Added health check

README.md

@@ -39,4 +39,11 @@ curl -H "Authorization: Bearer $API_TOKEN" \
      -i https://tesla-http-api.example.com/api/1/vehicles/{VIN}/command/flash_lights
 ```
 
-You can find all API endpoints in [Tesla's Fleet API documentation](https://developer.tesla.com/docs/fleet-api/endpoints/vehicle-commands).
+You can find all API endpoints in [Tesla's Fleet API documentation](https://developer.tesla.com/docs/fleet-api/endpoints/vehicle-commands).
+
+### Health check
+
+```bash
+curl -X GET \
+     -i https://tesla-http-api.example.com/health
+```

cmd/tesla-http-api/main.go

@@ -6,6 +6,7 @@ import (
 	"net/http"
 	"os"
 	"strconv"
+	"strings"
 	"time"
 
 	"github.com/L480/tesla-http-api/internal/logger"
@@ -30,21 +31,36 @@ var (
 	apiToken        string
 )
 
-func middleware(next http.Handler, teslaAccessToken string) http.Handler {
+func router(next http.Handler, teslaAccessToken string) http.Handler {
 	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
-		if apiTokenEnabled {
-			token := r.Header.Get("Authorization")
-			if token != apiToken {
-				logger.Info("Request to %s from %s \033[31m(invalid token)\033[0m", r.URL.Path, r.Header.Get("X-Forwarded-For"))
-				http.Error(w, http.StatusText(403), http.StatusForbidden)
+		path := strings.Split(r.URL.Path, "/")[1]
+		switch path {
+		case "health":
+			if tesla.Healthy {
+				http.Error(w, http.StatusText(200), http.StatusOK)
+				return
+			} else {
+				http.Error(w, http.StatusText(502), http.StatusBadGateway)
 				return
 			}
-			r.Header.Del("Authorization")
-		}
+		case "api":
+			if apiTokenEnabled {
+				token := r.Header.Get("Authorization")
+				if token != apiToken {
+					logger.Info("Request to %s from %s\033[31m(invalid token)\033[0m", r.URL.Path, r.Header.Get("X-Forwarded-For"))
+					http.Error(w, http.StatusText(403), http.StatusForbidden)
+					return
+				}
+				r.Header.Del("Authorization")
+			}
 
-		r.Header.Add("Authorization", "Bearer "+teslaAccessToken)
-		logger.Info("Request to %s from %s", r.URL.Path, r.Header.Get("X-Forwarded-For"))
-		next.ServeHTTP(w, r)
+			r.Header.Add("Authorization", "Bearer "+teslaAccessToken)
+			logger.Info("Request to %s from %s", r.URL.Path, r.Header.Get("X-Forwarded-For"))
+			next.ServeHTTP(w, r)
+		default:
+			http.Error(w, http.StatusText(404), http.StatusNotFound)
+			return
+		}
 	})
 }
 
@@ -58,7 +74,7 @@ func main() {
 	}
 
 	if !apiTokenEnabled {
-		logger.Warning("\033[33m%s IS SET TO FALSE. YOUR API IS UNPROTECTED AND CAN BE USED WITHOUT AUTHENTICATION. THIS IS NOT RECOMMENDED.\033[0m", EnvApiTokenEnabled)
+		logger.Warning("\033[1m\033[33m%s IS SET TO FALSE. YOUR API IS UNPROTECTED AND CAN BE USED WITHOUT AUTHENTICATION. THIS IS NOT RECOMMENDED.\033[0m", EnvApiTokenEnabled)
 	}
 
 	go tesla.RefreshToken(config)
@@ -79,7 +95,7 @@ func main() {
 
 	accessToken, err := os.ReadFile(config.AccessTokenFile)
 	logger.Info("Listening on %s", addr)
-	logger.Error("Server stopped: %s", http.ListenAndServe(addr, middleware(p, string(accessToken))))
+	logger.Error("Server stopped: %s", http.ListenAndServe(addr, router(p, string(accessToken))))
 }
 
 func readFromEnvironment() error {

internal/tesla/auth.go

@@ -20,27 +20,35 @@ type Config struct {
 	RefreshToken     string
 }
 
+var (
+	Healthy bool
+)
+
 func RefreshToken(c Config) {
 	tokenTimer := time.NewTimer(0)
 	refreshInterval := 6 * time.Hour
 	retryInterval := 5 * time.Minute
 	var latestRefreshToken string
+
 	type response struct {
 		AccessToken  string `json:"access_token"`
 		RefreshToken string `json:"refresh_token"`
 		IDToken      string `json:"id_token"`
 		ExpiresIn    int    `json:"expires_in"`
 		TokenType    string `json:"token_type"`
 	}
+
 	for {
 		<-tokenTimer.C
 		logger.Info("Refreshing access token ...")
 		file, err := os.ReadFile(c.RefreshTokenFile)
+
 		if err != nil {
 			latestRefreshToken = c.RefreshToken
 		} else {
 			latestRefreshToken = string(file)
 		}
+
 		form := url.Values{}
 		form.Add("grant_type", "refresh_token")
 		form.Add("client_id", c.ClientId)
@@ -52,40 +60,52 @@ func RefreshToken(c Config) {
 			Body:               form.Encode(),
 			InsecureSkipVerify: false,
 		}
+
 		resp, err := request.Connect(tokenEndpoint)
 		if err != nil {
+			Healthy = false
 			logger.Error("Failed to connect to token endpoint: %s", err)
 			tokenTimer.Reset(retryInterval)
 			continue
 		}
+
 		body, err := io.ReadAll(resp.Body)
 		resp.Body.Close()
 		if err != nil {
+			Healthy = false
 			logger.Error("Failed to retrieve response body: %s", err)
 			tokenTimer.Reset(retryInterval)
 			continue
 		}
+
 		if resp.StatusCode == 200 {
+			Healthy = true
 			logger.Info("Access token refresh successful")
 			logger.Info("Next access token refresh scheduled in %s hours", strconv.FormatFloat(refreshInterval.Hours(), 'g', 2, 64))
 			tokenTimer.Reset(refreshInterval)
 		} else {
-			logger.Error("Refresh failed: %s.", string(body))
+			Healthy = false
+			logger.Error("Refresh failed: %s", string(body))
+			logger.Info("Retrying access token refresh in %s minutes", strconv.FormatFloat(retryInterval.Minutes(), 'g', 2, 64))
 			tokenTimer.Reset(retryInterval)
 			continue
 		}
+
 		var jsonData response
 		json.Unmarshal(body, &jsonData)
 		accessTokenFile, err := os.Create(c.AccessTokenFile)
 		if err != nil {
+			Healthy = false
 			logger.Error("Failed to save access token: %s", err)
 			tokenTimer.Reset(retryInterval)
 			continue
 		}
+
 		accessTokenFile.WriteString(jsonData.AccessToken)
 		accessTokenFile.Close()
 		refreshTokenFile, err := os.Create(c.RefreshTokenFile)
 		if err != nil {
+			Healthy = false
 			logger.Error("Failed to save refresh token: %s", err)
 			tokenTimer.Reset(retryInterval)
 			continue