samples: net: prometheus: Add support for network statistics

Add separate URL handling for network statistics.

Signed-off-by: Jukka Rissanen <jukka.rissanen@nordicsemi.no>

samples/net/prometheus/CMakeLists.txt

@@ -22,6 +22,7 @@ endif()
 
 
 target_sources(app PRIVATE src/main.c)
+target_sources_ifdef(CONFIG_NET_STATISTICS_VIA_PROMETHEUS app PRIVATE src/stats.c)
 
 set(gen_dir ${ZEPHYR_BINARY_DIR}/include/generated/)
 

samples/net/prometheus/prj.conf

@@ -84,3 +84,7 @@ CONFIG_NET_SOCKETS_LOG_LEVEL_DBG=n
 CONFIG_NET_HTTP_LOG_LEVEL_DBG=n
 CONFIG_NET_IPV6_LOG_LEVEL_DBG=n
 CONFIG_NET_IPV6_ND_LOG_LEVEL_DBG=n
+
+# Network statistics Prometheus support
+CONFIG_NET_STATISTICS_VIA_PROMETHEUS=y
+CONFIG_NET_STATISTICS=y

samples/net/prometheus/src/main.c

@@ -27,7 +27,9 @@
 #include <zephyr/logging/log.h>
 LOG_MODULE_REGISTER(main, LOG_LEVEL_DBG);
 
-struct {
+extern int init_stats(struct prometheus_counter *counter);
+
+struct app_context {
 
 	struct prometheus_collector *collector;
 
@@ -88,7 +90,7 @@ HTTP_RESOURCE_DEFINE(dyn_resource, test_http_service, "/metrics", &dyn_resource_
 #if defined(CONFIG_NET_SAMPLE_HTTPS_SERVICE)
 #include "certificate.h"
 
-static const sec_tag_t sec_tag_list_verify_none[] = {
+const sec_tag_t sec_tag_list_verify_none[] = {
 	HTTP_SERVER_CERTIFICATE_TAG,
 #if defined(CONFIG_MBEDTLS_KEY_EXCHANGE_PSK_ENABLED)
 	PSK_TAG,
@@ -160,6 +162,10 @@ int main(void)
 
 	prometheus_collector_register_metric(prom_context.collector, &prom_context.counter->base);
 
+#if defined(CONFIG_NET_STATISTICS_VIA_PROMETHEUS)
+	(void)init_stats(prom_context.counter);
+#endif
+
 	setup_tls();
 
 	http_server_start();

samples/net/prometheus/src/stats.c

@@ -0,0 +1,98 @@
+/*
+ * Copyright (c) 2024 Nordic Semiconductor
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+#include <zephyr/logging/log.h>
+LOG_MODULE_DECLARE(main, LOG_LEVEL_DBG);
+
+#include <zephyr/kernel.h>
+#include <zephyr/kernel.h>
+#include <zephyr/net/tls_credentials.h>
+#include <zephyr/net/http/server.h>
+#include <zephyr/net/http/service.h>
+#include <zephyr/net/net_if.h>
+#include <zephyr/net/net_ip.h>
+
+#include <zephyr/net/prometheus/formatter.h>
+#include <zephyr/net/prometheus/collector.h>
+#include <zephyr/net/prometheus/counter.h>
+#include <zephyr/net/prometheus/gauge.h>
+#include <zephyr/net/prometheus/histogram.h>
+#include <zephyr/net/prometheus/summary.h>
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+extern struct http_service_desc test_http_service;
+
+static struct prometheus_counter *http_request_counter;
+static struct prometheus_collector *stats_collector;
+static struct prometheus_collector_walk_context walk_ctx;
+
+static int stats_handler(struct http_client_ctx *client, enum http_data_status status,
+			 uint8_t *buffer, size_t len, struct http_response_ctx *response_ctx,
+			 void *user_data)
+{
+	int ret;
+	static uint8_t prom_buffer[1024];
+
+	if (status == HTTP_SERVER_DATA_FINAL) {
+
+		/* incrase counter per request */
+		prometheus_counter_inc(http_request_counter);
+
+		(void)memset(prom_buffer, 0, sizeof(prom_buffer));
+
+		ret = prometheus_collector_walk_metrics(user_data,
+							prom_buffer,
+							sizeof(prom_buffer));
+		if (ret < 0 && ret != -EAGAIN) {
+			LOG_ERR("Cannot format exposition data (%d)", ret);
+			return ret;
+		}
+
+		response_ctx->body = prom_buffer;
+		response_ctx->body_len = strlen(prom_buffer);
+
+		if (ret == 0) {
+			response_ctx->final_chunk = true;
+			ret = prometheus_collector_walk_init(&walk_ctx, stats_collector);
+			if (ret < 0) {
+				LOG_ERR("Cannot initialize walk context (%d)", ret);
+			}
+		}
+	}
+
+	return 0;
+}
+
+struct http_resource_detail_dynamic stats_resource_detail = {
+	.common = {
+			.type = HTTP_RESOURCE_TYPE_DYNAMIC,
+			.bitmask_of_supported_http_methods = BIT(HTTP_GET),
+			.content_type = "text/plain",
+	},
+	.cb = stats_handler,
+	.user_data = &walk_ctx,
+};
+
+HTTP_RESOURCE_DEFINE(stats_resource, test_http_service, "/statistics", &stats_resource_detail);
+
+int init_stats(struct prometheus_counter *counter)
+{
+	/* Use a collector from default network interface */
+	stats_collector = net_if_get_default()->collector;
+	if (stats_collector == NULL) {
+		LOG_ERR("Cannot get collector from default network interface");
+		return -EINVAL;
+	}
+
+	(void)prometheus_collector_walk_init(&walk_ctx, stats_collector);
+
+	http_request_counter = counter;
+
+	return 0;
+}