docker学习---搭建Docker私有库及删除库内镜像

环境准备
系统：

cat /etc/redhat-release
CentOS Linux release 7.4. (Core)

主机两台，分别是docker私有库服务器（IP 192.168.121.121）和用户开发机（IP 192.168.121.122），开发机从私有库服务器拉取镜像。

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1、配置软件源并安装安装docker
两台主机安装docker

yum install docker-ce

2、搭建私有镜像仓库
登陆私有库服务器

创建docker管理账户并设置密码

useradd dkuser
passwd dkuser

把账户加入docker组，这一步是为了可以使用普通账户管理docker，而不用使用sudo命令

usermod -G docker dkuser

为账户配置sudo权限

visudo

添加下面一行
dkuser ALL=(ALL) NOPASSWD:ALL

切换账户

su dkuser

启动docker服务

sudo systemctl start docker

可以通过官方提供的registry镜像来搭建本地的私有仓库，所以拉取官方镜像

docker pull registry

创建存放镜像和docker配置文件的目录

sudo mkdir /data/docker

创建配置文件，storage配置中的delete=true配置项，是为了允许删除镜像。默认的镜像是没有这个参数

sudo vi /data/docker/config.yml

 version: 0.1

 log:
 fields:
 service: registry
 storage:
 delete:
 enabled: true
 cache:
 blobdescriptor: inmemory
 filesystem:
 rootdirectory: /var/lib/registry
 http:
 addr: :5000
 headers:
 X-Content-Type-Options: [nosniff]
 health:
 storagedriver:
 enabled: true
 interval: 10s
 threshold: 3

运行registry容器

docker run -d -p : -v /data/docker/registry:/var/lib/registry -v /data/docker/config.yml:/etc/docker/registry/config.yml --restart always --name registry registry

说明：
-d -p 5000:5000 端口映射
-v /data/docker/registry:/var/lib/registry 默认情况下，会将仓库存放于容器内的/var/lib/registry目录下，指定本地目录挂载到容器
--restart always 在容器退出时总是重启容器,主要应用在生产环境
--name registry 指定容器的名称

查看容器

docker ps
CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES
071105c54db3 registry "/entrypoint.sh /etc…" 3 minutes ago Up About a minute 0.0.0.0:5000->5000/tcp registry

3、把本地镜像上传到私有仓库
在私有库服务器上

这里以busybox镜像为例，因为比较小

首先把镜像下载到本地

docker pull busybox

为镜像打标签

docker tag busybox 192.168.121.121:/busybox

查看镜像

docker images
REPOSITORY TAG IMAGE ID CREATED SIZE
192.168.121.121:5000/busybox latest db8ee88ad75f 7 hours ago 1.22MB
busybox latest db8ee88ad75f 7 hours ago 1.22MB

编辑配置文件，添加配置是为了能够在本地上传镜像。

sudo vi /usr/lib/systemd/system/docker.service 

在 ExecStart=/usr/bin/dockerd 后边添加

--insecure-registry 192.168.121.121:5000

重启docker服务

sudo systemctl daemon-reload
sudo systemctl restart docker

推送镜像到私有库

docker push 192.168.121.121:/busybox
The push refers to repository [192.168.121.121:/busybox]
0d315111b484: Pushed
latest: digest: sha256:895ab622e92e18d6b461d671081757af7dbaa3b00e3e28e12505af7817f73649 size: 

报错解决：

docker push 192.168.121.121:/busybox
The push refers to repository [192.168.121.121:/busybox]
Get https://192.168.121.121:5000/v2/: http: server gave HTTP response to HTTPS client

因为Docker从1.3.X之后，与docker registry交互默认使用的是https，然而此处搭建的私有仓库只提供http服务，所以当与私有仓库交互时就会报上面的错误。为了解决这个问题需要在启动docker server时增加启动参数为默认使用http访问

sudo vi /usr/lib/systemd/system/docker.service 

ExecStart=/usr/bin/dockerd 后边添加

--insecure-registry 192.168.121.121:5000

4、开发机从私有库载入镜像

同样的也需要添加配置

vi /usr/lib/systemd/system/docker.service 

ExecStart=/usr/bin/dockerd 后边添加

--insecure-registry 192.168.121.121:5000

启动docker服务

systemctl start docker

从私有库载入镜像

docker pull 192.168.121.121:/busybox
Using default tag: latest
latest: Pulling from busybox
ee153a04d683: Pull complete
Digest: sha256:895ab622e92e18d6b461d671081757af7dbaa3b00e3e28e12505af7817f73649
Status: Downloaded newer image for 192.168.121.121:/busybox:latest

查看镜像

docker images
REPOSITORY TAG IMAGE ID CREATED SIZE
192.168.121.121:/busybox latest db8ee88ad75f  hours ago .22MB

5、删除镜像
在私有库服务器上

相应的参考命令:
#查询镜像
curl <仓库地址>/v2/_catalog

#查询镜像tag(版本)
curl <仓库地址>/v2/<镜像名>/tags/list

#查询镜像digest_hash
curl --header "Accept:application/vnd.docker.distribution.manifest.v2+json" -I -XGET <仓库地址>/v2/<镜像名>/manifests/<tag>

#删除镜像API
curl -I -X DELETE "<仓库地址>/v2/<镜像名>/manifests/<镜像digest_hash>"

在服务器执行下面命令
查询镜像

curl -XGET http://192.168.121.121:5000/v2/_catalog
{"repositories":["busybox"]}

查询镜像tag

curl http://192.168.121.121:5000/v2/busybox/tags/list
{"name":"busybox","tags":["latest"]}

查询镜像digest_hash，删除命令里边要填写的 镜像digest_hash 就是 查询结果里边 Docker-Content-Digest: 后边的内容

curl --header "Accept:application/vnd.docker.distribution.manifest.v2+json" -I -XGET http://192.168.121.121:5000/v2/busybox/manifests/latest
HTTP/1.1  OK
Content-Length:
Content-Type: application/vnd.docker.distribution.manifest.v2+json
Docker-Content-Digest: sha256:895ab622e92e18d6b461d671081757af7dbaa3b00e3e28e12505af7817f73649
Docker-Distribution-Api-Version: registry/2.0
Etag: "sha256:895ab622e92e18d6b461d671081757af7dbaa3b00e3e28e12505af7817f73649"
X-Content-Type-Options: nosniff
Date: Fri,  Jul  :: GMT

删除私有库镜像

curl -I -XDELETE http://192.168.121.121:5000/v2/busybox/manifests/sha256:895ab622e92e18d6b461d671081757af7dbaa3b00e3e28e12505af7817f73649
HTTP/1.1  Accepted
Docker-Distribution-Api-Version: registry/2.0
X-Content-Type-Options: nosniff
Date: Fri,  Jul  :: GMT
Content-Length: 

查看镜像信息可以看到镜像的标签显示为空 null

curl http://192.168.121.121:5000/v2/busybox/tags/list
{"name":"busybox","tags":null}

这里虽然删除了，但是实际上硬盘地址还没有释放，是因为docker删除p_w_picpath只是删除的p_w_picpath的元数据信息。层数据并没有删除。现在进入registry中进行垃圾回收。

进入registry容器

docker exec -it 071105c54db3 /bin/sh
/ # cd /var/lib/registry/

查看镜像大小

/var/lib/registry # du -sch
.0K .
.0K total

执行回收命令

/var/lib/registry # registry garbage-collect /etc/docker/registry/config.yml
busybox

 blobs marked,  blobs and  manifests eligible for deletion
blob eligible for deletion: sha256:895ab622e92e18d6b461d671081757af7dbaa3b00e3e28e12505af7817f73649
INFO[] Deleting blob: /docker/registry/v2/blobs/sha256//895ab622e92e18d6b461d671081757af7dbaa3b00e3e28e12505af7817f73649 go.version=go1.11.2 instance.id=7c37e39d-6ad1--b9d1-592a900b0902 service=registry
blob eligible for deletion: sha256:db8ee88ad75f6bdc74663f4992a185e2722fa29573abcc1a19186cc5ec09dceb
INFO[] Deleting blob: /docker/registry/v2/blobs/sha256/db/db8ee88ad75f6bdc74663f4992a185e2722fa29573abcc1a19186cc5ec09dceb go.version=go1.11.2 instance.id=7c37e39d-6ad1--b9d1-592a900b0902 service=registry
blob eligible for deletion: sha256:ee153a04d6837058642958836062f20badf39f558be3e6c7c7773ef7d8301d90
INFO[] Deleting blob: /docker/registry/v2/blobs/sha256/ee/ee153a04d6837058642958836062f20badf39f558be3e6c7c7773ef7d8301d90 go.version=go1.11.2 instance.id=7c37e39d-6ad1--b9d1-592a900b0902 service=registry

再次查询，发现回收资源执行成功

/var/lib/registry # du -sch
 .
 total

参考：

https://www.cnblogs.com/Tempted/p/7768694.html
https://blog.csdn.net/jiangeeq/article/details/81056055
https://www.cnblogs.com/HwyStudy/p/10483163.html
https://blog.51cto.com/302876016/1966816