Centos環境docker的正確安裝及疑難雜症

根據官方文檔：https://docs.docker.com/install/linux/docker-ce/centos/搭建docker 
1.卸載docker舊版本：

sudo yum remove docker \
                  docker-client \
                  docker-client-latest \
                  docker-common \
                  docker-latest \
                  docker-latest-logrotate \
                  docker-logrotate \
                  docker-selinux \
                  docker-engine-selinux \
                  docker-engine\

2.安裝相關工具類：

sudo yum install -y yum-utils \
  device-mapper-persistent-data \
  lvm2

3.配置docker倉庫：

sudo yum-config-manager \
    --add-repo \
    https://download.docker.com/linux/centos/docker-ce.repo

會報如下錯誤：
Loaded plugins: fastestmirror
adding repo from: https://download.docker.com/linux/centos/docker-ce.repo
grabbing file https://download.docker.com/linux/centos/docker-ce.repo to /etc/yum.repos.d/docker-ce.repo
Could not fetch/save url https://download.docker.com/linux/centos/docker-ce.repo to file /etc/yum.repos.d/docker-ce.repo
: [Errno 14] curl#35 - "TCP connection reset by peer

這是因爲國內訪問不到docker官方鏡像的緣故 
能夠經過aliyun的源來完成：

sudo yum-config-manager --add-repo http://mirrors.aliyun.com/docker-ce/linux/centos/docker-ce.repo

出現如下內容則表示docker倉庫配置成功：
Loaded plugins: fastestmirror
adding repo from: http://mirrors.aliyun.com/docker-ce/linux/centos/docker-ce.repo
grabbing file http://mirrors.aliyun.com/docker-ce/linux/centos/docker-ce.repo to /etc/yum.repos.d/docker-ce.repo
repo saved to /etc/yum.repos.d/docker-ce.repo

4.安裝docker

sudo yum install docker-ce

出現如下異常：
Loaded plugins: fastestmirror
base
https://download-stage.docker.com/linux/centos/7/x86_64/stable/repodata/repomd.xml: [Errno 14] curl#35 - "TCP connection reset by peer"
Trying other mirror.
 One of the configured repositories failed (Docker CE Stable - x86_64),
 and yum doesn't have enough cached data to continue. At this point the only
 safe thing yum can do is fail. There are a few ways to work "fix" this:

     1. Contact the upstream for the repository and get them to fix the problem.

     2. Reconfigure the baseurl/etc. for the repository, to point to a working
        upstream. This is most often useful if you are using a newer
        distribution release than is supported by the repository (and the
        packages for the previous distribution release still work).

     3. Run the command with the repository temporarily disabled
            yum --disablerepo=docker-ce-stable ...

     4. Disable the repository permanently, so yum won't use it by default. Yum
        will then just ignore the repository until you permanently enable it
        again or use --enablerepo for temporary usage:

            yum-config-manager --disable docker-ce-stable
        or
            subscription-manager repos --disable=docker-ce-stable

     5. Configure the failing repository to be skipped, if it is unavailable.
        Note that yum will try to contact the repo. when it runs most commands,
        so will have to try and fail each time (and thus. yum will be be much
        slower). If it is a very temporary problem though, this is often a nice
        compromise:

            yum-config-manager --save --setopt=docker-ce-stable.skip_if_unavailable=true

failure: repodata/repomd.xml from docker-ce-stable: [Errno 256] No more mirrors to try.
https://download-stage.docker.com/linux/centos/7/x86_64/stable/repodata/repomd.xml: [Errno 14] curl#35 - "TCP connection reset by peer"

分析緣由爲：阿里的鏡像庫文件也指向docker官方庫，因此須要修改庫文件

sudo vim /etc/yum.repos.d/docker-ce.repo

經過命令把https://download-stage.docker.com替換爲http://mirrors.aliyun.com/docker-ce

命令以下：:%s#https://download-stage.docker.com#http://mirrors.aliyun.com/docker-ce#g

再執行docker的安裝命令便可安裝成功。

sudo yum install docker-ce

內容以下：

Installed:
  docker-ce.x86_64 0:18.03.0.ce-1.el7.centos

Dependency Installed:
  audit-libs-python.x86_64 0:2.7.6-3.el7 checkpolicy.x86_64 0:2.5-4.el7   container-selinux.noarch 2:2.42-1.gitad8f0f7.el7 libcgroup.x86_64 0
  libtool-ltdl.x86_64 0:2.4.2-22.el7_3   pigz.x86_64 0:2.3.3-1.el7.centos policycoreutils-python.x86_64 0:2.5-17.1.el7     python-IPy.noarch

Complete!

5.驗證docker安裝成功：

啓動docker：

sudo systemctl start docker

驗證docker:

sudo docker run hello-world

則會出現如下異常：

Unable to find image 'hello-world:latest' locally
latest: Pulling from library/hello-world
9bb5a5d4561a: Pulling fs layer
docker: error pulling image configuration: Get https://dseasb33srnrn.cloudfront.net/registry-v2/docker/registry/v2/blobs/sha256/e3/e38bc07ac18e
See 'docker run --help'.

此錯誤也是網絡問題：出現這個問題緣由爲國內網絡問題，沒法鏈接到 docker hub。 
配置阿里雲的docker鏡像庫：在阿里雲開通容器鏡像服務拿到加速地址在執行如下命令：

也能夠：

好在國內已經有  daocloud，docker指定該源便可。

vi /usr/lib/systemd/system/docker.service
[Unit]
Description=Docker Application Container Engine
Documentation=https://docs.docker.com
After=network-online.target firewalld.service
Wants=network-online.target

[Service]
Type=notify
# the default is not to use systemd for cgroups because the delegate issues still
# exists and systemd currently does not support the cgroup feature set required
# for containers run by docker
ExecStart=/usr/bin/dockerd --registry-mirror=http://f2d6cb40.m.daocloud.io
ExecReload=/bin/kill -s HUP $MAINPID
# Having non-zero Limit*s causes performance problems due to accounting overhead
# in the kernel. We recommend using cgroups to do container-local accounting.
LimitNOFILE=infinity
LimitNPROC=infinity
LimitCORE=infinity
# Uncomment TasksMax if your systemd version supports it.
# Only systemd 226 and above support this version.
#TasksMax=infinity
TimeoutStartSec=0
# set delegate yes so that systemd does not reset the cgroups of docker containers
Delegate=yes
# kill only the docker process, not all processes in the cgroup
KillMode=process
# restart the docker process if it exits prematurely
Restart=on-failure
StartLimitBurst=3
StartLimitInterval=60s

[Install]
WantedBy=multi-user.target

重啓docker服務：

$ sudo systemctl daemon-reload
$ sudo systemctl restart docker

 

再次驗證docker:

sudo docker run hello-world

出現一下內容表示驗證成功：

Unable to find image 'hello-world:latest' locally
latest: Pulling from library/hello-world
9bb5a5d4561a: Pull complete 
Digest: sha256:f5233545e43561214ca4891fd1157e1c3c563316ed8e237750d59bde73361e77
Status: Downloaded newer image for 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:
 1. The Docker client contacted the Docker daemon.
 2. The Docker daemon pulled the "hello-world" image from the Docker Hub.
    (amd64)
 3. The Docker daemon created a new container from that image which runs the
    executable that produces the output you are currently reading.
 4. 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 ID:
 https://hub.docker.com/

For more examples and ideas, visit:
 https://docs.docker.com/engine/userguide/