feat: metrics_agent inicial (collect+format+push host metrics a VictoriaMetrics)

config.go

@@ -0,0 +1,65 @@
+package main
+
+import (
+	"encoding/json"
+	"os"
+	"strconv"
+)
+
+// Config holds the agent runtime configuration. It is read from an optional
+// JSON file and can be overridden by environment variables, which is handy for
+// systemd drop-ins and for deploying the same binary to many nodes.
+type Config struct {
+	Node        string `json:"node"`         // value of the "instance" label attached to every series
+	HubURL      string `json:"hub_url"`      // full ingest URL, e.g. https://metrics-…/api/v1/import/prometheus
+	User        string `json:"user"`         // basic-auth user (empty disables auth)
+	Pass        string `json:"pass"`         // basic-auth password
+	IntervalSec int    `json:"interval_sec"` // push period in seconds (default 15)
+}
+
+// defaultConfig returns the baseline configuration: the machine hostname as the
+// node name and a 15-second push interval.
+func defaultConfig() Config {
+	host, _ := os.Hostname()
+	return Config{Node: host, IntervalSec: 15}
+}
+
+// loadConfig reads the JSON file at path (when non-empty) and then applies
+// environment overrides. Recognised env vars: FLEET_NODE, FLEET_HUB_URL,
+// FLEET_USER, FLEET_PASS, FLEET_INTERVAL.
+func loadConfig(path string) (Config, error) {
+	cfg := defaultConfig()
+	if path != "" {
+		b, err := os.ReadFile(path)
+		if err != nil {
+			return cfg, err
+		}
+		if err := json.Unmarshal(b, &cfg); err != nil {
+			return cfg, err
+		}
+	}
+	if v := os.Getenv("FLEET_NODE"); v != "" {
+		cfg.Node = v
+	}
+	if v := os.Getenv("FLEET_HUB_URL"); v != "" {
+		cfg.HubURL = v
+	}
+	if v := os.Getenv("FLEET_USER"); v != "" {
+		cfg.User = v
+	}
+	if v := os.Getenv("FLEET_PASS"); v != "" {
+		cfg.Pass = v
+	}
+	if v := os.Getenv("FLEET_INTERVAL"); v != "" {
+		if n, err := strconv.Atoi(v); err == nil && n > 0 {
+			cfg.IntervalSec = n
+		}
+	}
+	if cfg.IntervalSec <= 0 {
+		cfg.IntervalSec = 15
+	}
+	if cfg.Node == "" {
+		cfg.Node, _ = os.Hostname()
+	}
+	return cfg, nil
+}