linux - Docker 容器作为 Linux 服务？

Question

我刚刚创建了一个安全的 Docker Registry并在远程 VM 上运行它(使用 docker run ...)。然后我运行 docker ps 并看到它实际上正在运行。我退出机器，然后通过 SSH 重新登录。我再次运行 docker ps 并验证它在我退出 SSH session 时“幸存”。

这让我想知道:Docker 容器实际上作为 Linux 服务运行吗？如果不是，是否有任何方法可以让它们作为传统的(upstart- 或 systemd-based) 服务？这样做有什么理由/优点吗？

Answer 1

docker 引擎作为守护进程运行。
在“Host integration”中提到:

As of Docker 1.2, restart policies are the built-in Docker mechanism for restarting containers when they exit. If set, restart policies will be used when the Docker daemon starts up, as typically happens after a system boot. Restart policies will ensure that linked containers are started in the correct order.

If restart policies don’t suit your needs (i.e., you have non-Docker processes that depend on Docker containers), you can use a process manager like upstart, systemd or supervisor instead.

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顺便说一句，这涉及(当容器运行时带有某些选项)一些安全问题:参见 issue 14767和 issue 6401 :

The container (with --net host option) is the host when it comes to the network stack so any services running on the host are accessible to the container. It just so happens that you communicate to upstart ( and others ) this way.

This feature is a runtime only option, just like the --privileged flag, therefore an image cannot request this, it must be explicitly set at runtime.