From 9dcc00900e45baf2c97e6af676e55cc2a347a247 Mon Sep 17 00:00:00 2001
From: Quentin McGaw <quentin.mcgaw@gmail.com>
Date: Mon, 31 Aug 2020 01:57:45 +0000
Subject: [PATCH] Healthcheck moved to HTTP control server

---
 internal/cli/cli.go       | 20 +++++++++++++-------
 internal/server/health.go | 27 +++++++++++++++++++++++++++
 internal/server/server.go |  5 +++++
 3 files changed, 45 insertions(+), 7 deletions(-)
 create mode 100644 internal/server/health.go

diff --git a/internal/cli/cli.go b/internal/cli/cli.go
index d1354f1f..ada447b6 100644
--- a/internal/cli/cli.go
+++ b/internal/cli/cli.go
@@ -3,12 +3,11 @@ package cli
 import (
 	"flag"
 	"fmt"
+	"io/ioutil"
 	"net/http"
 	"strings"
 	"time"
 
-	"net"
-
 	"github.com/qdm12/gluetun/internal/constants"
 	"github.com/qdm12/gluetun/internal/params"
 	"github.com/qdm12/gluetun/internal/provider"
@@ -40,13 +39,20 @@ func ClientKey(args []string) error {
 }
 
 func HealthCheck() error {
-	ips, err := net.LookupIP("github.com")
+	client := &http.Client{Timeout: time.Second}
+	response, err := client.Get("http://localhost:8000/health")
 	if err != nil {
-		return fmt.Errorf("cannot resolve github.com (%s)", err)
-	} else if len(ips) == 0 {
-		return fmt.Errorf("resolved no IP addresses for github.com")
+		return err
 	}
-	return nil
+	defer response.Body.Close()
+	if response.StatusCode == http.StatusOK {
+		return nil
+	}
+	b, err := ioutil.ReadAll(response.Body)
+	if err != nil {
+		return err
+	}
+	return fmt.Errorf("HTTP status code %s with message: %s", response.Status, string(b))
 }
 
 func OpenvpnConfig() error {
diff --git a/internal/server/health.go b/internal/server/health.go
new file mode 100644
index 00000000..5d7e0e73
--- /dev/null
+++ b/internal/server/health.go
@@ -0,0 +1,27 @@
+package server
+
+import (
+	"fmt"
+	"net/http"
+)
+
+func (s *server) handleHealth(w http.ResponseWriter) {
+	// TODO option to disable
+	// TODO use mullvad API if current provider is Mullvad
+	ips, err := s.lookupIP("github.com")
+	var errorMessage string
+	switch {
+	case err != nil:
+		errorMessage = fmt.Sprintf("cannot resolve github.com (%s)", err)
+	case len(ips) == 0:
+		errorMessage = "resolved no IP addresses for github.com"
+	default: // success
+		w.WriteHeader(http.StatusOK)
+		return
+	}
+	s.logger.Warn(errorMessage)
+	w.WriteHeader(http.StatusInternalServerError)
+	if _, err := w.Write([]byte(errorMessage)); err != nil {
+		s.logger.Warn(err)
+	}
+}
diff --git a/internal/server/server.go b/internal/server/server.go
index 6ef6f6a8..10ef8c4f 100644
--- a/internal/server/server.go
+++ b/internal/server/server.go
@@ -3,6 +3,7 @@ package server
 import (
 	"context"
 	"fmt"
+	"net"
 	"net/http"
 	"sync"
 	"time"
@@ -22,6 +23,7 @@ type server struct {
 	restartUnbound     func()
 	getOpenvpnSettings func() settings.OpenVPN
 	getPortForwarded   func() uint16
+	lookupIP           func(host string) ([]net.IP, error)
 }
 
 func New(address string, logger logging.Logger, restartOpenvpn, restartUnbound func(),
@@ -33,6 +35,7 @@ func New(address string, logger logging.Logger, restartOpenvpn, restartUnbound f
 		restartUnbound:     restartUnbound,
 		getOpenvpnSettings: getOpenvpnSettings,
 		getPortForwarded:   getPortForwarded,
+		lookupIP:           net.LookupIP,
 	}
 }
 
@@ -71,6 +74,8 @@ func (s *server) makeHandler() http.HandlerFunc {
 				s.handleGetPortForwarded(w)
 			case "/openvpn/settings":
 				s.handleGetOpenvpnSettings(w)
+			case "/health":
+				s.handleHealth(w)
 			default:
 				routeDoesNotExist(s.logger, w, r)
 			}