in_node_exporter_metrics: add new option 'path.rootfs' (backport v4.0)

conf/fluent-bit-metrics.conf

@@ -15,6 +15,8 @@
     name            node_exporter_metrics
     tag             node_metrics
     scrape_interval 2
+    # use host root path when running in containers
+    # path.rootfs     /host
 
 [OUTPUT]
     name            prometheus_exporter

docker_compose/node-exporter-dashboard/docker-compose.yml

@@ -4,14 +4,13 @@ services:
   fluentbit:
     image: fluent/fluent-bit:latest
     container_name: fluentbit
-    command: /fluent-bit/bin/fluent-bit -i node_exporter_metrics -p path.procfs=/host/proc -p path.sysfs=/host/sys -o prometheus_exporter -p "add_label=host fluentbit" -f 1
+    command: /fluent-bit/bin/fluent-bit -i node_exporter_metrics -p path.rootfs=/host -o prometheus_exporter -p "add_label=host fluentbit" -f 1
     ports:
       - 2021:2021
     networks:
       - exporter-network
     volumes:
-      - /proc:/host/proc
-      - /sys:/host/sys
+      - /:/host:ro
 
   grafana:
     image: grafana/grafana:latest

plugins/in_node_exporter_metrics/ne.c

@@ -441,6 +441,12 @@ static struct flb_config_map config_map[] = {
      "Specify file path or directory to collect textfile metrics from the node."
     },
 
+    {
+     FLB_CONFIG_MAP_STR, "path.rootfs", "/",
+     0, FLB_TRUE, offsetof(struct flb_ne, path_rootfs),
+     "rootfs mount point"
+    },
+
     {
      FLB_CONFIG_MAP_STR, "path.procfs", "/proc",
      0, FLB_TRUE, offsetof(struct flb_ne, path_procfs),

plugins/in_node_exporter_metrics/ne.h

@@ -48,6 +48,7 @@
 
 struct flb_ne {
     /* configuration */
+    flb_sds_t path_rootfs;
     flb_sds_t path_procfs;
     flb_sds_t path_sysfs;
     flb_sds_t path_textfile;

plugins/in_node_exporter_metrics/ne_config.c

@@ -24,6 +24,8 @@ struct flb_ne *flb_ne_config_create(struct flb_input_instance *ins,
                                     struct flb_config *config)
 {
     int ret;
+    int root_len;
+    flb_sds_t tmp;
     struct flb_ne *ctx;
 
     ctx = flb_calloc(1, sizeof(struct flb_ne));
@@ -41,6 +43,59 @@ struct flb_ne *flb_ne_config_create(struct flb_input_instance *ins,
     }
 
     /* mount points */
+    flb_plg_info(ins, "path.rootfs = %s", ctx->path_rootfs);
+
+    if (ctx->path_rootfs && strcmp(ctx->path_rootfs, "/") != 0) {
+        root_len = strlen(ctx->path_rootfs);
+        if (root_len > 1 && ctx->path_rootfs[root_len - 1] == '/') {
+            root_len--;
+        }
+
+        /* Compose procfs path */
+        tmp = flb_sds_create_size(1024);
+        if (tmp) {
+            if (ctx->path_procfs[0] == '/') {
+                tmp = flb_sds_printf(&tmp, "%.*s%s", root_len, ctx->path_rootfs, ctx->path_procfs);
+            }
+            else {
+                tmp = flb_sds_printf(&tmp, "%.*s/%s", root_len, ctx->path_rootfs, ctx->path_procfs);
+            }
+            if (tmp) {
+                ctx->path_procfs = tmp;
+            }
+        }
+
+        /* Compose sysfs path */
+        tmp = flb_sds_create_size(1024);
+        if (tmp) {
+            if (ctx->path_sysfs[0] == '/') {
+                tmp = flb_sds_printf(&tmp, "%.*s%s", root_len, ctx->path_rootfs, ctx->path_sysfs);
+            }
+            else {
+                tmp = flb_sds_printf(&tmp, "%.*s/%s", root_len, ctx->path_rootfs, ctx->path_sysfs);
+            }
+            if (tmp) {
+                ctx->path_sysfs = tmp;
+            }
+        }
+
+        /* Compose textfile path if any */
+        if (ctx->path_textfile) {
+            tmp = flb_sds_create_size(1024);
+            if (tmp) {
+                if (ctx->path_textfile[0] == '/') {
+                    tmp = flb_sds_printf(&tmp, "%.*s%s", root_len, ctx->path_rootfs, ctx->path_textfile);
+                }
+                else {
+                    tmp = flb_sds_printf(&tmp, "%.*s/%s", root_len, ctx->path_rootfs, ctx->path_textfile);
+                }
+                if (tmp) {
+                    ctx->path_textfile = tmp;
+                }
+            }
+        }
+    }
+
     flb_plg_info(ins, "path.procfs = %s", ctx->path_procfs);
     flb_plg_info(ins, "path.sysfs  = %s", ctx->path_sysfs);
 

plugins/in_node_exporter_metrics/ne_stat_linux.c

@@ -85,6 +85,7 @@ static int stat_update(struct flb_ne *ctx)
     mk_list_init(&list);
     ret = ne_utils_file_read_lines(ctx->path_procfs, "/stat", &list);
     if (ret == -1) {
+        flb_plg_error(ctx->ins, "failed to read %s/stat", ctx->path_procfs);
         return -1;
     }
 

plugins/in_node_exporter_metrics/ne_utils.c

@@ -196,9 +196,9 @@ int ne_utils_file_read_lines(const char *mount, const char *path, struct mk_list
 /*
  * Read a file and store the first line as a string.
  */
-int ne_utils_file_read_sds(const char *mount, 
-                           const char *path, 
-                           const char *join_a, 
+int ne_utils_file_read_sds(const char *mount,
+                           const char *path,
+                           const char *join_a,
                            const char *join_b,
                            flb_sds_t *str)
 {

plugins/in_node_exporter_metrics/ne_utils.h

@@ -35,8 +35,8 @@ int ne_utils_file_read_uint64(const char *mount,
 
 int ne_utils_file_read_sds(const char *mount,
                            const char *path,
-                           const char *join_a, 
-                           const char *join_b, 
+                           const char *join_a,
+                           const char *join_b,
                            flb_sds_t *str);
 
 int ne_utils_file_read_lines(const char *mount, const char *path, struct mk_list *list);