介绍

为了学习ansible，我需要一个“远程”服务器，并且保证可以通过ssh通信。此时，一个运行了sshd的Docker应该可以很好的充当这个角色。

网上搜了下发现一些教程：

然后，就打算自己试写一个 Dockerfile 。

Dockerfile

内容如下，比较简单：

Ubuntu 版本

FROM ubuntu

# PUBLIC_KEY holds the content of host ssh public key, you should assign it when invoking
# the build. E.g. $ docker build --build-arg PUBLIC_KEY="$(cat ~/.ssh/id_rsa.pub)" .
ARG PUBLIC_KEY

# python is needed in managed node
RUN apt-get update && apt-get install -y \
    openssh-server \
    python-simplejson

# sshd needs this directory
RUN mkdir /var/run/sshd

# remember the public key of the host
RUN mkdir /root/.ssh/
RUN echo $PUBLIC_KEY >> /root/.ssh/authorized_keys

EXPOSE 22

CMD ["/usr/sbin/sshd", "-D"]

Centos 版本

FROM centos:6.8

# PUBLIC_KEY holds the content of host ssh public key, you should assign it when invoking
# the build. E.g. $ docker build --build-arg PUBLIC_KEY="$(cat ~/.ssh/id_rsa.pub)" .
ARG PUBLIC_KEY

RUN yum update -y && yum install -y \
    openssh-server \
    python-simplejson

# sshd needs this directory
RUN mkdir /var/run/sshd

# remember the public key of the host
RUN mkdir /root/.ssh/
RUN echo $PUBLIC_KEY >> /root/.ssh/authorized_keys

# ensure the host keys are generated
RUN ["/sbin/service", "sshd", "start"]
RUN ["/sbin/service", "sshd", "stop"]

EXPOSE 22

CMD ["/usr/sbin/sshd", "-D"]

登录SSH慢

容器内部启动sshd，从宿主机登录可能会需要几十秒到几分钟的延迟。有如下原因和解决方案（参考自这里）:

当然，每次设置完毕之后都要reload一下sshd (SIGHUP)

Build

执行：

$ docker build -t ssh --build-arg PUBLIC_KEY="$(cat ~/.ssh/id_rsa.pub)" .

Run

启动容器：

$ docker run --rm  -Pd ssh

如果需要用主机的 IP 去连，则可以检查下容器22端口映射到主机的端口:

$ docker port <container>
22/tcp -> 0.0.0.0:32773

如果直接以容器的IP去连，则可以检查下容器的IP：

$ docker container inspect <container> | grep IPAddress -C 3
                ]
            },
            "SandboxKey": "/var/run/docker/netns/4e5bfb98fffb",
            "SecondaryIPAddresses": null,
            "SecondaryIPv6Addresses": null,
            "EndpointID": "977e34e90bcb25e29c71c50436e76bad3517498d897fa5d61e4228d403cf93ff",
            "Gateway": "170.17.0.1",
            "GlobalIPv6Address": "",
            "GlobalIPv6PrefixLen": 0,
            "IPAddress": "170.17.0.2",
            "IPPrefixLen": 16,
            "IPv6Gateway": "",
            "MacAddress": "02:42:aa:11:00:02",
--
                    "NetworkID": "6a46a90c45ce75e0773a834cba5dcc4b9952086cce67c82e6686ba6f0e89194f",
                    "EndpointID": "977e34e90bcb25e29c71c50436e76bad3517498d897fa5d61e4228d403cf93ff",
                    "Gateway": "170.17.0.1",
                    "IPAddress": "170.17.0.2",
                    "IPPrefixLen": 16,
                    "IPv6Gateway": "",
                    "GlobalIPv6Address": "",

连接容器：

$ ssh -p 32773 root@127.0.0.1
# OR
$ ssh root@170.17.0.2

Clean Up

$ docker container stop <container>
$ docker image rm ssh