Issue in sending sensor data from ESP8266 to Ngrok tunnel

With a free ngrok account, I was able to generate a static HTTP domain. In my localhost a code is running to receive and decode the data from port 80. The localhost is mapped to the ngrok tunnel. Now, I have a few ESP8266 nodes which send data to this HTTP domain frequently. The data is sent to the domain with a POST REQUEST method. The response code arrived is 307 instead of 200. Can you please guide me where the error might be?

The program that runs on ESP8266 is given below:

#include <ESP8266WiFi.h>
#include <ESP8266HTTPClient.h>
#include <WiFiClient.h>

const char* ssid = "";
const char* password = "";

void setup() {
  Serial.begin(115200);
  WiFi.begin(ssid, password);

  while (WiFi.status() != WL_CONNECTED) {
    delay(1000);
    Serial.println("Connecting to WiFi...");
  }

  Serial.println("Connected to WiFi");
}

void loop() {
  if (WiFi.status() == WL_CONNECTED) {
    HTTPClient http;
    WiFiClient client;

    http.begin(client, "https://domain.ngrok-free.app");
    http.addHeader("Content-Type", "text/plain");

    String postMessage = "$A123";

    int httpResponseCode = http.POST(postMessage);

    if (httpResponseCode > 0) {
      String response = http.getString();
      Serial.println(httpResponseCode);
      Serial.println(response);
    } else {
      Serial.print("Error on sending POST: ");
      Serial.println(httpResponseCode);
    }

    http.end();
  } else {
    Serial.println("Error in WiFi connection");
  }

  delay(10000);  // Send a request every 10 seconds
}

In the localhost:

from flask import Flask, request

app = Flask(__name__)

@app.route('/', methods=['POST', 'GET'])
def home():
    if request.method == 'POST':
        data = request.data  # Get the data from the POST request
        print("Received data: ", data)
        return 'OK', 200  # Send a response back to the ESP8266
    else:
        return 'Hello, World!', 200  # Send a response for GET requests

if __name__ == '__main__':
    app.run(port=443)

inconshreveable / ngrok

Issue in sending sensor data from ESP8266 to Ngrok tunnel #945