feat(infra): grupo fleet-metrics — collect_host_metrics, format_prom_exposition, push_prom_remote, push_loki_stream, collect_battery_metrics + tipo PromSample (gopsutil; Android-safe: sin exec/pidfd, procesos via /proc)

functions/infra/push_prom_remote.go

@@ -0,0 +1,60 @@
+package infra
+
+import (
+	"fmt"
+	"io"
+	"net/http"
+	"net/url"
+	"strings"
+	"time"
+)
+
+// PushPromRemote hace POST del body (texto en formato Prometheus exposition) al
+// endpoint dado, tipicamente el import de VictoriaMetrics
+// (".../api/v1/import/prometheus").
+//
+//   - Si user != "" usa Basic Auth con user/pass.
+//   - extraLabels se adjuntan como query params repetidos
+//     "extra_label=clave=valor" URL-encoded. VictoriaMetrics añade esas labels a
+//     TODAS las series del push (util para la label "instance").
+//   - Content-Type: text/plain.
+//   - http.Client con Timeout 10s y TLS verificado.
+//   - Exito = status 2xx (VictoriaMetrics devuelve 204). Si no-2xx, retorna error
+//     con el codigo y los primeros 200 bytes del cuerpo de respuesta.
+func PushPromRemote(endpoint string, user string, pass string, body string, extraLabels map[string]string) error {
+	u, err := url.Parse(endpoint)
+	if err != nil {
+		return fmt.Errorf("parse endpoint %q: %w", endpoint, err)
+	}
+
+	if len(extraLabels) > 0 {
+		q := u.Query()
+		for k, v := range extraLabels {
+			q.Add("extra_label", k+"="+v)
+		}
+		u.RawQuery = q.Encode()
+	}
+
+	req, err := http.NewRequest(http.MethodPost, u.String(), strings.NewReader(body))
+	if err != nil {
+		return fmt.Errorf("build request: %w", err)
+	}
+	req.Header.Set("Content-Type", "text/plain")
+	if user != "" {
+		req.SetBasicAuth(user, pass)
+	}
+
+	client := &http.Client{Timeout: 10 * time.Second}
+	resp, err := client.Do(req)
+	if err != nil {
+		return fmt.Errorf("push to %q: %w", endpoint, err)
+	}
+	defer resp.Body.Close()
+
+	if resp.StatusCode < 200 || resp.StatusCode >= 300 {
+		snippet, _ := io.ReadAll(io.LimitReader(resp.Body, 200))
+		return fmt.Errorf("push to %q failed: status %d: %s", endpoint, resp.StatusCode, string(snippet))
+	}
+
+	return nil
+}