1、为什么要删除私有镜像仓库中镜像？

1.1、如何搭建私有镜像仓库

请参考
基于registry镜像构建本地镜像仓库

1.2、需要删除镜像的场景

比如，要编译k8s，需要kube-cross镜像，当前最新的版本V1.13.6-1
而编译k8s 1.17.0需要 V1.13.4-1
可能在上传镜像到私有镜像仓库的时候将V1.13.6-1的kube-cross tag成了V1.13.4-1，编译k8s的时候，出现版本不匹配导致编译失败
此时就需要删除私有镜像仓库中的kube-cross版本

# docker tag 192.168.166.180:50500/kube-cross:v1.13.6-1 192.168.166.180:50500/kube-cross:v1.13.4-1
# docker push 192.168.166.180:50500/kube-cross:v1.13.4-1
The push refers to repository [10.43.166.180:50500/kube-cross]
4bd71a18d78f: Layer already exists
022eea37cee0: Layer already exists
7e34d1e37033: Layer already exists
24af9960442d: Layer already exists
271b7f26a286: Layer already exists
64cbc4bfc2f3: Layer already exists
ec13f1004587: Layer already exists
e5abe1112ca1: Layer already exists
efdff2422869: Layer already exists
3d6d182dab88: Layer already exists
e6d60910d056: Layer already exists
b52c1c103fae: Layer already exists
6f1c84e6ec59: Layer already exists
dd5242c2dc8a: Layer already exists
v1.13.4-1: digest: sha256:df0a50772214025040ea31144a731b5fa76944cbfc9c87db05af98e4aa39aa7f size: 3274

还有可能是镜像仓库满了，需要删除一些不需要的或者版本比较老的镜像

2、删除镜像

2.1、查看镜像列表

# curl http://192.168.166.180:50500/v2/_catalog
{"repositories":["debian-base-amd64","debian-iptables-amd64","kube-cross","registry"]}

2.2、修改registry容器配置文件

registry v2版本的镜像，默认是不允许删除镜像的，所以需要修改配置文件，使能删除方法

2.2.1、查看registry容器ID

# docker ps
CONTAINER ID        IMAGE               COMMAND                  CREATED             STATUS              PORTS                     NAMES
d697e31fae97        registry            "/entrypoint.sh /etc…"   41 hours ago        Up 41 hours         0.0.0.0:50500->5000/tcp   local-registry

2.2.2、查看配置文件

# docker exec -it d697e31fae97 cat /etc/docker/registry/config.yml
version: 0.1
log:
  fields:
    service: registry
storage:
  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

2.2.3、修改配置文件

增加 delete段，将enabled设置为true

# docker exec -it d697e31fae97 vi /etc/docker/registry/config.yml

2.2.4、查看修改后的配置文件

# docker exec -it d697e31fae97 cat /etc/docker/registry/config.yml
version: 0.1
log:
  fields:
    service: registry
storage:
  cache:
    blobdescriptor: inmemory
  filesystem:
    rootdirectory: /var/lib/registry
  delete:
    enabled: true
http:
  addr: :5000
  headers:
    X-Content-Type-Options: [nosniff]
health:
  storagedriver:
    enabled: true
    interval: 10s
    threshold: 3

2.2.5、重启容器生效配置

# docker restart d697e31fae97
d697e31fae97
# docker ps
CONTAINER ID        IMAGE               COMMAND                  CREATED             STATUS              PORTS                     NAMES
d697e31fae97        registry            "/entrypoint.sh /etc…"   41 hours ago        Up 3 seconds        0.0.0.0:50500->5000/tcp   local-registry

2.2、获取镜像摘要信息

# curl --header "Accept: application/vnd.docker.distribution.manifest.v2+json" -I -X GET http://192.168.166.180:50500/v2/kube-cross/manifests/v1.13.4-1
HTTP/1.1 200 OK
Content-Length: 3274
Content-Type: application/vnd.docker.distribution.manifest.v2+json
Docker-Content-Digest: sha256:df0a50772214025040ea31144a731b5fa76944cbfc9c87db05af98e4aa39aa7f
Docker-Distribution-Api-Version: registry/2.0
Etag: "sha256:df0a50772214025040ea31144a731b5fa76944cbfc9c87db05af98e4aa39aa7f"
X-Content-Type-Options: nosniff
Date: Wed, 18 Mar 2020 09:51:02 GMT

摘要为：sha256:df0a50772214025040ea31144a731b5fa76944cbfc9c87db05af98e4aa39aa7f

2.3、删除镜像

# curl -I -X DELETE http://192.168.166.180:50500/v2/kube-cross/manifests/sha256:df0a50772214025040ea31144a731b5fa76944cbfc9c87db05af98e4aa39aa7f
HTTP/1.1 202 Accepted
Docker-Distribution-Api-Version: registry/2.0
X-Content-Type-Options: nosniff
Date: Wed, 18 Mar 2020 09:52:08 GMT
Content-Length: 0

2.4、检查镜像已经不存在

# curl --header "Accept: application/vnd.docker.distribution.manifest.v2+json" -I -X GET http://192.168.166.180:50500/v2/kube-cross/manifests/v1.13.4-1
HTTP/1.1 404 Not Found
Content-Type: application/json; charset=utf-8
Docker-Distribution-Api-Version: registry/2.0
X-Content-Type-Options: nosniff
Date: Wed, 18 Mar 2020 09:53:05 GMT
Content-Length: 99

3、可能遇到的问题

3.1、无删除权限

Method Not Allowed

# curl -I -XDELETE http://192.168.166.180:50500/v2/kube-cross/manifests/sha256:1ca2db35badb4e5ab64ff6478ad550514234e97dcfae3bbfe688b40278c99fc0
HTTP/1.1 405 Method Not Allowed
Content-Type: application/json; charset=utf-8
Docker-Distribution-Api-Version: registry/2.0
X-Content-Type-Options: nosniff
Date: Wed, 18 Mar 2020 09:28:50 GMT
Content-Length: 78

原因是默认情况下，delete方法没有enable
可以参考2.2节修改

3.2、没有找到镜像

# curl -I -XDELETE http://192.168.166.180:50500/v2/kube-cross/manifests/sha256:1ca2db35badb4e5ab64ff6478ad550514234e97dcfae3bbfe688b40278c99fc0
HTTP/1.1 404 Not Found
Content-Type: application/json; charset=utf-8
Docker-Distribution-Api-Version: registry/2.0
X-Content-Type-Options: nosniff
Date: Wed, 18 Mar 2020 09:43:22 GMT
Content-Length: 70

原因可能是获取的摘要不对
registry v2 版本获取摘要的命令需加上这个header
–header “Accept: application/vnd.docker.distribution.manifest.v2+json”