基于alpine用dockerfile创建的ssh镜像

1、下载alpine镜像

[root@docker43 ~]# docker pull alpine
Using default tag: latest
Trying to pull repository docker.io/library/alpine ... 
latest: Pulling from docker.io/library/alpine
4fe2ade4980c: Pull complete 
Digest: sha256:621c2f39f8133acb8e64023a94dbdf0d5ca81896102b9e57c0dc184cadaf5528
Status: Downloaded newer image for docker.io/alpine:latest
[root@docker43 ~]# docker images
REPOSITORY          TAG                 IMAGE ID            CREATED             SIZE
docker.io/alpine    latest              196d12cf6ab1        3 weeks ago         4.41 MB

2、编写dockerfile

2.1.创建一个工作目录

[root@docker43 ~]# cd /opt/
[root@docker43 opt]# mkdir alpine_ssh && cd alpine_ssh && touch Dockerfile

[root@docker43 alpine_ssh]# ll
总用量 4
-rw-r--r-- 1 root root 654 10月  3 23:21 Dockerfile

2.2.编写Dockerfile

# 指定创建的基础镜像
FROM alpine

# 作者描述信息
MAINTAINER alpine_sshd (zhujingzhi@123.com)

# 替换阿里云的源
RUN echo "http://mirrors.aliyun.com/alpine/latest-stable/main/" > /etc/apk/repositories
RUN echo "http://mirrors.aliyun.com/alpine/latest-stable/community/" >> /etc/apk/repositories

# 同步时间

# 更新源、安装openssh 并修改配置文件和生成key 并且同步时间
RUN apk update && \
    apk add --no-cache openssh-server tzdata && \
    cp /usr/share/zoneinfo/Asia/Shanghai /etc/localtime && \
    sed -i "s/#PermitRootLogin.*/PermitRootLogin yes/g" /etc/ssh/sshd_config && \
    ssh-keygen -t rsa -P "" -f /etc/ssh/ssh_host_rsa_key && \
    ssh-keygen -t ecdsa -P "" -f /etc/ssh/ssh_host_ecdsa_key && \
    ssh-keygen -t ed25519 -P "" -f /etc/ssh/ssh_host_ed25519_key && \
    echo "root:admin" | chpasswd

# 开放22端口
EXPOSE 22

# 执行ssh启动命令
CMD ["/usr/sbin/sshd", "-D"]

2.3.创建镜像

# 在dockerfile所在的目录下
[root@docker43 alpine_ssh]# pwd
/opt/alpine_ssh
[root@docker43 alpine_ssh]# docker build -t alpine:sshd .

3、创建容器测试

　　创建容器

[root@docker43 alpine_ssh]# docker run -itd -p 10022:22 --name alpine_ssh_v1 alpine:sshd
[root@docker43 alpine_ssh]# docker ps 
CONTAINER ID        IMAGE               COMMAND               CREATED             STATUS              PORTS                   NAMES
b353f5f3b703        alpine:sshd         "/usr/sbin/sshd -D"   17 minutes ago      Up 17 minutes       0.0.0.0:10022->22/tcp   alpine_ssh_v1

　　测试

[root@docker43 alpine_ssh]# ssh root@127.0.0.1 -p10022
root@127.0.0.1's password: 
Welcome to Alpine!

The Alpine Wiki contains a large amount of how-to guides and general
information about administrating Alpine systems.
See <http://wiki.alpinelinux.org>.

You can setup the system with the command: setup-alpine

You may change this message by editing /etc/motd.

b353f5f3b703:~# 

4、问题总结

　　这些都是我在手动测试的时候遇见的，已经在写Dockerfile的时候加进去了处理方法

1. apk add --no-cache openssh-server   # 安装openssh的问题

/ # apk add --no-cache openssh-server
fetch http://dl-cdn.alpinelinux.org/alpine/v3.8/main/x86_64/APKINDEX.tar.gz
fetch http://dl-cdn.alpinelinux.org/alpine/v3.8/community/x86_64/APKINDEX.tar.gz
(1/3) Installing openssh-keygen (7.7_p1-r2)
ERROR: openssh-keygen-7.7_p1-r2: package mentioned in index not found (try 'apk update')
(2/3) Installing openssh-server-common (7.7_p1-r2)
(3/3) Installing openssh-server (7.7_p1-r2)
ERROR: openssh-server-7.7_p1-r2: package mentioned in index not found (try 'apk update')
2 errors; 4 MiB in 14 packages

原因是：提示源没有这个openssh的包

解决方式：
在dockerfile中改为国内的源
http://mirrors.aliyun.com/alpine/latest-stable/main/
http://mirrors.aliyun.com/alpine/latest-stable/community/

创建容器文件修改
[root@docker43 ~]# docker run -it alpine
/ # vi /etc/apk/repositories 
http://mirrors.aliyun.com/alpine/latest-stable/main/
http://mirrors.aliyun.com/alpine/latest-stable/community/
                                                    
#http://dl-cdn.alpinelinux.org/alpine/v3.8/main     
#http://dl-cdn.alpinelinux.org/alpine/v3.8/community

# 注释或者删除原来的默认源，添加阿里云的源，然后执行apk update，在进行安装就OK了


2、ssh 启动问题
/ # /etc/init.d/sshd start
/bin/sh: /etc/init.d/sshd: not found

这样的方式不能启动，需要安装一个alpine的管理工具
apk add --no-cache openrc
/ # /etc/init.d/sshd start
 * WARNING: sshd is already starting
 所以使用 /usr/sbin/sshd -D 方式启动。但是又出现如下错误
 / # /usr/sbin/sshd -D
Could not load host key: /etc/ssh/ssh_host_rsa_key
Could not load host key: /etc/ssh/ssh_host_ecdsa_key
Could not load host key: /etc/ssh/ssh_host_ed25519_key
sshd: no hostkeys available -- exiting.
解决方式：
ssh-keygen -t rsa -P "" -f /etc/ssh/ssh_host_rsa_key
ssh-keygen -t ecdsa -P "" -f /etc/ssh/ssh_host_ecdsa_key
ssh-keygen -t ed25519 -P "" -f /etc/ssh/ssh_host_ed25519_key

再次启动
/ # /usr/sbin/sshd -D

启动成功


3、创建容器后的网络问题
[root@docker43 opt]# docker run -it alpine
WARNING: IPv4 forwarding is disabled. Networking will not work.

解决方式：
[root@docker43 ~]# vim /etc/sysctl.conf
net.ipv4.ip_forward=1    # 添加这一行

[root@docker43 ~]# docker run -it alpine
/ #