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Docker Registry

因为众所周知的原因，在国内下载Docker镜像会很慢，所以我们更改docker的配置，让它使用 daocloud的加速服务:

ArchLinux下，编辑以下文件，或者你可以通过sudo systemctl edit docker.service来配置以下 文件:

# vim /etc/systemd/system/docker.service.d/override.conf 
[Service]
ExecStart=
ExecStart=/usr/bin/dockerd --registry-mirror=http://1a653205.m.daocloud.io -H fd://

现在重新加载服务并重新启动docker.service：

# systemctl daemon-reload
# systemctl restart docker.service

从此以后，每一次docker pull都会使用到daocloud提供的加速服务。

本地私有registry

首先pull下来如下镜像(这两个其实是一个镜像):

# docker pull registry:latest
# docker pull registry:2

运行registry实例(注意更改volumn映射):

# docker run -d -p 5000:5000 --restart=always --name registry -v
/root/DockerRegistry:/var/lib/registry registry:2

检查实例运行情况:

➜  ~ sudo docker ps
CONTAINER ID        IMAGE                            COMMAND                  CREATED
STATUS              PORTS                    NAMES
b16b27933709        registry:2                       "/entrypoint.sh /etc/"   7 hours
ago         Up 2 hours          0.0.0.0:5000->5000/tcp   registry

为了让这个服务每次都启动，我们来编写一个systemd服务:

# vim /usr/lib/systemd/system/DockerRegistry.service 
[Unit]
Description=DockerRegistry container
Requires=docker.service
After=docker.service

[Service]
Restart=always
ExecStart=/usr/bin/docker start -a registry
ExecStop=/usr/bin/docker stop -t 2 registry

[Install]
WantedBy=multi-user.target

现在使能该服务:

# systemctl enable DockerRegistry.service
Created symlink /etc/systemd/system/multi-user.target.wants/DockerRegistry.service →
/usr/lib/systemd/system/DockerRegistry.service.

本地私有Registry使用方法

将获取到的image tag到私有registry(tag):

# docker tag ubuntu:16.04 localhost:5000/ubuntu:16.04

将获取到的image push到私有registry(push):

# docker push localhost:5000/ubuntu:16.04

在agent机器上启用本地registry仓库

在systemd类型的机器上，例如Ubuntu16.04上，使用以下命令，添加192.168.177.11:5000这个私有仓库：

# sed -i 's#fd://#fd:// --registry-mirror http://192.168.177.11:5000
--insecure-registry 192.168.177.11:5000#' /lib/systemd/system/docker.service
# systemctl daemon-reload
# systemctl restart docker

添加完毕后，检查docker运行参数:

# ps -ef | grep docker
root      4253     1  2 21:48 ?        00:00:00 /usr/bin/dockerd -H fd://
--registry-mirror http://192.168.177.11:5000 --insecure-registry
192.168.177.11:5000
root      4260  4253  0 21:48 ?        00:00:00 docker-containerd -l
unix:///var/run/docker/libcontainerd/docker-containerd.sock --shim
docker-containerd-shim --metrics-interval=0 --start-timeout 2m --state-dir
/var/run/docker/libcontainerd/containerd --runtime docker-runc

pull一个已经被放入仓库里的镜像，速度非常快:

# docker pull 192.168.177.11:5000/fedora:latest
latest: Pulling from fedora
41b563eedcb0: Pull complete 
Digest:
sha256:cc4323bf2ee99b414600605e42d1888c4c1b0a08f5793a379c1238af4a44315d
Status: Downloaded newer image for 192.168.177.11:5000/fedora:latest

检查安装的镜像:

$ sudo docker run -it 192.168.177.11:5000/fedora /bin/bash
[root@810f44567c87 /]# cat /etc/redhat-release 
Fedora release 24 (Twenty Four)