容器技術之Docker私有鏡像倉庫docker-distribution

docker倉庫就是用來存放鏡像的地方；其實docker registry我們理解為存放docker鏡像倉庫的倉庫比較準確吧；因為docker的鏡像倉庫通常是把同一類的鏡像用不同的版本來區別，而registry則是用來存放這些倉庫的倉庫；預設安裝docker都是從dockerhub鏡像倉庫下載鏡像... ...

　　在前邊的博客中我們說到docker的架構由docker客戶端、服務端以及倉庫組成；docker倉庫就是用來存放鏡像的地方；其實docker registry我們理解為存放docker鏡像倉庫的倉庫比較準確吧；因為docker的鏡像倉庫通常是把同一類的鏡像用不同的版本來區別，而registry則是用來存放這些倉庫的倉庫；預設安裝docker都是從dockerhub鏡像倉庫下載鏡像；其實在生產環境中，我們很少去公有倉庫上下載鏡像，原因之一是公有倉庫中的鏡像在生產環境中使用，有些不適配，通常我們是去公有倉庫下載基礎鏡像，然後基於基礎鏡像構建適合自己生產環境中的鏡像；其次公有倉庫鏡像有很多都不是安全的鏡像，這麼說吧，我們不確定自己下載的鏡像是否有後門，是否有挖礦代碼，所以基於種種因素，我們還是有必要搭建自己私有的鏡像倉庫；今天我們就來聊一聊docker的私有鏡像倉庫的搭建；

　　1、查看docker-distribution包簡介

[root@docker_registry ~]# yum info docker-distribution
Loaded plugins: fastestmirror
Loading mirror speeds from cached hostfile
 * base: mirrors.aliyun.com
 * extras: mirrors.aliyun.com
 * updates: mirrors.aliyun.com
Available Packages
Name        : docker-distribution
Arch        : x86_64
Version     : 2.6.2
Release     : 2.git48294d9.el7
Size        : 3.5 M
Repo        : extras/7/x86_64
Summary     : Docker toolset to pack, ship, store, and deliver content
URL         : https://github.com/docker/distribution
License     : ASL 2.0
Description : Docker toolset to pack, ship, store, and deliver content

[root@docker_registry ~]#

　　提示：docker-distribution這個包就是提供簡單倉庫服務軟體實現；

　　2、安裝docker-distribution

[root@docker_registry ~]# yum install -y docker-distribution
Loaded plugins: fastestmirror
Loading mirror speeds from cached hostfile
 * base: mirrors.aliyun.com
 * extras: mirrors.aliyun.com
 * updates: mirrors.aliyun.com
Resolving Dependencies
There are unfinished transactions remaining. You might consider running yum-complete-transaction, or "yum-complete-transaction --cleanup-only" and "yum history redo last", first to finish them. If those don't work you'll have to try removing/installing packages by hand (maybe package-cleanup can help).
The program yum-complete-transaction is found in the yum-utils package.
--> Running transaction check
---> Package docker-distribution.x86_64 0:2.6.2-2.git48294d9.el7 will be installed
--> Finished Dependency Resolution

Dependencies Resolved

===================================================================================================================
 Package                         Arch               Version                               Repository          Size
===================================================================================================================
Installing:
 docker-distribution             x86_64             2.6.2-2.git48294d9.el7                extras             3.5 M

Transaction Summary
===================================================================================================================
Install  1 Package

Total download size: 3.5 M
Installed size: 12 M
Downloading packages:
docker-distribution-2.6.2-2.git48294d9.el7.x86_64.rpm                                       | 3.5 MB  00:00:03     
Running transaction check
Running transaction test
Transaction test succeeded
Running transaction
  Installing : docker-distribution-2.6.2-2.git48294d9.el7.x86_64                                               1/1 
  Verifying  : docker-distribution-2.6.2-2.git48294d9.el7.x86_64                                               1/1 

Installed:
  docker-distribution.x86_64 0:2.6.2-2.git48294d9.el7                                                              

Complete!
[root@docker_registry ~]#

　　3、查看docker-distribution安裝了那些文件

[root@docker_registry ~]# rpm -ql docker-distribution
/etc/docker-distribution/registry/config.yml
/usr/bin/registry
/usr/lib/systemd/system/docker-distribution.service
/usr/share/doc/docker-distribution-2.6.2
/usr/share/doc/docker-distribution-2.6.2/AUTHORS
/usr/share/doc/docker-distribution-2.6.2/CONTRIBUTING.md
/usr/share/doc/docker-distribution-2.6.2/LICENSE
/usr/share/doc/docker-distribution-2.6.2/MAINTAINERS
/usr/share/doc/docker-distribution-2.6.2/README.md
/var/lib/registry
[root@docker_registry ~]#

　　提示：/etc/docker-distribution/registry/config.yml這個文件用於配置registry的配置文件；/usr/bin/registry是二進位應用程式；/usr/lib/systemd/system/docker-distribution.service 這個文件是docker-distribution的unit file；/var/lib/registry這個目錄用於存放我們上傳到registry上的鏡像存放地；

　　4、查看配置文件

[root@docker_registry ~]# cat /etc/docker-distribution/registry/config.yml
version: 0.1
log:
  fields:
    service: registry
storage:
    cache:
        layerinfo: inmemory
    filesystem:
        rootdirectory: /var/lib/registry
http:
    addr: :5000
[root@docker_registry ~]#

　　提示：這個配置文件是一個yml語法的配置文件，從上面的信息可以看到，預設情況docker-distribution監聽在tcp的5000埠；存放鏡像的目錄是/var/lib/registry/目錄下；

　　5、啟動docker-distribution

[root@docker_registry ~]# systemctl start docker-distribution
[root@docker_registry ~]# ss -tnl
State       Recv-Q Send-Q            Local Address:Port                           Peer Address:Port              
LISTEN      0      128                           *:22                                        *:*                  
LISTEN      0      100                   127.0.0.1:25                                        *:*                  
LISTEN      0      128                          :::22                                       :::*                  
LISTEN      0      100                         ::1:25                                       :::*                  
LISTEN      0      128                          :::5000                                     :::*                  
[root@docker_registry ~]#

　　提示：可以看到5000埠已經處於監聽狀態了；到此docker-distribution就啟動起來了；這個倉庫服務很簡陋，沒有用戶認證功能，預設是基於http通信而非https，所以從某些角度講，不是一個安全的倉庫；所以一般不見在互聯網上使用，在自己的內外環境中可以使用；

　　這裡補充一點，docker的鏡像通常是 registry地址加repository名稱加版本這三部分組成，registry可以是功能變數名稱，可以是ip地址加埠，也可以說功能變數名稱加埠，預設https是443埠，http是80埠，如果不寫埠預設是443而非80（原因是docker預設不支持從http協議的倉庫下載/上傳鏡像）；例如 quay.io/coreos/flannel:v0.12.0-s390x 從這個鏡像名我們就可以知道registry是https://quay.io;repository名稱為coreos/flannel 版本是v0.12.0-s390x;

　　示例：下載第三方倉庫鏡像到本地

　　提示：可以看到下載下來的鏡像名稱就是我們剛纔說的registry+repository+版本；從上面的信息我們可以總結一點，docker鏡像的名稱（標簽）反應了該鏡像來自哪個registry的那個倉庫；所以我們要下載私有鏡像倉庫中的鏡像就需要把加上私有registry的名稱或地址+repository+版本來下載私有鏡像倉庫中的鏡像；同理上傳鏡像也需要寫明上傳到那個registry中的那個repository中去；

　　示例：上傳本地鏡像到私有倉庫

　　提示：要把本地倉庫鏡像傳到私有倉庫中去，首先我們要把本地鏡像打一個新的標簽，按照我們剛纔上面說的邏輯，然後在上傳新打到標簽的鏡像到私有倉庫就可以了；從上面的信息我們看到當我們打好標簽後，上傳鏡像時報錯了，提示我們倉庫不是https的；預設情況docker不支持http明文上傳/下載鏡像；如果我們非要用http上傳下載鏡像我們需要在配置文件中明確的告訴docker非安全倉庫地址；

　　配置docker支持私有倉庫上傳下載鏡像

[root@docker_registry ~]# cat /etc/docker/daemon.json
{
        "registry-mirrors": ["https://registry.docker-cn.com","https://cyr1uljt.mirror.aliyuncs.com"],
        "insecure-registries": ["192.168.0.99:5000"]
}

[root@docker_registry ~]# systemctl daemon-reload    
[root@docker_registry ~]# systemctl restart docker

　　提示：我們通過在配置文件中配置insecure-registries來告訴docker192.168.0.99：5000這個registry是不安全的，但是我們信任這個倉庫，大概就是這個意思嘛；通常我們是寫主機名然後配合hosts文件來解析的方式來對registry解析；從而把鏡像命名為主機名+倉庫名+版本的形式；如下所示；這裡還需要註意一點insecure-registries後面的列表中的倉庫如果有功能變數名稱，功能變數名稱不能有下劃線（“_”），否則重啟docker會起不來；

[root@docker_registry ~]# cat /etc/docker/daemon.json 
{
        "registry-mirrors": ["https://registry.docker-cn.com","https://cyr1uljt.mirror.aliyuncs.com"],
        "insecure-registries": ["192.168.0.99:5000","docker-registry.io:5000"]

}
[root@docker_registry ~]# cat /etc/hosts
127.0.0.1   localhost localhost.localdomain localhost4 localhost4.localdomain4
::1         localhost localhost.localdomain localhost6 localhost6.localdomain6
192.168.0.99 docker-registry.io registry
192.168.0.22 docker-node01.io node01
192.168.0.23 docker-node02.io node02
[root@docker_registry ~]# systemctl restart docker
[root@docker_registry ~]# docker info
Client:
 Debug Mode: false

Server:
 Containers: 0
  Running: 0
  Paused: 0
  Stopped: 0
 Images: 1
 Server Version: 19.03.11
 Storage Driver: overlay2
  Backing Filesystem: xfs
  Supports d_type: true
  Native Overlay Diff: true
 Logging Driver: json-file
 Cgroup Driver: cgroupfs
 Plugins:
  Volume: local
  Network: bridge host ipvlan macvlan null overlay
  Log: awslogs fluentd gcplogs gelf journald json-file local logentries splunk syslog
 Swarm: inactive
 Runtimes: runc
 Default Runtime: runc
 Init Binary: docker-init
 containerd version: 7ad184331fa3e55e52b890ea95e65ba581ae3429
 runc version: dc9208a3303feef5b3839f4323d9beb36df0a9dd
 init version: fec3683
 Security Options:
  seccomp
   Profile: default
 Kernel Version: 3.10.0-693.el7.x86_64
 Operating System: CentOS Linux 7 (Core)
 OSType: linux
 Architecture: x86_64
 CPUs: 4
 Total Memory: 1.785GiB
 Name: docker_registry
 ID: R34V:IG2F:23I6:6WG6:FFQ4:75SV:3UKZ:RFH7:DGCO:QS7V:CS7K:NSH6
 Docker Root Dir: /var/lib/docker
 Debug Mode: false
 Registry: https://index.docker.io/v1/
 Labels:
 Experimental: false
 Insecure Registries:
  192.168.0.99:5000
  docker-registry.io:5000
  127.0.0.0/8
 Registry Mirrors:
  https://registry.docker-cn.com/
  https://cyr1uljt.mirror.aliyuncs.com/
 Live Restore Enabled: false

[root@docker_registry ~]#

　　提示：重啟docker後，如果在docker info 中能夠看到我們配置的內容說明配置生效了；現在我們再來傳我們新打的標簽的鏡像，看看是否能夠傳到我們的私有倉庫呢？

[root@docker_registry ~]# docker images
REPOSITORY                       TAG                 IMAGE ID            CREATED             SIZE
docker-registry.io:5000/centos   7                   b5b4d78bc90c        4 weeks ago         203MB
centos                           7                   b5b4d78bc90c        4 weeks ago         203MB
192.168.0.99:5000/flannel        v0.12.0-s390x       57eade024bfb        2 months ago        56.9MB
quay.io/coreos/flannel           v0.12.0-s390x       57eade024bfb        2 months ago        56.9MB
[root@docker_registry ~]# docker push 192.168.0.99:5000/flannel:v0.12.0-s390x
The push refers to repository [192.168.0.99:5000/flannel]
b67de7789e55: Pushed 
4c4bfa1b47e6: Pushed 
3b7ae8a9c323: Pushed 
fbd88a276dca: Pushed 
271ca11ef489: Pushed 
1f106b41b4d6: Pushed 
v0.12.0-s390x: digest: sha256:3ce5b8d40451787e1166bf6b207c7834c13f7a0712b46ddbfb591d8b5906bfa6 size: 1579
[root@docker_registry ~]# docker push docker-registry.io:5000/centos:7
The push refers to repository [docker-registry.io:5000/centos]
edf3aa290fb3: Pushed 
7: digest: sha256:c2f1d5a9c0a81350fa0ad7e1eee99e379d75fe53823d44b5469eb2eb6092c941 size: 529
[root@docker_registry ~]#

　　提示：可以看到我們上傳的兩個鏡像都完成了上傳沒有報錯，接下來我們去/var/lib/registry/這個目錄，看看是否有這兩個鏡像相關目錄？

[root@docker_registry ~]# tree /var/lib/registry/
/var/lib/registry/
└── docker
    └── registry
        └── v2
            ├── blobs
            │   └── sha256
            │       ├── 13
            │       │   └── 13b80a37370b57f558a2e06092c39224e5d1ebac50e48df0afdeb43cf2303e60
            │       │       └── data
            │       ├── 17
            │       │   └── 176bad61a3a435da03ec603d2bd8f7a69286d92f21f447b17f21f0bc4e085bde
            │       │       └── data
            │       ├── 1b
            │       │   └── 1b56fbc8a8e10830867455c0794a70f5469c154cdc013554daf501aeda3f30fe
            │       │       └── data
            │       ├── 26
            │       │   └── 266247e2e603e1c840f97cb4d97a08b9184344e9802966cb42c93d21c407839f
            │       │       └── data
            │       ├── 3c
            │       │   └── 3ce5b8d40451787e1166bf6b207c7834c13f7a0712b46ddbfb591d8b5906bfa6
            │       │       └── data
            │       ├── 42
            │       │   └── 42d8e66fa893de4beb5d136b787cf182b24b7f4972c4212b9493b661ad1d7e85
            │       │       └── data
            │       ├── 52
            │       │   └── 524b0c1e57f8ee5fee01a1decba2f301c324a6513ca3551021264e3aa7341ebc
            │       │       └── data
            │       ├── 57
            │       │   └── 57eade024bfbd48c45ef2bad996c4d6a0fa41b692247294745265af738066813
            │       │       └── data
            │       ├── 85
            │       │   └── 85ecb68de4693bb4093d923f6d1062766e4fa7cbb3bf456a2bc19dd3e6c5e6c6
            │       │       └── data
            │       ├── b5
            │       │   └── b5b4d78bc90ccd15806443fb881e35b5ddba924e2f475c1071a38a3094c3081d
            │       │       └── data
            │       └── c2
            │           └── c2f1d5a9c0a81350fa0ad7e1eee99e379d75fe53823d44b5469eb2eb6092c941
            │               └── data
            └── repositories
                ├── centos
                │   ├── _layers
                │   │   └── sha256
                │   │       ├── 524b0c1e57f8ee5fee01a1decba2f301c324a6513ca3551021264e3aa7341ebc
                │   │       │   └── link
                │   │       └── b5b4d78bc90ccd15806443fb881e35b5ddba924e2f475c1071a38a3094c3081d
                │   │           └── link
                │   ├── _manifests
                │   │   ├── revisions
                │   │   │   └── sha256
                │   │   │       └── c2f1d5a9c0a81350fa0ad7e1eee99e379d75fe53823d44b5469eb2eb6092c941
                │   │   │           └── link
                │   │   └── tags
                │   │       └── 7
                │   │           ├── current
                │   │           │   └── link
                │   │           └── index
                │   │               └── sha256
                │   │                   └── c2f1d5a9c0a81350fa0ad7e1eee99e379d75fe53823d44b5469eb2eb6092c941
                │   │                       └── link
                │   └── _uploads
                └── flannel
                    ├── _layers
                    │   └── sha256
                    │       ├── 13b80a37370b57f558a2e06092c39224e5d1ebac50e48df0afdeb43cf2303e60
                    │       │   └── link
                    │       ├── 176bad61a3a435da03ec603d2bd8f7a69286d92f21f447b17f21f0bc4e085bde
                    │       │   └── link
                    │       ├── 1b56fbc8a8e10830867455c0794a70f5469c154cdc013554daf501aeda3f30fe
                    │       │   └── link
                    │       ├── 266247e2e603e1c840f97cb4d97a08b9184344e9802966cb42c93d21c407839f
                    │       │   └── link
                    │       ├── 42d8e66fa893de4beb5d136b787cf182b24b7f4972c4212b9493b661ad1d7e85
                    │       │   └── link
                    │       ├── 57eade024bfbd48c45ef2bad996c4d6a0fa41b692247294745265af738066813
                    │       │   └── link
                    │       └── 85ecb68de4693bb4093d923f6d1062766e4fa7cbb3bf456a2bc19dd3e6c5e6c6
                    │           └── link
                    ├── _manifests
                    │   ├── revisions
                    │   │   └── sha256
                    │   │       └── 3ce5b8d40451787e1166bf6b207c7834c13f7a0712b46ddbfb591d8b5906bfa6
                    │   │           └── link
                    │   └── tags
                    │       └── v0.12.0-s390x
                    │           ├── current
                    │           │   └── link
                    │           └── index
                    │               └── sha256
                    │                   └── 3ce5b8d40451787e1166bf6b207c7834c13f7a0712b46ddbfb591d8b5906bfa6
                    │                       └── link
                    └── _uploads

65 directories, 26 files
[root@docker_registry ~]#

　　提示：可以看到對應目錄下有兩個子目錄就是以我們上傳的鏡像名稱命名的；

　　示例：查看私有倉庫中存在的進行列表

[root@docker_registry ~]# curl docker-registry.io:5000/v2/_catalog
{"repositories":["centos","flannel"]}
[root@docker_registry ~]#

　　示例：下載私有倉庫中的鏡像到本地

[root@docker_node01 ~]# ip a l ens33
2: ens33: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP qlen 1000
    link/ether 00:0c:29:22:36:7f brd ff:ff:ff:ff:ff:ff
    inet 192.168.0.22/24 brd 192.168.0.255 scope global ens33
       valid_lft forever preferred_lft forever
    inet6 fe80::20c:29ff:fe22:367f/64 scope link 
       valid_lft forever preferred_lft forever
[root@docker_node01 ~]# docker images
REPOSITORY          TAG                 IMAGE ID            CREATED             SIZE
linux1874/myimg     v0.1                e408b1c6e04f        2 weeks ago         1.22MB
wordpress           latest              c3fa1c8546fb        5 weeks ago         540MB
mysql               5.7                 f965319e89de        5 weeks ago         448MB
alpine              v3                  f70734b6a266        6 weeks ago         5.61MB
nginx               1.14-alpine         8a2fb25a19f5        14 months ago       16MB
httpd               2.4.37-alpine       dfd436f9a5d8        17 months ago       91.8MB
[root@docker_node01 ~]# docker pull 192.168.0.99:5000/flannel:v0.12.0-s390x
v0.12.0-s390x: Pulling from flannel
176bad61a3a4: Pull complete 
13b80a37370b: Pull complete 
42d8e66fa893: Pull complete 
266247e2e603: Pull complete 
1b56fbc8a8e1: Pull complete 
85ecb68de469: Pull complete 
Digest: sha256:3ce5b8d40451787e1166bf6b207c7834c13f7a0712b46ddbfb591d8b5906bfa6
Status: Downloaded newer image for 192.168.0.99:5000/flannel:v0.12.0-s390x
192.168.0.99:5000/flannel:v0.12.0-s390x
[root@docker_node01 ~]# docker images
REPOSITORY                  TAG                 IMAGE ID            CREATED             SIZE
linux1874/myimg             v0.1                e408b1c6e04f        2 weeks ago         1.22MB
wordpress                   latest              c3fa1c8546fb        5 weeks ago         540MB
mysql                       5.7                 f965319e89de        5 weeks ago         448MB
alpine                      v3                  f70734b6a266        6 weeks ago         5.61MB
192.168.0.99:5000/flannel   v0.12.0-s390x       57eade024bfb        2 months ago        56.9MB
nginx                       1.14-alpine         8a2fb25a19f5        14 months ago       16MB
httpd                       2.4.37-alpine       dfd436f9a5d8        17 months ago       91.8MB
[root@docker_node01 ~]#

　　提示：下載私有倉庫中的鏡像，預設情況docker也是不支持直接訪問http協議的倉庫，需要我們手動去配置insecure-registries，然後重啟docker才可以；

　　示例：刪除私有倉庫中的鏡像

　　1、獲取對應鏡像的sha256的值 curl --header "Accept:application/vnd.docker.distribution.manifest.v2+json" -I -X GET http://<registry addr>/v2/<image name>/manifests/<image tag>

　　2、刪除對應鏡像版本元數據 curl -I -X DELETE http://<registry addr>/v2/<image name>/manifests/<image digest>

　　提示：如果響應405方法不被允許；我們需要修改私有倉庫的配置文件，將其配置為允許刪除；如下

[root@docker_registry ~]# cat /etc/docker-distribution/registry/config.yml
version: 0.1
log:
  fields:
    service: registry
storage:
    delete:
        enabled: true
    cache:
        layerinfo: inmemory
    filesystem:
        rootdirectory: /var/lib/registry
http:
    addr: :5000
[root@docker_registry ~]# systemctl restart docker-distribution           
[root@docker_registry ~]# curl -IX DELETE http://docker-registry.io:5000/v2/centos/manifests/sha256:c2f1d5a9c0a81350fa0ad7e1eee99e379d75fe53823d44b5469eb2eb6092c941
HTTP/1.1 202 Accepted
Docker-Distribution-Api-Version: registry/2.0
Date: Sat, 06 Jun 2020 19:55:52 GMT
Content-Length: 0
Content-Type: text/plain; charset=utf-8

[root@docker_registry ~]#

　　提示：degest值包含"sha256:"

　　3、垃圾回收清理

[root@docker_registry ~]# registry garbage-collect /etc/docker-distribution/registry/config.yml 
centos
flannel
flannel: marking manifest sha256:3ce5b8d40451787e1166bf6b207c7834c13f7a0712b46ddbfb591d8b5906bfa6 
flannel: marking blob sha256:57eade024bfbd48c45ef2bad996c4d6a0fa41b692247294745265af738066813
flannel: marking blob sha256:176bad61a3a435da03ec603d2bd8f7a69286d92f21f447b17f21f0bc4e085bde
flannel: marking blob sha256:13b80a37370b57f558a2e06092c39224e5d1ebac50e48df0afdeb43cf2303e60
flannel: marking blob sha256:42d8e66fa893de4beb5d136b787cf182b24b7f4972c4212b9493b661ad1d7e85
flannel: marking blob sha256:266247e2e603e1c840f97cb4d97a08b9184344e9802966cb42c93d21c407839f
flannel: marking blob sha256:1b56fbc8a8e10830867455c0794a70f5469c154cdc013554daf501aeda3f30fe
flannel: marking blob sha256:85ecb68de4693bb4093d923f6d1062766e4fa7cbb3bf456a2bc19dd3e6c5e6c6
myweb
myweb: marking manifest sha256:aaf04cf567a776e36eb3b0bafaec17ed8d9e0a743bdb897dca13f251250ae493 
myweb: marking blob sha256:4f406abeaab7f848178867409142090d1a551b22b968be6a6dae733c8403738e
myweb: marking blob sha256:524b0c1e57f8ee5fee01a1decba2f301c324a6513ca3551021264e3aa7341ebc
myweb: marking blob sha256:c941076f9075280c41b502283f37ab8bafef3a66f4a7ba299838dce07641a48d
test
test: marking manifest sha256:5ecad23ab8a52e55f93968f708d325261032dd613287aec92e7cf8ddd6426635 
test: marking blob sha256:370e3a843c3cb12700301e3f87f929939146cd8b676260bedcd83aaa7fcc2939
test: marking blob sha256:524b0c1e57f8ee5fee01a1decba2f301c324a6513ca3551021264e3aa7341ebc
test: marking manifest sha256:da8b53210bf1f4dc4873bbd5589abad616663cda45205ae3a4fffb0729d2730d 
test: marking blob sha256:461f6ceabc885e2e90b5f9ee82aefc9a30a39510c40e7cd8fb7436a4d340fe1d
test: marking blob sha256:524b0c1e57f8ee5fee01a1decba2f301c324a6513ca3551021264e3aa7341ebc
test: marking blob sha256:035e026f1d6b0acba3413ba616dcbabf75d20e945778c52716e601255452b7b7

17 blobs marked, 2 blobs eligible for deletion
blob eligible for deletion: sha256:b5b4d78bc90ccd15806443fb881e35b5ddba924e2f475c1071a38a3094c3081d
INFO[0000] Deleting blob: /docker/registry/v2/blobs/sha256/b5/b5b4d78bc90ccd15806443fb881e35b5ddba924e2f475c1071a38a3094c3081d  go.version=go1.9.4 instance.id=b3029d7f-99e8-4941-8c87-989514b584ea
blob eligible for deletion: sha256:c2f1d5a9c0a81350fa0ad7e1eee99e379d75fe53823d44b5469eb2eb6092c941
INFO[0000] Deleting blob: /docker/registry/v2/blobs/sha256/c2/c2f1d5a9c0a81350fa0ad7e1eee99e379d75fe53823d44b5469eb2eb6092c941  go.version=go1.9.4 instance.id=b3029d7f-99e8-4941-8c87-989514b584ea
[root@docker_registry ~]#

　　測試：下載docker-registry.io:5000/centos:7 看看是否還能下載？

[root@docker_node01 ~]# docker pull 192.168.0.99:5000/centos:7
Error response from daemon: manifest for 192.168.0.99:5000/centos:7 not found: manifest unknown: manifest unknown
[root@docker_node01 ~]#

　　提示：以上提示告訴我們沒有對應鏡像的元數據信息；說明我們私有倉庫沒有對應鏡像；以上方法適合精準刪除某個鏡像的某個版本，如果是刪除一個倉庫，直接刪除 /var/lib/registry/docker/registry/v2/repositories/下對應倉庫的目錄，然後在用registry命令做垃圾回收；如下

[root@docker_registry ~]# ll /var/lib/registry/docker/registry/v2/repositories/
total 0
drwxr-xr-x 5 root root 55 Jun  6 14:16 centos
drwxr-xr-x 5 root root 55 Jun  6 14:15 flannel
drwxr-xr-x 5 root root 55 Jun  6 15:25 myweb
drwxr-xr-x 5 root root 55 Jun  6 15:24 test
[root@docker_registry ~]# rm -rf /var/lib/registry/docker/registry/v2/repositories/test
[root@docker_registry ~]# rm -rf /var/lib/registry/docker/registry/v2/repositories/myweb
[root@docker_registry ~]# ll /var/lib/registry/docker/registry/v2/repositories/
total 0
drwxr-xr-x 5 root root 55 Jun  6 14:16 centos
drwxr-xr-x 5 root root 55 Jun  6 14:15 flannel
[root@docker_registry ~]# registry garbage-collect /etc/docker-distribution/registry/config.yml 
centos
flannel
flannel: marking manifest sha256:3ce5b8d40451787e1166bf6b207c7834c13f7a0712b46ddbfb591d8b5906bfa6 
flannel: marking blob sha256:57eade024bfbd48c45ef2bad996c4d6a0fa41b692247294745265af738066813
flannel: marking blob sha256:176bad61a3a435da03ec603d2bd8f7a69286d92f21f447b17f21f0bc4e085bde
flannel: marking blob sha256:13b80a37370b57f558a2e06092c39224e5d1ebac50e48df0afdeb43cf2303e60
flannel: marking blob sha256:42d8e66fa893de4beb5d136b787cf182b24b7f4972c4212b9493b661ad1d7e85
flannel: marking blob sha256:266247e2e603e1c840f97cb4d97a08b9184344e9802966cb42c93d21c407839f
flannel: marking blob sha256:1b56fbc8a8e10830867455c0794a70f5469c154cdc013554daf501aeda3f30fe
flannel: marking blob sha256:85ecb68de4693bb4093d923f6d1062766e4fa7cbb3bf456a2bc19dd3e6c5e6c6

8 blobs marked, 9 blobs eligible for deletion
blob eligible for deletion: sha256:370e3a843c3cb12700301e3f87f929939146cd8b676260bedcd83aaa7fcc2939
INFO[0000] Deleting blob: /docker/registry/v2/blobs/sha256/37/370e3a843c3cb12700301e3f87f929939146cd8b676260bedcd83aaa7fcc2939  go.version=go1.9.4 instance.id=1a15f1e7-194f-4a82-b79d-9f437d975f6e
blob eligible for deletion: sha256:524b0c1e57f8ee5fee01a1decba2f301c324a6513ca3551021264e3aa7341ebc
INFO[0000] Deleting blob: /docker/registry/v2/blobs/sha256/52/524b0c1e57f8ee5fee01a1decba2f301c324a6513ca3551021264e3aa7341ebc  go.version=go1.9.4 instance.id=1a15f1e7-194f-4a82-b79d-9f437d975f6e
blob eligible for deletion: sha256:5ecad23ab8a52e55f93968f708d325261032dd613287aec92e7cf8ddd6426635
INFO[0000] Deleting blob: /docker/registry/v2/blobs/sha256/5e/5ecad23ab8a52e55f93968f708d325261032dd613287aec92e7cf8ddd6426635  go.version=go1.9.4 instance.id=1a15f1e7-194f-4a82-b79d-9f437d975f6e
blob eligible for deletion: sha256:aaf04cf567a776e36eb3b0bafaec17ed8d9e0a743bdb897dca13f251250ae493
INFO[0000] Deleting blob: /docker/registry/v2/blobs/sha256/aa/aaf04cf567a776e36eb3b0bafaec17ed8d9e0a743bdb897dca13f251250ae493  go.version=go1.9.4 instance.id=1a15f1e7-194f-4a82-b79d-9f437d975f6e
blob eligible for deletion: sha256:035e026f1d6b0acba3413ba616dcbabf75d20e945778c52716e601255452b7b7
INFO[0000] Deleting blob: /docker/registry/v2/blobs/sha256/03/035e026f1d6b0acba3413ba616dcbabf75d20e945778c52716e601255452b7b7  go.version=go1.9.4 instance.id=1a15f1e7-194f-4a82-b79d-9f437d975f6e
blob eligible for deletion: sha256:461f6ceabc885e2e90b5f9ee82aefc9a30a39510c40e7cd8fb7436a4d340fe1d
INFO[0000] Deleting blob: /docker/registry/v2/blobs/sha256/46/461f6ceabc885e2e90b5f9ee82aefc9a30a39510c40e7cd8fb7436a4d340fe1d  go.version=go1.9.4 instance.id=1a15f1e7-194f-4a82-b79d-9f437d975f6e
blob eligible for deletion: sha256:4f406abeaab7f848178867409142090d1a551b22b968be6a6dae733c8403738e
INFO[0000] Deleting blob: /docker/registry/v2/blobs/sha256/4f/4f406abeaab7f848178867409142090d1a551b22b968be6a6dae733c8403738e  go.version=go1.9.4 instance.id=1a15f1e7-194f-4a82-b79d-9f437d975f6e
blob eligible for deletion: sha256:c941076f9075280c41b502283f37ab8bafef3a66f4a7ba299838dce07641a48d
INFO[0000] Deleting blob: /docker/registry/v2/blobs/sha256/c9/c941076f9075280c41b502283f37ab8bafef3a66f4a7ba299838dce07641a48d  go.version=go1.9.4 instance.id=1a15f1e7-194f-4a82-b79d-9f437d975f6e
blob eligible for deletion: sha256:da8b53210bf1f4dc4873bbd5589abad616663cda45205ae3a4fffb0729d2730d
INFO[0000] Deleting blob: /docker/registry/v2/blobs/sha256/da/da8b53210bf1f4dc4873bbd5589abad616663cda45205ae3a4fffb0729d2730d  go.version=go1.9.4 instance.id=1a15f1e7-194f-4a82-b79d-9f437d975f6e
[root@docker_registry ~]#

　　提示：這種方式比較粗暴簡單，通常是一個倉庫里只有一個版本鏡像可以使用這種方式刪除，如果一個倉庫有多個版本，那麼還是建議使用第一種方式；