Docker Hub当然是首选镜像仓，如果不想对所有人公开只想在局域网或公司内部使用，则有必要搭建私有仓来存储分发镜像。
搭建私有仓当然可以直接运行以下命令来创建个registry容器：
docker run -d -p : --restart=always --name registry registry:2
一条命令已经很简洁了，这里如果只是写这么一句话就实在太没必要了，所以本文介绍如何一步步编译出registry镜像。
registry官方路径：https://hub.docker.com/_/registry/
Docker registry镜像依赖关系是registry:latest -> alpine:3.4 -> scratch:latest
1 alpine镜像
Dockerfile路径：https://github.com/gliderlabs/docker-alpine/blob/8f23fc2e995ab8f7f0f5960c6a1ddd12f57efd0c/versions/library-3.4/Dockerfile
Docker Registry镜像依赖于alpine:3.4镜像，alpine镜像是一个基于Alpine Linux的一个Docker镜像，它拥有完整的包索引，它真的很小，编译出来只有4.803M。
# make
sha256:8cbba14eb7fe1eb44e53557028f622d3de6baf5b932e53b4522b7b525f3c42c3
sha256:659b6da402fd38431f58614b4c57fa6c6efec87702702446c8636628f434d246
# docker images
REPOSITORY TAG IMAGE ID CREATED SIZE
haskell-scratch integer-simple 659b6da402fd seconds ago 3.811 MB
haskell-scratch integer-gmp 8cbba14eb7fe seconds ago 4.286 MB
执行成功后即可得到两个镜像，haskell-scratch:integer-simple和haskell-scratch:integer-gmp
为了使用方便，我们给scratch创建个tag，命令如下：
docker tag haskell-scratch:integer-gmp scratch
3.2 从https://codeload.github.com/gliderlabs/docker-alpine/zip/8f23fc2e995ab8f7f0f5960c6a1ddd12f57efd0c下载alpine，解压后进入docker-alpine-8f23fc2e995ab8f7f0f5960c6a1ddd12f57efd0c/versions/library-3.4目录执行build命令编译alpine镜像，命令如下：
docker build -t alpine:3.4 .
3.3 从https://codeload.github.com/docker/distribution-library-image/zip/3b4a84c1f152b60688e99d2efadf305479541482下载registry，解压后进入distribution-library-image-3b4a84c1f152b60688e99d2efadf305479541482目录，执行build命令编译registry镜像，命令如下：
docker build -t registry .
至此就有了自己一步步编译出来的registry镜像，那么创建个容器试试，命令如下：
# docker run -d -p : --restart=always --name registry registry
055d53fe984679128e2ab8404a4eb4087eb0eb1713368b048d030e8d65a8f56d
# docker ps -a
CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES
055d53fe9846 registry "/entrypoint.sh /etc/" minutes ago Up minutes 0.0.0.0:->/tcp registry
3.4 push镜像至私有仓
首先，想要push镜像至私有仓，镜像名必须满足一定格式，格式为registry_host:port/image_name:tag
我们给hello-world:latest镜像创建个tag，命令如下：
# docker tag hello-world localhost:5000/hello-world
# docker images
REPOSITORY TAG IMAGE ID CREATED SIZE
hello-world latest c54a2cc56cbb 12 weeks ago 1.848 kB
localhost:5000/hello-world latest c54a2cc56cbb 12 weeks ago 1.848 kB
然后docker push就可以将这个镜像提交到私有仓中了，如下：
docker push localhost:/hello-world
The push refers to a repository [localhost:/hello-world]
a02596fdd012: Pushed
latest: digest: sha256:a18ed77532f6d6781500db650194e0f9396ba5f05f8b50d4046b294ae5f83aa4 size:
接下来为了验证我们的私有仓可用，我将本地的hello-world镜像删除后来做验证，过程如下：
root@ *** :~# docker rmi localhost:/hello-world hello-world
Untagged: localhost:/hello-world:latest
Untagged: localhost:/hello-world@sha256:a18ed77532f6d6781500db650194e0f9396ba5f05f8b50d4046b294ae5f83aa4
Untagged: hello-world:latest
Untagged: hello-world@sha256:0256e8a36e2070f7bf2d0b0763dbabdd67798512411de4cdcf9431a1feb60fd9
Deleted: sha256:c54a2cc56cbb2f04003c1cd4507e118af7c0d340fe7e2720f70976c4b75237dc
Deleted: sha256:a02596fdd012f22b03af6ad7d11fa590c57507558357b079c3e8cebceb4262d7
root@ *** :~# docker run localhost:/hello-world
Unable to find image 'localhost:5000/hello-world:latest' locally
latest: Pulling from hello-world c04b14da8d14: Pull complete
Digest: sha256:a18ed77532f6d6781500db650194e0f9396ba5f05f8b50d4046b294ae5f83aa4
Status: Downloaded newer image for localhost:/hello-world:latest Hello from Docker!
This message shows that your installation appears to be working correctly. To generate this message, Docker took the following steps:
. The Docker client contacted the Docker daemon.
. The Docker daemon pulled the "hello-world" image from the Docker Hub.
. The Docker daemon created a new container from that image which runs the
executable that produces the output you are currently reading.
. The Docker daemon streamed that output to the Docker client, which sent it
to your terminal. To try something more ambitious, you can run an Ubuntu container with:
$ docker run -it ubuntu bash Share images, automate workflows, and more with a free Docker Hub account:
https://hub.docker.com For more examples and ideas, visit:
https://docs.docker.com/engine/userguide/
至此，私有仓搭建成功。