.Net Core API 连接在 Docker 容器内的端口 5000 上被拒绝

Question

I created a.Net Core 3.1 API which I want to run in a Docker container.

The project structure is as follows:

• MyBackendAPI
  • Dockerfile
  • Program.cs
  • Startup.cs
  • Controllers
    • MailController.cs
  • ...
• MyBackendAPI.sln

In my MailController.cs I have a service

[HttpPost]
[Route("sendmail/{mailCustomer}/{nameCustomer}/{messageText}")]
public void SendMail(string mailCustomer, string nameCustomer, string messageText)
{
    // do something
}

The Dockerfile has this content:

FROM mcr.microsoft.com/dotnet/core/sdk:3.1 AS build
WORKDIR /app
COPY . /app
RUN dotnet build
EXPOSE 5000
ENTRYPOINT ["dotnet", "run"]

When I run docker build. -t do.netcoreapp docker build. -t do.netcoreapp everything works. When I start the container by docker run do.netcoreapp it gives that output.

info: Microsoft.Hosting.Lifetime[0]
Now listening on: http://127.0.0.1:5000
info: Microsoft.Hosting.Lifetime[0]
    Application started. Press Ctrl+C to shut down.
info: Microsoft.Hosting.Lifetime[0]
    Hosting environment: Development
info: Microsoft.Hosting.Lifetime[0]
    Content root path: /app

Everything seems to be fine. But when I request the API in Postman via http://localhost:5000/mail/sendmail/mymail@mail.com/Edgar/abc I get Error: connect ECONNREFUSED 127.0.0.1:5000 .

By running the command docker container ls I see that my container is running and listening on port 5000:

CONTAINER ID   IMAGE           COMMAND        CREATED          STATUS          PORTS      NAMES
8abbb2fc90d0   dotnetcoreapp   "dotnet run"   14 minutes ago   Up 14 minutes   5000/tcp   quirky_kirch

When I do the same request while my application is not running inside a docker container everything works. Does anyone know what the problem is?

Answer 1

You are mapping port 8080 to port 5000, but if you look at the log file your app is listening on port 80. Change the option to -p 80:5000.