Get the Domain or Host name and Port in Configure of Startup.cs

Question

I'm in need of help in getting the host/domain name and port of my application.

So far, here's my sample code in my Configure method inside the Startup.cs:

public void Configure(IApplicationBuilder app, IHostingEnvironment env)
{
    var url = ""; // something that will get the current host/domain and port of the running applicaiton.

    RecurringJob.AddOrUpdate<ISomething>(i=>i.SomethingToExecute(url), Cron.Daily);
}

Because I need to pass the url string to my SomethingToExecute method

public class Something : ISomething 
{
    public void SomethingToExecute(string url){
        ... 
        Debug.WriteLine(url)
    }
}

Maybe this will help you. https://stackoverflow.com/a/47051481/2251733 — Nilay Mehta, Mar 27 '19 at 03:55
I think this might be an [XY Problem](https://en.wikipedia.org/wiki/XY_problem). It might help if you edit your question to explain why you are trying to do this? There may be better solutions to your problem than the way you are trying to solve it. — Simply Ged, Mar 27 '19 at 06:52

score 7 · Accepted Answer · answered Mar 27 '19 at 06:38

7

According to this Github Issue and response from the ASP.NET Core team:

It's not possible. You need to read this information directly from config. The server does not read the endpoint configuration until it's ready to start the application (after Startup). Even then, that information would be inaccurate much of the time due to reverse proxy setups like IIS, Nginx, docker, etc..

answered Mar 27 '19 at 06:38

TanvirArjel

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But is it possible to get the url inside the class not in startup.cs? – AppleCiderYummy Mar 27 '19 at 06:45
like get the url inside my `public void SomethingToExecute()`? – AppleCiderYummy Mar 27 '19 at 06:46
I hope it is possible. – AppleCiderYummy Mar 27 '19 at 06:46
I'm getting a null value in using `_httpContextAccessor` even after I already add it as singleton in my startup.cs – AppleCiderYummy Mar 27 '19 at 06:52
1

Yes! I am too because application is not started yet completely! Better you store the base url in `appsettings.json` file and retrieve from here or use hard coded. – TanvirArjel Mar 27 '19 at 06:53
are you getting `null` exemption in using `_httpContextAccessor` too sir? – AppleCiderYummy Mar 27 '19 at 06:55
Yes! I am also getting null reference exception. I have made the explanation in the previous comment. – TanvirArjel Mar 27 '19 at 06:56
I'm using hardcoded now which is not realible because if I need to redeploy the app in other machine, it's hassle if I need to republish the app because of changing the hardcoded link – AppleCiderYummy Mar 27 '19 at 06:56
1

That’s why you should store it in appsettings.json. You can change it easily from here after publish. – TanvirArjel Mar 27 '19 at 07:00

score 1 · Answer 2 · answered Apr 01 '19 at 07:06

It seems impossible but alternatively, if you want to invoke the HTTP Request or a Web API using C# Code, you can use HttpClient()

What you can do is combine what @TanvirArjel said and use HttpClient() to invoke the HTTP Request.

Store your host name in appsettings.json

In your SomethingToExecute() use something like this.

private readonly IConfiguration configuration;
public ISomething(IConfiguration configuration){
    this.configuration = configuration;
}

public void SomethingToExecute(){
    var httpClient = new HttpClient();

    var yourHostNameAndPort = configuration["NameFromYourAppSEttingsJsonFile"];

    httpClient.Get("" + yourHostNameAndPort + "...);
}

I hope it helps somebody else too.

score 0 · Answer 3 · answered Mar 27 '19 at 08:37

As TanvirArjel already mentioned it seems impossible. But in your case you can dynamically get host name in your code body.

(Tested in .Net Core 2.1)

Startup.cs

public void ConfigureServices(IServiceCollection services)
{
    services.AddMvc().SetCompatibilityVersion(CompatibilityVersion.Version_2_1);
    services.AddSingleton<something>();
}

something.cs

public class something
{
    public string url;

    public string SomethingToExecute()
    {
        return url;
    }

}

Controller

[ApiController]
public class HomeController : ControllerBase
{

    private something _sth;

    public HomeController(something sth)
    {
        _sth = sth;
    }

    [HttpGet("foo")]
    public string foo()
    {

        _sth.url = Request.Scheme + "://" + Request.Host;
        return _sth.SomethingToExecute();

    }

}

score 0 · Answer 4 · answered Jul 02 '20 at 10:32

For the host name - you can get easily it inside your controller by using Dns.GetHostName(). There is also another way is to get it from the HttpRequestContext like Startup.cs => ConfigureServices => services.AddHttpContextAccessor();

Controler => ctor => use IHttpContextAccessor and then in the controller methods

HttpContextAccessor.HttpContext.Request.Host.Host HttpContextAccessor.HttpContext.Request.Host.Port

However, HttpRequetsContext info is not very trustful.

Probably the best way to get host and port is discussed here already: Determine port Kestrel binded to

score 0 · Answer 5 · answered Jun 28 '21 at 19:20

This alternative option may be useful, set the hostname in your appsettings.{Environment}.json and get the value through IConfiguration:

private readonly IConfiguration _configuration;
public Startup(IConfiguration configuration){
    _configuration = configuration;
}
public void ConfigureServices(IServiceCollection services)
{
    var host = _configuration.GetSection("Host").Get<string>();
}

Get the Domain or Host name and Port in Configure of Startup.cs

5 Answers5

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