503 Service Unavailable

HTTP/1.1 503 Service Unavailable
Retry-After: 3600
Content-Type: application/json

{
  "error": "Service Unavailable",
  "message": "We are currently undergoing maintenance. Please try again in 1 hour."
}

let isMaintenanceMode = true;

app.use((req, res, next) => {
  if (isMaintenanceMode) {
    res.set("Retry-After", "3600"); // Retry after 1 hour
    return res.status(503).json({
      error: "Service Unavailable",
      message: "The server is currently under maintenance."
    });
  }
  next();
});

from fastapi import FastAPI, HTTPException
from fastapi.responses import JSONResponse

app = FastAPI()

@app.get("/")
def get_root():
    headers = {"Retry-After": "300"} # 5 minutes
    return JSONResponse(
        status_code=503,
        content={"message": "System is down for maintenance"},
        headers=headers
    )

package main

import "net/http"

func handler(w http.ResponseWriter, r *http.Request) {
	w.Header().Set("Retry-After", "120")
	http.Error(w, "Service Unavailable due to maintenance", http.StatusServiceUnavailable)
}

func main() {
	http.HandleFunc("/", handler)
	http.ListenAndServe(":8080", nil)
}

public class MaintenanceMiddleware
{
    private readonly RequestDelegate _next;
    private readonly bool _isMaintenance = true;

    public MaintenanceMiddleware(RequestDelegate next) => _next = next;

    public async Task Invoke(HttpContext context)
    {
        if (_isMaintenance)
        {
            context.Response.StatusCode = 503;
            context.Response.Headers.Add("Retry-After", "600");
            await context.Response.WriteAsync("Service Unavailable");
            return;
        }
        await _next(context);
    }
}