
 - **`fee-log-parser`** is a parser that streams DEBUG-level logging and writes
   a sqlite database containing fee algorithm information. CLBOSS now records
   the same schema in its internal database (`data.clboss`, tables

contrib/cln-plugin-bounce

@@ -0,0 +1,134 @@
+#!/bin/sh
+# cln-plugin-bounce - stop and restart running CLN plugins without
+# restarting lightningd.
+#
+# usage: cln-plugin-bounce [lightning-cli options...] <plugin-name>...
+#
+# "plugin stop" requires a plugin's exact registered name, which for
+# versioned installs includes the version string (e.g.
+# /usr/local/bin/xrebalance-v0.4.1).  This script looks each exact
+# name up from "plugin list", stops the plugins in the order given,
+# then starts them again in reverse order, so the list order encodes
+# any shutdown dependency between them.  When an unversioned sibling
+# path exists (usually a symlink maintained by the install script),
+# the restart uses that, so a repointed symlink brings up the new
+# version.
+#
+# Plugin names are the arguments that do not start with "-"; each is
+# a short name ("clboss", "xrebalance"), or a full versioned basename
+# if the short name matches more than one running plugin.  All other
+# arguments are passed to every lightning-cli call, so names and
+# options may appear in any order:
+#   cln-plugin-bounce --signet --lightning-dir="$CLNDIR" xrebalance clboss
+# Set $LIGHTNING_CLI to override the lightning-cli binary.
+
+set -eu
+
+me=${0##*/}
+
+names=
+rebuilt=
+for arg do
+	[ -n "$rebuilt" ] || { set --; rebuilt=1; }
+	if [ "${arg#-}" = "$arg" ]; then
+		names="${names}${arg}
+"
+	else
+		set -- "$@" "$arg"
+	fi
+done
+
+if [ -z "$names" ]; then
+	echo "usage: $me [lightning-cli options...] <plugin-name>..." >&2
+	exit 2
+fi
+
+lcli=${LIGHTNING_CLI:-lightning-cli}
+
+if ! command -v jq >/dev/null; then
+	echo "$me: jq is required" >&2
+	exit 1
+fi
+
+# Registered paths whose basename is <name> or <name>-<anything>.
+match='.plugins[].name
+	| select((sub(".*/"; "")) as $b
+		| $b == $n or ($b | startswith($n + "-")))'
+
+# Resolve every name before touching anything, from one snapshot.
+plugins=$("$lcli" "$@" plugin list)
+
+resolved=
+while IFS= read -r n; do
+	[ -n "$n" ] || continue
+	running=$(printf '%s\n' "$plugins" | jq -r --arg n "$n" "$match")
+	if [ -z "$running" ]; then
+		echo "$me: no running plugin matches '$n'" >&2
+		exit 1
+	fi
+	if [ "$(printf '%s\n' "$running" | wc -l)" -gt 1 ]; then
+		echo "$me: '$n' matches more than one running plugin:" >&2
+		printf '%s\n' "$running" >&2
+		exit 1
+	fi
+	resolved="${resolved}${n} ${running}
+"
+done <<EOF
+$names
+EOF
+
+# Stop in the order given.
+stopped_names=
+tostart=
+while read -r n path; do
+	[ -n "$n" ] || continue
+	echo "stopping $path"
+	if ! "$lcli" "$@" plugin stop "$path" >/dev/null; then
+		echo "$me: stop failed for $path" >&2
+		if [ -n "$stopped_names" ]; then
+			echo "$me: already stopped, not restarted:$stopped_names" >&2
+		fi
+		exit 1
+	fi
+	stopped_names="$stopped_names $n"
+	tostart="${n} ${path}
+${tostart}"
+done <<EOF
+$resolved
+EOF
+
+# Start in reverse order, preferring the unversioned sibling; fall
+# back to the exact path that was stopped.
+failed=
+while read -r n path; do
+	[ -n "$n" ] || continue
+	start=$(dirname "$path")/$n
+	[ -e "$start" ] || start=$path
+	echo "starting $start"
+	if ! "$lcli" "$@" plugin start "$start" >/dev/null; then
+		ok=
+		if [ "$start" != "$path" ]; then
+			echo "$me: start failed; retrying with $path" >&2
+			if "$lcli" "$@" plugin start "$path" >/dev/null; then
+				ok=1
+			fi
+		fi
+		if [ -z "$ok" ]; then
+			echo "$me: failed to start $n" >&2
+			failed=1
+		fi
+	fi
+done <<EOF
+$tostart
+EOF
+
+plugins=$("$lcli" "$@" plugin list)
+while IFS= read -r n; do
+	[ -n "$n" ] || continue
+	printf '%s\n' "$plugins" | jq -r --arg n "$n" "$match" \
+		| sed 's/^/now running /'
+done <<EOF
+$names
+EOF
+
+[ -z "$failed" ] || exit 1