“曝光”之间的区别和“发布”在码头 [英] Difference between "expose" and "publish" in docker

问题描述

我正在尝试Dockerfiles，我认为我理解大部分的逻辑。但是，我看不到在这种情况下暴露和发布一个端口的区别。

我看到的所有教程首先包括 EXPOSE 命令在Dockerfile中：

  ... 
 EXPOSE 8080 
 ... 
  

然后他们从这个Dockerfile构建一个图像：

  $ docker build -t an_image  - < Dockerfile 
  

然后在运行图像时发布与上述相同的端口：

  $ docker run -d -p 8080 an_image 
  

或使用

发布所有端口

  $ docker run -d -P an_image 
  

在Dockerfile中暴露端口的要点是什么？有没有必要首先公开港口，而不是稍后发布？实际上，我想在创建图像时指定我将在Docker文件中使用的所有端口，然后再重新打开它们，只需运行它们：

  $ docker run -d an_image 
  

这是可能吗？ p>

解决方案

基本上，您有三个选项：

• 既不指定 EXPOSE 也不指定 -p 。


• 仅指定 EXPOSE 。


• 指定 EXPOSE 和 -p 。



如果您没有指定任何一个，则容器中的服务将无法从任何地方访问，从容器本身开始。

如果您的端口 c> EXPOSE ，容器中的服务无法从外部访问Docker，但从其他Docker容器内部。所以这对于集装箱间通信是有好处的。

如果您 EXPOSE 和 -p 一个端口，容器中的服务可以从任何地方访问，甚至可以在Docker外部访问。

两者分开的原因是IMHO，因为

• 选择主机端口取决于主机，因此不属于Dockerfile（否则将取决于主机），


• ，如果容器中的服务可从其他容器访问，通常就足够了。

文档明确指出：

EXPOSE 指令会显示在链接中使用的端口。

它还指出了如何链接容器，这些基本上是inter-容器

PS：如果你执行 -p ，但不要 EXPOSE ，Docker执行隐式 EXPOSE 。这是因为如果一个端口对公众开放，它将自动对其他Docker容器开放。因此 -p 包括 EXPOSE 。这就是为什么我没有列出它作为第四种情况。

I'm experimenting with Dockerfiles, and I think I understand most of the logic. However, I don't see the difference between "exposing" and "publishing" a port in this context.

All the tutorials I have seen first include the EXPOSE command in the Dockerfile:

...
EXPOSE 8080
...

They then build an image from this Dockerfile:

$ docker build -t an_image - < Dockerfile

And then publish the same port as above when running the image:

$ docker run -d -p 8080 an_image

or publish all ports using

$ docker run -d -P an_image

What is the point of exposing a port in the Dockerfile, if it will be published anyway? Would there ever be a need to expose a port first, and not publish it later? Effectively, I would like to specify all the ports that I will use in the Dockerfile when creating the image, and then not bother with them again, running them simply with:

$ docker run -d an_image

Is this possible?

解决方案

Basically, you have three options:

• Neither specify EXPOSE nor -p.
• Only specify EXPOSE.
• Specify EXPOSE and -p.

If you do not specify any of those, the service in the container will not be accessible from anywhere except from inside the container itself.

If you EXPOSE a port, the service in the container is not accessible from outside Docker, but from inside other Docker containers. So this is good for inter-container communication.

If you EXPOSE and -p a port, the service in the container is accessible from anywhere, even outside Docker.

The reason why both are separated is IMHO because

• choosing a host port depends on the host and hence does not belong to the Dockerfile (otherwise it would be depending on the host),
• and often it's enough if a service in a container is accessible from other containers.

The documentation explicitly states:

The EXPOSE instruction exposes ports for use within links.

It also points you to how to link containers, which basically is the inter-container communication I talked about.

PS: If you do -p, but do not EXPOSE, Docker does an implicit EXPOSE. This is because if a port is open to the public, it is automatically also open to other Docker containers. Hence -p includes EXPOSE. That's why I didn't list it above as a fourth case.

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