Initial cloud-services repo - gateway service + pkg modules

pkg/health/http.go

@@ -0,0 +1,56 @@
+package health
+
+import (
+	"context"
+	"errors"
+	"fmt"
+	"net/http"
+	"time"
+)
+
+const defaultRequestTimeout = 5 * time.Second
+
+// Config is the HTTP checker configuration settings container.
+type HTTPConfig struct {
+	// URL is the remote service health check URL.
+	URL string
+	// RequestTimeout is the duration that health check will try to consume published test message.
+	// If not set - 5 seconds
+	RequestTimeout time.Duration
+}
+
+// New creates new HTTP service health check that verifies the following:
+// - connection establishing
+// - getting response status from defined URL
+// - verifying that status code is less than 500
+func NewHTTPCheck(config HTTPConfig) CheckFunc {
+	if config.RequestTimeout == 0 {
+		config.RequestTimeout = defaultRequestTimeout
+	}
+
+	return func(ctx context.Context) error {
+		req, err := http.NewRequest(http.MethodGet, config.URL, nil)
+		if err != nil {
+			return fmt.Errorf("creating the request for the health check failed: %w", err)
+		}
+
+		ctx, cancel := context.WithTimeout(ctx, config.RequestTimeout)
+		defer cancel()
+
+		// Inform remote service to close the connection after the transaction is complete
+		req.Header.Set("Connection", "close")
+		req = req.WithContext(ctx)
+
+		res, err := http.DefaultClient.Do(req)
+		if err != nil {
+			return fmt.Errorf("making the request for the health check failed: %w", err)
+		}
+		defer res.Body.Close()
+
+		if res.StatusCode >= http.StatusInternalServerError {
+			return errors.New("remote service is not available at the moment")
+		}
+
+		return nil
+	}
+}