[metrics] Add a basic CLI

systemd-report will list all the metrics.

Author: YapingLi04

meson.build

@@ -2398,6 +2398,7 @@ subdir('src/random-seed')
 subdir('src/rc-local-generator')
 subdir('src/remount-fs')
 subdir('src/repart')
+subdir('src/report')
 subdir('src/reply-password')
 subdir('src/resolve')
 subdir('src/rfkill')

src/report/meson.build

@@ -0,0 +1,9 @@
+# SPDX-License-Identifier: LGPL-2.1-or-later
+
+executables += [
+        executable_template + {
+                'name' : 'systemd-report',
+                'public' : true,
+                'sources' : files('report.c'),
+        },
+]

src/report/report.c

@@ -0,0 +1,233 @@
+/* SPDX-License-Identifier: LGPL-2.1-or-later */
+
+#include <getopt.h>
+
+#include "sd-event.h"
+#include "sd-varlink.h"
+
+#include "alloc-util.h"
+#include "ansi-color.h"
+#include "build.h"
+#include "dirent-util.h"
+#include "fd-util.h"
+#include "log.h"
+#include "main-func.h"
+#include "pretty-print.h"
+#include "string-util.h"
+#include "time-util.h"
+
+#define RUN_SYSTEMD_METRICS_PATH "/run/systemd/metrics/"
+#define MAX_CONCURRENT_METRICS_SOCKETS 20
+#define TIMEOUT_USEC (30 * USEC_PER_SEC) /* 30 seconds */
+
+typedef struct Context {
+        int n_open_connections;
+} Context;
+
+static int metrics_on_query_reply(
+                sd_varlink *link,
+                sd_json_variant *parameters,
+                const char *error_id,
+                sd_varlink_reply_flags_t flags,
+                void *userdata) {
+        assert(link);
+
+        Context *context = ASSERT_PTR(userdata);
+
+        if (error_id) {
+                if (streq(error_id, SD_VARLINK_ERROR_DISCONNECTED))
+                        log_info("Varlink disconnected");
+                else if (streq(error_id, SD_VARLINK_ERROR_TIMEOUT))
+                        log_info("Varlink timed out");
+                else
+                        log_error("Varlink error: %s", error_id);
+
+                goto finish;
+        }
+
+        sd_json_variant_dump(
+                        parameters,
+                        SD_JSON_FORMAT_PRETTY_AUTO | SD_JSON_FORMAT_COLOR_AUTO | SD_JSON_FORMAT_FLUSH,
+                        stdout,
+                        NULL);
+
+finish:
+        if (!FLAGS_SET(flags, SD_VARLINK_REPLY_CONTINUES)) {
+                assert(context->n_open_connections > 0);
+                context->n_open_connections--;
+
+                if (context->n_open_connections == 0)
+                        (void) sd_event_exit(ASSERT_PTR(sd_varlink_get_event(link)), EXIT_SUCCESS);
+        }
+
+        return 0;
+}
+
+static int metrics_call(const char *path, sd_event *event, sd_varlink **ret, Context *context) {
+        _cleanup_(sd_varlink_unrefp) sd_varlink *vl = NULL;
+        int r;
+
+        assert(path);
+        assert(event);
+        assert(ret);
+        assert(context);
+
+        r = sd_varlink_connect_address(&vl, path);
+        if (r < 0)
+                return log_debug_errno(r, "Unable to connect to %s: %m", path);
+
+        (void) sd_varlink_set_userdata(vl, context);
+
+        r = sd_varlink_set_relative_timeout(vl, TIMEOUT_USEC);
+        if (r < 0)
+                return log_error_errno(r, "Failed to set varlink timeout: %m");
+
+        r = sd_varlink_attach_event(vl, event, SD_EVENT_PRIORITY_NORMAL);
+        if (r < 0)
+                return log_debug_errno(r, "Failed to attach varlink connection to event loop: %m");
+
+        r = sd_varlink_bind_reply(vl, metrics_on_query_reply);
+        if (r < 0)
+                return log_debug_errno(r, "Failed to bind reply callback: %m");
+
+        r = sd_varlink_observe(vl, "io.systemd.Metrics.List", /* parameters= */ NULL);
+        if (r < 0)
+                return log_debug_errno(r, "Failed to issue io.systemd.Metrics.List call: %m");
+
+        *ret = TAKE_PTR(vl);
+
+        return 0;
+}
+
+static void sd_varlink_unref_many(sd_varlink **array, size_t n) {
+        assert(array);
+
+        FOREACH_ARRAY(v, array, n)
+        sd_varlink_unref(*v);
+
+        free(array);
+}
+
+static int metrics_query(void) {
+        _cleanup_closedir_ DIR *d = NULL;
+        _cleanup_(sd_event_unrefp) sd_event *event = NULL;
+        int r;
+
+        d = opendir(RUN_SYSTEMD_METRICS_PATH);
+        if (!d) {
+                if (errno == ENOENT)
+                        return 0;
+
+                return log_error_errno(errno, "Failed to open directory %s: %m", RUN_SYSTEMD_METRICS_PATH);
+        }
+
+        r = sd_event_default(&event);
+        if (r < 0)
+                return log_error_errno(r, "Failed to get event loop: %m");
+
+        r = sd_event_set_signal_exit(event, true);
+        if (r < 0)
+                return log_error_errno(r, "Failed to enable exit on SIGINT/SIGTERM: %m");
+
+        size_t n_varlinks = MAX_CONCURRENT_METRICS_SOCKETS;
+        sd_varlink **varlinks = new0(sd_varlink *, n_varlinks);
+        if (!varlinks)
+                return log_error_errno(ENOMEM, "Failed to allocate varlinks array: %m");
+
+        CLEANUP_ARRAY(varlinks, n_varlinks, sd_varlink_unref_many);
+
+        Context context = {};
+
+        FOREACH_DIRENT(de, d, return -errno) {
+                _cleanup_free_ char *p = NULL;
+
+                if (!IN_SET(de->d_type, DT_SOCK, DT_UNKNOWN))
+                        continue;
+
+                p = path_join(RUN_SYSTEMD_METRICS_PATH, de->d_name);
+                if (!p)
+                        return log_error_errno(ENOMEM, "Failed to allocate path: %m");
+
+                r = metrics_call(p, event, &varlinks[context.n_open_connections], &context);
+                if (r < 0) {
+                        log_error_errno(r, "Failed to connect to %s: %m", p);
+                        continue;
+                }
+
+                if (++context.n_open_connections >= MAX_CONCURRENT_METRICS_SOCKETS) {
+                        log_warning("Too many concurrent metrics sockets, stop iterating");
+                        break;
+                }
+        }
+
+        r = sd_event_loop(event);
+        if (r < 0)
+                return log_error_errno(r, "Failed to run event loop: %m");
+
+        return 0;
+}
+
+static int help(void) {
+        printf("%s [OPTIONS...] \n\n"
+               "%sPrint metrics for all system components.%s\n\n"
+               "  -h --help             Show this help\n"
+               "     --version          Show package version\n",
+               program_invocation_short_name,
+               ansi_highlight(),
+               ansi_normal());
+
+        return 0;
+}
+
+static int parse_argv(int argc, char *argv[]) {
+        enum { ARG_VERSION = 0x100 };
+
+        static const struct option options[] = {
+                { "help", no_argument, NULL, 'h' },
+                { "version", no_argument, NULL, ARG_VERSION },
+                {}
+        };
+
+        int c;
+
+        assert(argc >= 0);
+        assert(argv);
+
+        while ((c = getopt_long(argc, argv, "hp", options, NULL)) >= 0)
+                switch (c) {
+                case 'h':
+                        return help();
+                case ARG_VERSION:
+                        return version();
+                case '?':
+                        return -EINVAL;
+                default:
+                        assert_not_reached();
+                }
+
+        if (optind < argc)
+                return log_error_errno(
+                                SYNTHETIC_ERRNO(EINVAL),
+                                "%s takes no arguments.",
+                                program_invocation_short_name);
+
+        return 1;
+}
+
+static int run(int argc, char *argv[]) {
+        int r;
+
+        log_setup();
+
+        r = parse_argv(argc, argv);
+        if (r <= 0)
+                return r;
+
+        r = metrics_query();
+        if (r < 0)
+                return r;
+
+        return 0;
+}
+
+DEFINE_MAIN_FUNCTION_WITH_POSITIVE_FAILURE(run);

test/units/TEST-74-AUX-UTILS.varlinkctl.sh

@@ -226,3 +226,6 @@ systemd-run --wait --pipe --user --machine testuser@ \
 # test io.systemd.Unit in user manager
 systemd-run --wait --pipe --user --machine testuser@ \
         varlinkctl --more call "/run/user/$testuser_uid/systemd/io.systemd.Manager" io.systemd.Unit.List '{}'
+
+# test report
+systemd-report