From d3c13b7bd6e4860ad6b135ae465dbd55c55644c0 Mon Sep 17 00:00:00 2001
From: belajarqywok <belajarqywok@gmail.com>
Date: Tue, 9 Jul 2024 00:35:00 +0700
Subject: [PATCH] feat: add node exporter proxy feature

---
 main.go                                 |  9 ++++
 proxy/node_exporter/exporter_handler.go | 60 +++++++++++++++++++++++++
 proxy/node_exporter/exporter_service.go | 41 +++++++++++++++++
 proxy/node_exporter/interfaces.go       | 11 +++++
 4 files changed, 121 insertions(+)
 create mode 100644 proxy/node_exporter/exporter_handler.go
 create mode 100644 proxy/node_exporter/exporter_service.go
 create mode 100644 proxy/node_exporter/interfaces.go

diff --git a/main.go b/main.go
index 5437582..76115df 100644
--- a/main.go
+++ b/main.go
@@ -8,9 +8,13 @@ import (
 
 	proxy "tebakaja_lb_proxy/proxy"
 
+	// Main Features
 	stock_proxy "tebakaja_lb_proxy/proxy/stock"
 	crypto_proxy "tebakaja_lb_proxy/proxy/crypto"
 	national_currency_proxy "tebakaja_lb_proxy/proxy/national_currency"
+
+	// Node Exporter
+	// exporter_proxy "tebakaja_lb_proxy/proxy/node_exporter"
 )
 
 func main() {
@@ -42,6 +46,11 @@ func main() {
 		national_currency_proxy.NationalCurrencyPredictionHandler(
 			&national_currency_proxy.NationalCurrencyServiceImpl{}))
 
+	// exporterGroup := proxyService.Group("/exporter")
+	// exporterGroup.Get("/metrics",
+	// 	exporter_proxy.ExporterMetricsHandler(
+	// 		&exporter_proxy.ExporterServiceImpl{}))
+
 	port := 7860
 	log.Fatal(proxyService.Listen(fmt.Sprintf("0.0.0.0:%d", port)))
 }
diff --git a/proxy/node_exporter/exporter_handler.go b/proxy/node_exporter/exporter_handler.go
new file mode 100644
index 0000000..5b39060
--- /dev/null
+++ b/proxy/node_exporter/exporter_handler.go
@@ -0,0 +1,60 @@
+package exporter
+
+import (
+	"log"
+	"sync"
+	"time"
+	"context"
+	"net/http"
+
+	"github.com/gofiber/fiber/v2"
+)
+
+
+/*
+ *  --- Node Exporter Metric Handler ---
+ */
+func ExporterMetricsHandler(service ExporterService) fiber.Handler {
+	return func(c *fiber.Ctx) error {
+		ctx, cancel := context.WithTimeout(c.Context(), 120 * time.Second)
+		defer cancel()
+
+		ch := make(chan string, 1)
+		var wg sync.WaitGroup
+		wg.Add(1)
+
+		go func() {
+			defer wg.Done()
+
+			apiResponse, err := service.ExporterMetricsService(ctx)
+			if err != nil {
+				log.Printf("[%s] %v", time.Now().Format("2006-01-02 15:04:05"), err)
+				ch <- apiResponse
+				return
+			}
+
+			ch <- apiResponse
+		}()
+
+		go func() {
+			wg.Wait()
+			close(ch)
+		}()
+
+		select {
+			case apiResponse, ok := <-ch:
+				if !ok {
+					return c.Status(http.StatusInternalServerError).JSON(fiber.Map{
+						"error": "Failed to get a response from the server",
+					})
+				}
+				return c.SendString(apiResponse)
+
+			case <-ctx.Done():
+				log.Printf("[%s] Timeout: %v", time.Now().Format("2006-01-02 15:04:05"), ctx.Err())
+				return c.Status(http.StatusRequestTimeout).JSON(fiber.Map{
+					"error": "Request timeout",
+				})
+		}
+	}
+}
diff --git a/proxy/node_exporter/exporter_service.go b/proxy/node_exporter/exporter_service.go
new file mode 100644
index 0000000..1b2ef71
--- /dev/null
+++ b/proxy/node_exporter/exporter_service.go
@@ -0,0 +1,41 @@
+package exporter
+
+import (
+	"context"
+	"fmt"
+	"io"
+	"net/http"
+)
+
+
+/*
+ *  --- Node Exporter Metric Service ---
+ */
+func (s *ExporterServiceImpl) ExporterMetricsService(ctx context.Context) (string, error) {
+	endpoint := fmt.Sprintf("%s/metrics", "http://localhost:9100")
+	req, err := http.NewRequestWithContext(ctx, "GET", endpoint, nil)
+	if err != nil {
+		return "", fmt.Errorf("failed to create request: %v", err)
+	}
+
+	resp, err := http.DefaultClient.Do(req)
+	if err != nil {
+		return "", fmt.Errorf("failed to perform request: %v", err)
+	}
+	defer resp.Body.Close()
+
+	if resp.StatusCode != http.StatusOK {
+		return "", fmt.Errorf("request failed with status code: %d", resp.StatusCode)
+	}
+
+	// Read the response body as plain text
+	body, err := io.ReadAll(resp.Body)
+	if err != nil {
+		return "", fmt.Errorf("failed to read response body: %v", err)
+	}
+
+	// Convert []byte to string
+	metricsResponse := string(body)
+
+	return metricsResponse, nil
+}
diff --git a/proxy/node_exporter/interfaces.go b/proxy/node_exporter/interfaces.go
new file mode 100644
index 0000000..46757e0
--- /dev/null
+++ b/proxy/node_exporter/interfaces.go
@@ -0,0 +1,11 @@
+package exporter
+
+import "context"
+
+type ExporterService interface {
+	ExporterMetricsService(ctx context.Context) (string, error)
+	// ExporterVersionInfoService(ctx context.Context) (string, error)
+	// ExporterHealthCheckService(ctx context.Context) (string, error)
+}
+
+type ExporterServiceImpl struct{}
\ No newline at end of file