为什么ASPNET核心从Docker内部从端口80开始？ [英] Why does aspnet core start on port 80 from within Docker?
问题描述
TL; DR：为什么aspnet核心应用程序在Docker映像中的端口80上运行，而在Docker映像之外的端口上运行5000。
TL;DR: Why does an aspnet core app run on port 80 from within a Docker image, but 5000 outside a docker image.
精心制作
我遍历了在这里找到的aspnet核心/ docker教程：
https://docs.microsoft .com / zh-CN / dotnet / core / docker / building-net-docker-images
I went through the aspnet core / docker tutorial found here: https://docs.microsoft.com/en-us/dotnet/core/docker/building-net-docker-images
通过页面的一半方法，我使用规定如下：
Half way through the page, I start the application with the following as prescribed:
dotnet run
在其他事物中，此打印如下：
Among other things, this prints this:
Now Listening on: http://localhost:5000
很好。那是我的期望。本教程的下一步是从Docker映像中启动完全相同的应用程序。
Great. That is what I expected. The next thing in the tutorial is to start the exact same application from within a Docker image.
docker build -t aspnetapp .
docker run -it --rm -p 5000:80 --name aspnetcore_sample aspnetapp
结果是
Now listening on: http://[::]:80
等待。 ？ 为什么aspnet核心应用程序在端口80上运行？当我直接从计算机上运行它时，它在端口5000上运行。没有配置文件更改。
Wait. Wat? Why is the aspnet core app running on port 80? It was running on port 5000 when I ran it directly from the machine. There were no configuration file changes.
我怀疑它与基本docker映像有关，但是对docker的掌握还不够熟练。
I suspect that it has something to do with the base docker images, but am not yet skilled enough in docker to track this down.
推荐答案
microsoft / aspnetcore-build 容器构建在 容器。 dockerhub页面表示：
microsoft / aspnetcore
The microsoft/aspnetcore-build container builds on top of the
microsoft/aspnetcore container. The dockerhub page for that says:
端口说明
A note on ports
此图像将ASPNETCORE_URLS环境变量设置为 http：// +：80 ，这意味着如果您没有通过在Program.cs中通过app.UseUrl在应用程序中显式设置URL，则您的应用程序将侦听容器内部的端口80。
This image sets the ASPNETCORE_URLS environment variable to http://+:80 which means that if you have not explicity set a URL in your application, via app.UseUrl in your Program.cs for example, then your application will be listening on port 80 inside the container.
因此，这是容器将端口主动设置为80的方式。想要，通过在您的 Dockerfile 中执行此操作：
So this is the container actively setting the port to 80. You can override it, if you want, by doing this in your Dockerfile:
ENV ASPNETCORE_URLS = http：// +：5000
另外，值得注意的是，由于您使用的是docker命令，无论您是否仍然可以通过 http：// localhost：5000 访问应用程序直接或在容器中运行应用程序。
Also, it is worth noting that because of the docker command you are using, you will still be able to access the application at http://localhost:5000 whether you are running the application directly or in a container.
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