in_node_exporter_metrics: add netstat linux collector

Extend node_exporter_metrics by exposing netstat metrics by parsing /proc/net/snmp data and
aligning the output with Prometheus node_exporter conventions.

Example parsed values from a live system:

  node_netstat_Tcp_ActiveOpens = 26581
  node_netstat_Tcp_PassiveOpens = 129
  node_netstat_Tcp_RetransSegs = 9254
  node_netstat_Tcp_CurrEstab = 6
  node_netstat_Udp_InDatagrams = 1292553
  node_netstat_Udp_OutDatagrams = 1601161
  node_netstat_Udp_NoPorts = 2047
  node_netstat_Udp_InErrors = 0

Signed-off-by: Eduardo Silva <[email protected]>

Author: edsiper

plugins/in_node_exporter_metrics/CMakeLists.txt

@@ -7,6 +7,7 @@ set(src
   ne_stat.c
   ne_vmstat.c
   ne_netdev.c
+  ne_netstat.c
   ne_sockstat.c
   ne_time.c
   ne_loadavg.c

plugins/in_node_exporter_metrics/ne.c

@@ -39,6 +39,7 @@
 #include "ne_loadavg.h"
 #include "ne_vmstat.h"
 #include "ne_netdev.h"
+#include "ne_netstat.h"
 #include "ne_sockstat.h"
 #include "ne_textfile.h"
 #include "ne_systemd.h"
@@ -194,6 +195,7 @@ static int in_ne_init(struct flb_input_instance *in,
     mk_list_add(&loadavg_collector._head, &ctx->collectors);
     mk_list_add(&vmstat_collector._head, &ctx->collectors);
     mk_list_add(&netdev_collector._head, &ctx->collectors);
+    mk_list_add(&netstat_collector._head, &ctx->collectors);
     mk_list_add(&sockstat_collector._head, &ctx->collectors);
     mk_list_add(&filefd_collector._head, &ctx->collectors);
     mk_list_add(&textfile_collector._head, &ctx->collectors);
@@ -389,6 +391,12 @@ static struct flb_config_map config_map[] = {
      "scrape interval to collect netdev metrics from the node."
     },
 
+    {
+     FLB_CONFIG_MAP_TIME, "collector.netstat.scrape_interval", "0",
+     0, FLB_FALSE, 0,
+     "scrape interval to collect netstat metrics from the node."
+    },
+
     {
      FLB_CONFIG_MAP_TIME, "collector.sockstat.scrape_interval", "0",
      0, FLB_FALSE, 0,

plugins/in_node_exporter_metrics/ne.h

@@ -33,7 +33,7 @@
 /* Default enabled metrics */
 
 #ifdef __linux__
-#define NE_DEFAULT_ENABLED_METRICS "cpu,cpufreq,meminfo,diskstats,filesystem,uname,stat,time,loadavg,vmstat,netdev,sockstat,filefd,systemd,nvme,thermal_zone,hwmon"
+#define NE_DEFAULT_ENABLED_METRICS "cpu,cpufreq,meminfo,diskstats,filesystem,uname,stat,time,loadavg,vmstat,netdev,netstat,sockstat,filefd,systemd,nvme,thermal_zone,hwmon"
 #elif __APPLE__
 #define NE_DEFAULT_ENABLED_METRICS "cpu,loadavg,meminfo,diskstats,uname,netdev"
 #endif
@@ -163,6 +163,16 @@ struct flb_ne {
     struct cmt_gauge *sockstat_FRAG6_inuse;
     struct cmt_gauge *sockstat_FRAG6_memory;
 
+    /* netstat_linux */
+    struct cmt_gauge   *netstat_Tcp_CurrEstab;
+    struct cmt_counter *netstat_Tcp_ActiveOpens;
+    struct cmt_counter *netstat_Tcp_PassiveOpens;
+    struct cmt_counter *netstat_Tcp_RetransSegs;
+    struct cmt_counter *netstat_Udp_InDatagrams;
+    struct cmt_counter *netstat_Udp_InErrors;
+    struct cmt_counter *netstat_Udp_OutDatagrams;
+    struct cmt_counter *netstat_Udp_NoPorts;
+
     /* time */
     struct cmt_gauge *time;
 

plugins/in_node_exporter_metrics/ne_netstat.c

@@ -0,0 +1,33 @@
+/* -*- Mode: C; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
+
+/*  Fluent Bit
+ *  ==========
+ *  Copyright (C) 2015-2025 The Fluent Bit Authors
+ *
+ *  Licensed under the Apache License, Version 2.0 (the "License");
+ *  you may not use this file except in compliance with the License.
+ *  You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ *  Unless required by applicable law or agreed to in writing, software
+ *  distributed under the License is distributed on an "AS IS" BASIS,
+ *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ *  See the License for the specific language governing permissions and
+ *  limitations under the License.
+ */
+
+#ifdef __linux__
+#include "ne_netstat_linux.c"
+#else
+
+#include "ne.h"
+
+struct flb_ne_collector netstat_collector = {
+    .name = "netstat",
+    .cb_init = NULL,
+    .cb_update = NULL,
+    .cb_exit = NULL
+};
+
+#endif

plugins/in_node_exporter_metrics/ne_netstat.h

@@ -0,0 +1,27 @@
+/* -*- Mode: C; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
+
+/*  Fluent Bit
+ *  ==========
+ *  Copyright (C) 2015-2025 The Fluent Bit Authors
+ *
+ *  Licensed under the Apache License, Version 2.0 (the "License");
+ *  you may not use this file except in compliance with the License.
+ *  You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ *  Unless required by applicable law or agreed to in writing, software
+ *  distributed under the License is distributed on an "AS IS" BASIS,
+ *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ *  See the License for the specific language governing permissions and
+ *  limitations under the License.
+ */
+
+#ifndef FLB_IN_NE_NETSTAT_H
+#define FLB_IN_NE_NETSTAT_H
+
+#include "ne.h"
+
+extern struct flb_ne_collector netstat_collector;
+
+#endif