Important plugin

Makefile

@@ -268,6 +268,15 @@ include tools/Makefile
 include plugins/Makefile
 include tests/plugins/Makefile
 
+# Generated from PLUGINS definition in plugins/Makefile
+gen_list_of_builtin_plugins.h : plugins/Makefile Makefile
+	@echo GEN $@
+	@rm -f $@ || true
+	@echo 'static const char *list_of_builtin_plugins[] = {' >> $@
+	@echo '$(PLUGINS)' | sed 's@plugins/\([^ 	]*\)@"\1",@g'>> $@
+	@echo 'NULL' >> $@
+	@echo '};' >> $@
+
 # Git doesn't maintain timestamps, so we only regen if git says we should.
 CHANGED_FROM_GIT = [ x"`git log $@ | head -n1`" != x"`git log $< | head -n1`" -o x"`git diff $<`" != x"" ]
 

doc/lightningd-config.5

@@ -534,10 +534,11 @@ add multiple directories\.
 
 
  \fBclear-plugins\fR
-This option clears all \fIplugin\fR and \fIplugin-dir\fR options preceeding it,
+This option clears all \fIplugin\fR, \fIimportant-plugin\fR, and \fIplugin-dir\fR options
+preceeding it,
 including the default built-in plugin directory\. You can still add
-\fIplugin-dir\fR and \fIplugin\fR options following this and they will have the
-normal effect\.
+\fIplugin-dir\fR, \fIplugin\fR, and \fIimportant-plugin\fR options following this
+and they will have the normal effect\.
 
 
  \fBdisable-plugin\fR=\fIPLUGIN\fR
@@ -547,6 +548,18 @@ be loaded at startup, whatever directory it is in\.  This option is useful for
 disabling a single plugin inside a directory\.  You can still explicitly
 load plugins which have been disabled, using \fBlightning-plugin\fR(7) \fBstart\fR\.
 
+
+ \fBimportant-plugin\fR=\fIPLUGIN\fR
+Speciy a plugin to run as part of C-lightning\.
+This can be specified multiple times to add multiple plugins\.
+Plugins specified via this option are considered so important, that if the
+plugin stops for any reason (including via \fBlightning-plugin\fR(7) \fBstop\fR),
+C-lightning will also stop running\.
+This way, you can monitor crashes of important plugins by simply monitoring
+if C-lightning terminates\.
+Built-in plugins, which are installed with \fBlightningd\fR(8), are automatically
+considered important\.
+
 .SH BUGS
 
 You should report bugs on our github issues page, and maybe submit a fix

doc/lightningd-config.5.md

@@ -439,10 +439,11 @@ loaded. *DIRECTORY* must exist; this can be specified multiple times to
 add multiple directories.
 
  **clear-plugins**
-This option clears all *plugin* and *plugin-dir* options preceeding it,
+This option clears all *plugin*, *important-plugin*, and *plugin-dir* options
+preceeding it,
 including the default built-in plugin directory. You can still add
-*plugin-dir* and *plugin* options following this and they will have the
-normal effect.
+*plugin-dir*, *plugin*, and *important-plugin* options following this
+and they will have the normal effect.
 
  **disable-plugin**=*PLUGIN*
 If *PLUGIN* contains a /, plugins with the same path as *PLUGIN* will
@@ -451,6 +452,17 @@ be loaded at startup, whatever directory it is in.  This option is useful for
 disabling a single plugin inside a directory.  You can still explicitly
 load plugins which have been disabled, using lightning-plugin(7) `start`.
 
+ **important-plugin**=*PLUGIN*
+Speciy a plugin to run as part of C-lightning.
+This can be specified multiple times to add multiple plugins.
+Plugins specified via this option are considered so important, that if the
+plugin stops for any reason (including via lightning-plugin(7) `stop`),
+C-lightning will also stop running.
+This way, you can monitor crashes of important plugins by simply monitoring
+if C-lightning terminates.
+Built-in plugins, which are installed with lightningd(8), are automatically
+considered important.
+
 BUGS
 ----
 

lightningd/Makefile

@@ -137,6 +137,9 @@ LIGHTNINGD_HEADERS = $(LIGHTNINGD_HEADERS_NOGEN) $(LIGHTNINGD_HEADERS_GEN) $(WAL
 
 $(LIGHTNINGD_OBJS): $(LIGHTNINGD_HEADERS)
 
+# Only the plugin component needs to depend on this header.
+lightningd/plugin.o : gen_list_of_builtin_plugins.h
+
 lightningd/gen_channel_state_names.h: lightningd/channel_state.h ccan/ccan/cdump/tools/cdump-enumstr
 	ccan/ccan/cdump/tools/cdump-enumstr lightningd/channel_state.h > $@
 

lightningd/lightningd.c

@@ -281,6 +281,11 @@ static struct lightningd *new_lightningd(const tal_t *ctx)
 	 */
 	ld->rpc_filemode = 0600;
 
+	/*~ This is the exit code to use on exit.
+	 * Set to NULL meaning we are not interested in exiting yet.
+	 */
+	ld->exit_code = NULL;
+
 	return ld;
 }
 
@@ -469,9 +474,9 @@ static const char *find_my_pkglibexec_path(struct lightningd *ld,
 
 	/*~ The plugin dir is in ../libexec/c-lightning/plugins, which (unlike
 	 * those given on the command line) does not need to exist. */
-	add_plugin_dir(ld->plugins,
-		       path_join(tmpctx, pkglibexecdir, "plugins"),
-		       true);
+	plugins_set_builtin_plugins_dir(ld->plugins,
+					path_join(tmpctx,
+						  pkglibexecdir, "plugins"));
 
 	/*~ Sometimes take() can be more efficient, since the routine can
 	 * manipulate the string in place.  This is the case here. */
@@ -484,10 +489,11 @@ static const char *find_daemon_dir(struct lightningd *ld, const char *argv0)
 	const char *my_path = find_my_directory(ld, argv0);
 	/* If we're running in-tree, all the subdaemons are with lightningd. */
 	if (has_all_subdaemons(my_path)) {
-		/* In this case, look in ../plugins */
-		add_plugin_dir(ld->plugins,
-			       path_join(tmpctx, my_path, "../plugins"),
-			       true);
+		/* In this case, look for built-in plugins in ../plugins */
+		plugins_set_builtin_plugins_dir(ld->plugins,
+						path_join(tmpctx,
+							  my_path,
+							  "../plugins"));
 		return my_path;
 	}
 
@@ -751,6 +757,14 @@ static void hsm_ecdh_failed(enum status_failreason fail,
 	fatal("hsm failure: %s", fmt);
 }
 
+/*~ This signals to the mainloop that some part wants to cleanly exit now.  */
+void lightningd_exit(struct lightningd *ld, int exit_code)
+{
+	ld->exit_code = tal(ld, int);
+	*ld->exit_code = exit_code;
+	io_break(ld);
+}
+
 int main(int argc, char *argv[])
 {
 	struct lightningd *ld;
@@ -763,6 +777,8 @@ int main(int argc, char *argv[])
 	struct ext_key *bip32_base;
 	struct rlimit nofile = {1024, 1024};
 
+	int exit_code = 0;
+
 	/*~ Make sure that we limit ourselves to something reasonable. Modesty
 	 *  is a virtue. */
 	setrlimit(RLIMIT_NOFILE, &nofile);
@@ -1002,10 +1018,17 @@ int main(int argc, char *argv[])
 	assert(io_loop_ret == ld);
 	ld->state = LD_STATE_SHUTDOWN;
 
-	/* Keep this fd around, to write final response at the end. */
-	stop_fd = io_conn_fd(ld->stop_conn);
-	io_close_taken_fd(ld->stop_conn);
-	stop_response = tal_steal(NULL, ld->stop_response);
+	/* Were we exited via `lightningd_exit`?  */
+	if (ld->exit_code) {
+		exit_code = *ld->exit_code;
+		stop_fd = -1;
+		stop_response = NULL;
+	} else {
+		/* Keep this fd around, to write final response at the end. */
+		stop_fd = io_conn_fd(ld->stop_conn);
+		io_close_taken_fd(ld->stop_conn);
+		stop_response = tal_steal(NULL, ld->stop_response);
+	}
 
 	shutdown_subdaemons(ld);
 
@@ -1040,11 +1063,13 @@ int main(int argc, char *argv[])
 
 	daemon_shutdown();
 
-	/* Finally, send response to shutdown command */
-	write_all(stop_fd, stop_response, strlen(stop_response));
-	close(stop_fd);
-	tal_free(stop_response);
+	/* Finally, send response to shutdown command if appropriate.  */
+	if (stop_fd >= 0) {
+		write_all(stop_fd, stop_response, strlen(stop_response));
+		close(stop_fd);
+		tal_free(stop_response);
+	}
 
 	/*~ Farewell.  Next stop: hsmd/hsmd.c. */
-	return 0;
+	return exit_code;
 }

lightningd/lightningd.h

@@ -271,6 +271,9 @@ struct lightningd {
 	/* Total number of coin moves we've seen, since
 	 * coin move tracking was cool */
 	s64 coin_moves_count;
+
+	/* If non-NULL, contains the exit code to use.  */
+	int *exit_code;
 };
 
 /* Turning this on allows a tal allocation to return NULL, rather than aborting.
@@ -289,4 +292,11 @@ void test_subdaemons(const struct lightningd *ld);
 /* Notify lightningd about new blocks. */
 void notify_new_block(struct lightningd *ld, u32 block_height);
 
+/* Signal a clean exit from lightningd.
+ * NOTE! This function **returns**.
+ * This just causes the main loop to exit, so you have to return
+ * all the way to the main loop for `lightningd` to exit.
+ */
+void lightningd_exit(struct lightningd *ld, int exit_code);
+
 #endif /* LIGHTNING_LIGHTNINGD_LIGHTNINGD_H */

lightningd/options.c

@@ -348,7 +348,7 @@ static char *opt_add_plugin(const char *arg, struct lightningd *ld)
 		log_info(ld->log, "%s: disabled via disable-plugin", arg);
 		return NULL;
 	}
-	plugin_register(ld->plugins, arg, NULL);
+	plugin_register(ld->plugins, arg, NULL, false);
 	return NULL;
 }
 
@@ -369,6 +369,16 @@ static char *opt_clear_plugins(struct lightningd *ld)
 	return NULL;
 }
 
+static char *opt_important_plugin(const char *arg, struct lightningd *ld)
+{
+	if (plugin_blacklisted(ld->plugins, arg)) {
+		log_info(ld->log, "%s: disabled via disable-plugin", arg);
+		return NULL;
+	}
+	plugin_register(ld->plugins, arg, NULL, true);
+	return NULL;
+}
+
 /* Prompt the user to enter a password, from which will be derived the key used
  * for `hsm_secret` encryption.
  * The algorithm used to derive the key is Argon2(id), to which libsodium
@@ -556,6 +566,10 @@ static void dev_register_opts(struct lightningd *ld)
 	opt_register_noarg("--dev-no-version-checks", opt_set_bool,
 			   &ld->dev_no_version_checks,
 			   "Skip calling subdaemons with --version on startup");
+	opt_register_early_noarg("--dev-builtin-plugins-unimportant",
+				 opt_set_bool,
+				 &ld->plugins->dev_builtin_plugins_unimportant,
+				 "Make builtin plugins unimportant so you can plugin stop them.");
 }
 #endif /* DEVELOPER */
 
@@ -771,6 +785,10 @@ static void register_opts(struct lightningd *ld)
 			       NULL, ld,
 			       "Disable a particular plugin by filename/name");
 
+	opt_register_early_arg("--important-plugin", opt_important_plugin,
+			       NULL, ld,
+			       "Add an important plugin to be run (can be used multiple times). Die if the plugin dies.");
+
 	/* Early, as it suppresses DNS lookups from cmdline too. */
 	opt_register_early_arg("--always-use-proxy",
 			       opt_set_bool_arg, opt_show_bool,
@@ -1278,6 +1296,9 @@ static void add_config(struct lightningd *ld,
 			json_add_opt_log_levels(response, ld->log);
 		} else if (opt->cb_arg == (void *)opt_disable_plugin) {
 			json_add_opt_disable_plugins(response, ld->plugins);
+		} else if (opt->cb_arg == (void *)opt_important_plugin) {
+			/* Do nothing, this is already handled by
+			 * opt_add_plugin.  */
 		} else if (opt->cb_arg == (void *)opt_add_plugin_dir
 			   || opt->cb_arg == (void *)plugin_opt_set
 			   || opt->cb_arg == (void *)plugin_opt_flag_set) {