镜像是Docker的三大核心概念之一。Docker在运行容器之前，本地需要存有镜像，若不存在则Docker会首先尝试从默认的镜像仓库中去下载，当然我们也可以去配置自己的仓库，如此就会从我们配置的仓库中去下载。
一、获取镜像
镜像是Docker运行容器的前提条件，我们可以通过 docker pull 命令来下载镜像，语法格式为：docker pull name[:tag]。若我们不指定具体的tag版本，则默认下载最新的版本即 latest标签的镜像。
# 1. 下载一个最新版本的 ubuntu 镜像
$ docker pull ubuntu
Using default tag: latest
latest: Pulling from library/ubuntu
5bed26d33875: Pull complete
f11b29a9c730: Pull complete
930bda195c84: Pull complete
78bf9a5ad49e: Pull complete
Digest: sha256:bec5a2727be7fff3d308193cfde3491f8fba1a2ba392b7546b43a051853a341d
Status: Downloaded newer image for ubuntu:latest
docker.io/library/ubuntu:latest
# 2. 下载一个指定的 ubuntu 镜像版本
$ sudo docker pull ubuntu:14.04
14.04: Pulling from library/ubuntu
2e6e20c8e2e6: Pull complete
30bb187ac3fc: Pull complete
b7a5bcc4a58a: Pull complete
Digest: sha256:ffc76f71dd8be8c9e222d420dc96901a07b61616689a44c7b3ef6a10b7213de4
Status: Downloaded newer image for ubuntu:14.04
docker.io/library/ubuntu:14.04
# 3. 以上两种都是从默认的Docker镜像仓库下载镜像，当然我们也可以从指定仓库下载
$ sudo docker pull dl.aliyun.com:1000/ubuntu
# 4. 镜像下载之后就可以运行了，使用镜像来创建容器
$ sudo docker run -t -i ubuntu /bin/bash
root@95e3c40a7b3b:/#
root@95e3c40a7b3b:/# ll # 这里是在容器中执行的命令
total 28
drwxr-xr-x. 21 root root 4096 Apr 5 10:30 ./
drwxr-xr-x. 21 root root 4096 Apr 5 10:30 ../
-rwxr-xr-x. 1 root root 0 Apr 5 10:30 .dockerenv*
drwxr-xr-x. 2 root root 4096 Mar 11 21:05 bin/
drwxr-xr-x. 2 root root 6 Apr 24 2018 boot/
drwxr-xr-x. 5 root root 360 Apr 5 10:30 dev/
drwxr-xr-x. 29 root root 4096 Apr 5 10:30 etc/
drwxr-xr-x. 2 root root 6 Apr 24 2018 home/
drwxr-xr-x. 8 root root 96 May 23 2017 lib/
drwxr-xr-x. 2 root root 34 Mar 11 21:03 lib64/
drwxr-xr-x. 2 root root 6 Mar 11 21:03 media/
drwxr-xr-x. 2 root root 6 Mar 11 21:03 mnt/
drwxr-xr-x. 2 root root 6 Mar 11 21:03 opt/
dr-xr-xr-x. 388 root root 0 Apr 5 10:30 proc/
drwx------. 2 root root 37 Mar 11 21:05 root/
drwxr-xr-x. 5 root root 58 Mar 20 19:20 run/
drwxr-xr-x. 2 root root 4096 Mar 20 19:20 sbin/
drwxr-xr-x. 2 root root 6 Mar 11 21:03 srv/
dr-xr-xr-x. 13 root root 0 Apr 11 2018 sys/
drwxrwxrwt. 2 root root 6 Mar 11 21:05 tmp/
drwxr-xr-x. 10 root root 4096 Mar 11 21:03 usr/
drwxr-xr-x. 11 root root 4096 Mar 11 21:05 var/
二、查看镜像信息
我们可以使用 docker images 命令来列出本地主机上已有的镜像。
# 1. 列出本机上都有哪些镜像
$ sudo docker images
REPOSITORY TAG IMAGE ID CREATED SIZE
ubuntu latest 4e5021d210f6 2 weeks ago 64.2MB
ubuntu 14.04 6e4f1fe62ff1 3 months ago 196MB
# 说明：从上面我们可以看到，在第一节我们下载的镜像都在本机中
# REPOSITORY 来自于哪个仓库
# TAG 镜像的标签信息
# IMAGE ID 镜像的ID号，这是唯一的
# CREATED 镜像的创建时间
# SIZE 镜像大小
除了从仓库下载的镜像文件，我们也可以对已有的本地镜像进行重新打标签，来适应自己项目命名。
# 将 ubuntu:latest 镜像打上自己的 ubuntu 镜像
$ sudo docker tag 192.168.0.128:5000/ubuntu:latest ubuntu:latest
$ sudo docker images
REPOSITORY TAG IMAGE ID CREATED SIZE
ubuntu 14.04 4e5021d210f6 2 weeks ago 64.2MB
192.168.0.128:5000/ubuntu latest 6e4f1fe62ff1 3 months ago 196MB
ubuntu latest 6e4f1fe62ff1 3 months ago 196MB
我们查看以上的三个本地镜像，其中有两个镜像的ID是相同的，这说明这两个镜像指向的是同一个镜像文件，只是它们有着不同的别名。
# 查看某一个镜像的详细信息
$ sudo docker inspect 6e4f1fe62ff1(镜像ID)
[
{
"Id": "sha256:6e4f1fe62ff14a4c8119781d47a3739fa97c190e1df38e868794ad7a7cf50a48",
"RepoTags": [
"ubuntu:14.04",
"ubuntu:latest"
],
"RepoDigests": [
"ubuntu@sha256:ffc76f71dd8be8c9e222d420dc96901a07b61616689a44c7b3ef6a10b7213de4"
],
"Parent": "",
"Comment": "",
"Created": "2019-12-19T04:23:45.705096855Z",
"Container": "accd5cd52ef3ece3d4115e456824c3a37749ec10de75c3ad187b74c518b7890a",
"ContainerConfig": {
"Hostname": "accd5cd52ef3",
"Domainname": "",
"User": "",
"AttachStdin": false,
"AttachStdout": false,
"AttachStderr": false,
"Tty": false,
"OpenStdin": false,
"StdinOnce": false,
"Env": [
"PATH=/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin"
],
"Cmd": [
"/bin/sh",
"-c",
"#(nop) ",
"CMD ["/bin/bash"]"
],
"ArgsEscaped": true,
"Image": "sha256:f23179da08e323ef4bef58a9425152eb39ed802c1b6f8f597113c9fe950e0b24",
"Volumes": null,
"WorkingDir": "",
"Entrypoint": null,
"OnBuild": null,
"Labels": {}
},
"DockerVersion": "18.06.1-ce",
"Author": "",
"Config": {
"Hostname": "",
"Domainname": "",
"User": "",
"AttachStdin": false,
"AttachStdout": false,
"AttachStderr": false,
"Tty": false,
"OpenStdin": false,
"StdinOnce": false,
"Env": [
"PATH=/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin"
],
"Cmd": [
"/bin/bash"
],
"ArgsEscaped": true,
"Image": "sha256:f23179da08e323ef4bef58a9425152eb39ed802c1b6f8f597113c9fe950e0b24",
"Volumes": null,
"WorkingDir": "",
"Entrypoint": null,
"OnBuild": null,
"Labels": null
},
"Architecture": "amd64",
"Os": "linux",
"Size": 196466523,
"VirtualSize": 196466523,
"GraphDriver": {
"Data": {
"DeviceId": "8",
"DeviceName": "docker-253:0-67518837-e6323ccccc77b0b03785b672a7de35dd14baa660562dd07f7e9889041c905868",
"DeviceSize": "10737418240"
},
"Name": "devicemapper"
},
"RootFS": {
"Type": "layers",
"Layers": [
"sha256:f2fa9f4cf8fd0a521d40e34492b522cee3f35004047e617c75fadeb8bfd1e6b7",
"sha256:48dc77435ad5c63ea60d91e6ad4828c70e7e61755f99982b0505abb8aaa00872",
"sha256:3da511183950aa462f667f43fcda0bb5484c5c73eaa94fcd0a94bbd4db396e1c"
]
},
"Metadata": {
"LastTagTime": "2020-04-05T18:42:30.861232446+08:00"
}
}
]
# 查看具体某个参数
$ sudo docker inspect -f {{".Architecture"}} 6e4(镜像ID,可以只使用前面几个字母会自动定位)
amd64
三、搜索镜像
若我们不确定仓库是否有我们需要版本的镜像，我们也可以使用 docker search 命令先搜寻一下。语法为 docker search TERM，其中包含以下参数：
--automated=false 仅显示自动创建的镜像
--no-trunc=false 输出信息不截断显示
-s，--stars=0 指定仅显示评价为指定星级以上的镜像
# 以搜寻 MySQL 镜像为例
$ sudo docker search mysql
NAME DESCRIPTION STARS OFFICIAL AUTOMATED
mysql MySQL is a widely used, open-source relation… 9335 [OK]
mariadb MariaDB is a community-developed fork of MyS… 3347 [OK]
mysql/mysql-server Optimized MySQL Server Docker images. Create… 683 [OK]
centos/mysql-57-centos7 MySQL 5.7 SQL database server 74
mysql/mysql-cluster Experimental MySQL Cluster Docker images. Cr… 66
centurylink/mysql Image containing mysql. Optimized to be link… 61 [OK]
deitch/mysql-backup REPLACED! Please use http://hub.docker.com/r… 41 [OK]
bitnami/mysql Bitnami MySQL Docker Image 37 [OK]
tutum/mysql Base docker image to run a MySQL database se… 34
schickling/mysql-backup-s3 Backup MySQL to S3 (supports periodic backup… 29 [OK]
prom/mysqld-exporter 27 [OK]
linuxserver/mysql A Mysql container, brought to you by LinuxSe… 25
centos/mysql-56-centos7 MySQL 5.6 SQL database server 19
circleci/mysql MySQL is a widely used, open-source relation… 19
mysql/mysql-router MySQL Router provides transparent routing be… 15
databack/mysql-backup Back up mysql databases to... anywhere! 14
arey/mysql-client Run a MySQL client from a docker container 13 [OK]
openshift/mysql-55-centos7 DEPRECATED: A Centos7 based MySQL v5.5 image… 6
genschsa/mysql-employees MySQL Employee Sample Database 5 [OK]
fradelg/mysql-cron-backup MySQL/MariaDB database backup using cron tas… 5 [OK]
devilbox/mysql Retagged MySQL, MariaDB and PerconaDB offici… 2
ansibleplaybookbundle/mysql-apb An APB which deploys RHSCL MySQL 2 [OK]
jelastic/mysql An image of the MySQL database server mainta… 1
widdpim/mysql-client Dockerized MySQL Client (5.7) including Curl… 0 [OK]
monasca/mysql-init A minimal decoupled init container for mysql 0
# 仅显示自动创建的 mysql 镜像
$ sudo docker search --automated=false mysql
Flag --automated has been deprecated, use --filter=is-automated=true instead
NAME DESCRIPTION STARS OFFICIAL AUTOMATED
mysql MySQL is a widely used, open-source relation… 9335 [OK]
mariadb MariaDB is a community-developed fork of MyS… 3347 [OK]
mysql/mysql-server Optimized MySQL Server Docker images. Create… 683 [OK]
centos/mysql-57-centos7 MySQL 5.7 SQL database server 74
mysql/mysql-cluster Experimental MySQL Cluster Docker images. Cr… 66
centurylink/mysql Image containing mysql. Optimized to be link… 61 [OK]
deitch/mysql-backup REPLACED! Please use http://hub.docker.com/r… 41 [OK]
bitnami/mysql Bitnami MySQL Docker Image 37 [OK]
tutum/mysql Base docker image to run a MySQL database se… 34
schickling/mysql-backup-s3 Backup MySQL to S3 (supports periodic backup… 29 [OK]
prom/mysqld-exporter 27 [OK]
linuxserver/mysql A Mysql container, brought to you by LinuxSe… 25
centos/mysql-56-centos7 MySQL 5.6 SQL database server 19
circleci/mysql MySQL is a widely used, open-source relation… 19
mysql/mysql-router MySQL Router provides transparent routing be… 15
databack/mysql-backup Back up mysql databases to... anywhere! 14
arey/mysql-client Run a MySQL client from a docker container 13 [OK]
openshift/mysql-55-centos7 DEPRECATED: A Centos7 based MySQL v5.5 image… 6
genschsa/mysql-employees MySQL Employee Sample Database 5 [OK]
fradelg/mysql-cron-backup MySQL/MariaDB database backup using cron tas… 5 [OK]
devilbox/mysql Retagged MySQL, MariaDB and PerconaDB offici… 2
ansibleplaybookbundle/mysql-apb An APB which deploys RHSCL MySQL 2 [OK]
jelastic/mysql An image of the MySQL database server mainta… 1
widdpim/mysql-client Dockerized MySQL Client (5.7) including Curl… 0 [OK]
monasca/mysql-init A minimal decoupled init container for mysql 0
# 不截断显示镜像
$ sudo docker search --no-trunc=false mysql
NAME DESCRIPTION STARS OFFICIAL AUTOMATED
mysql MySQL is a widely used, open-source relation… 9335 [OK]
mariadb MariaDB is a community-developed fork of MyS… 3347 [OK]
mysql/mysql-server Optimized MySQL Server Docker images. Create… 683 [OK]
centos/mysql-57-centos7 MySQL 5.7 SQL database server 74
mysql/mysql-cluster Experimental MySQL Cluster Docker images. Cr… 66
centurylink/mysql Image containing mysql. Optimized to be link… 61 [OK]
deitch/mysql-backup REPLACED! Please use http://hub.docker.com/r… 41 [OK]
bitnami/mysql Bitnami MySQL Docker Image 37 [OK]
tutum/mysql Base docker image to run a MySQL database se… 34
schickling/mysql-backup-s3 Backup MySQL to S3 (supports periodic backup… 29 [OK]
prom/mysqld-exporter 27 [OK]
linuxserver/mysql A Mysql container, brought to you by LinuxSe… 25
centos/mysql-56-centos7 MySQL 5.6 SQL database server 19
circleci/mysql MySQL is a widely used, open-source relation… 19
mysql/mysql-router MySQL Router provides transparent routing be… 15
databack/mysql-backup Back up mysql databases to... anywhere! 14
arey/mysql-client Run a MySQL client from a docker container 13 [OK]
openshift/mysql-55-centos7 DEPRECATED: A Centos7 based MySQL v5.5 image… 6
genschsa/mysql-employees MySQL Employee Sample Database 5 [OK]
fradelg/mysql-cron-backup MySQL/MariaDB database backup using cron tas… 5 [OK]
devilbox/mysql Retagged MySQL, MariaDB and PerconaDB offici… 2
ansibleplaybookbundle/mysql-apb An APB which deploys RHSCL MySQL 2 [OK]
jelastic/mysql An image of the MySQL database server mainta… 1
widdpim/mysql-client Dockerized MySQL Client (5.7) including Curl… 0 [OK]
monasca/mysql-init A minimal decoupled init container for mysql 0
# 显示 stars 大于10 的镜像
$ sudo docker search -s=10 mysql
Flag --stars has been deprecated, use --filter=stars=3 instead
NAME DESCRIPTION STARS OFFICIAL AUTOMATED
mysql MySQL is a widely used, open-source relation… 9335 [OK]
mariadb MariaDB is a community-developed fork of MyS… 3347 [OK]
mysql/mysql-server Optimized MySQL Server Docker images. Create… 683 [OK]
centos/mysql-57-centos7 MySQL 5.7 SQL database server 74
mysql/mysql-cluster Experimental MySQL Cluster Docker images. Cr… 66
centurylink/mysql Image containing mysql. Optimized to be link… 61 [OK]
deitch/mysql-backup REPLACED! Please use http://hub.docker.com/r… 41 [OK]
bitnami/mysql Bitnami MySQL Docker Image 37 [OK]
tutum/mysql Base docker image to run a MySQL database se… 34
schickling/mysql-backup-s3 Backup MySQL to S3 (supports periodic backup… 29 [OK]
prom/mysqld-exporter 27 [OK]
linuxserver/mysql A Mysql container, brought to you by LinuxSe… 25
centos/mysql-56-centos7 MySQL 5.6 SQL database server 19
circleci/mysql MySQL is a widely used, open-source relation… 19
mysql/mysql-router MySQL Router provides transparent routing be… 15
databack/mysql-backup Back up mysql databases to... anywhere! 14
arey/mysql-client Run a MySQL client from a docker container 13 [OK]
四、删除镜像
对于不需要的镜像我们可以将其删除，删除镜像语法为：docker rmi IMAGE[IMAGE...]
# 删除一个镜像
$ sudo docker images
REPOSITORY TAG IMAGE ID CREATED SIZE
ubuntu <none> 4e5021d210f6 2 weeks ago 64.2MB
ubuntu 14.04 6e4f1fe62ff1 3 months ago 196MB
ubuntu latest 6e4f1fe62ff1 3 months ago 196MB
$ sudo docker rmi ubuntu:14.04(6e4f1fe62ff1)
# 可为标签或ID删除，需要注意若指定镜像ID删除，则所有的指向该镜像的标签也都删除,此时需要强制删除才可否则删除失败
Error response from daemon: conflict: unable to delete 6e4f1fe62ff1 (must be forced) - image is referenced in multiple repositories
$ sudo docker rmi -f 6e4f1fe62ff1
Untagged: ubuntu:14.04
Untagged: ubuntu:latest
Untagged: ubuntu@sha256:ffc76f71dd8be8c9e222d420dc96901a07b61616689a44c7b3ef6a10b7213de4
Deleted: sha256:6e4f1fe62ff14a4c8119781d47a3739fa97c190e1df38e868794ad7a7cf50a48
Deleted: sha256:bf1b2d677f21703e5be92de8b094fbf5cceeea666885053b40b8a5b2f20638b3
Deleted: sha256:9b22c82c6d5a884491639891b0eb053e6e58d6da35ad2d73655d7dd2707d6d73
Deleted: sha256:f2fa9f4cf8fd0a521d40e34492b522cee3f35004047e617c75fadeb8bfd1e6b7
$ sudo docker images
REPOSITORY TAG IMAGE ID CREATED SIZE
ubuntu <none> 4e5021d210f6 2 weeks ago 64.2MB
在删除镜像之前，我们建议先查看该镜像是否有一个容器在引用，还有尽量不要使用 -f 强制删除。
# 查看本地有哪些容器
$ sudo docker ps -a
CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES
95e3c40a7b3b 4e5021d210f6 "/bin/bash" 46 minutes ago Exited (127) 43 minutes ago determined_rubin
# 说明：通过查看Docker容器，我们可知镜像4e5021d210f6被使用，在删除该镜像时就需要注意了。不要强制去删除
若我们发现该镜像以后也不在使用了，正确的做法也不是强制删除，而是先解除容器和镜像之间的依赖，再删除镜像文件。
# 0. 查看本机有哪些容器
$ sudo docker ps -a
CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES
95e3c40a7b3b 4e5021d210f6 "/bin/bash" 51 minutes ago Exited (127) 48 minutes ago determined_rubin
# 1. 删除不需要的的容器
$ sudo docker rm 95e3c40a7b3b
95e3c40a7b3b
# 2. 再查看发现容器已删除
$ sudo docker ps -a
CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES
# 3. 最后再删除不需要的镜像文件
$ sudo docker rmi 4e5021d210f6
# 4. 查看本地镜像已被删除
$ sudo docker images
REPOSITORY TAG IMAGE ID CREATED SIZE
五、创建镜像
关于创建镜像主要有三种方式：基于已有的镜像容器创建、基于本地模板导入、基于Dockerfile创建。
1、基于已有镜像的容器创建
使用 docker commit 命令，语法为：docker commit [options] container [repository[:tag]]，其中 options 参数可为：
-a，--author=“” 作者信息
-m，--message=“” 提交消息
-p，--pause=true 提交时暂停容器运行
下面我们来创建一个镜像：
# 0. 查看当前镜像
$ sudo docker images
REPOSITORY TAG IMAGE ID CREATED SIZE
ubuntu latest 4e5021d210f6 2 weeks ago 64.2MB
# 1. 启动一个已有的镜像
$ sudo docker run -ti ubuntu /bin/bash
root@56a5d871e739:/# touch test.txt # 在容器中创建一个文件，用来与当前的镜像做区分
root@56a5d871e739:/# exit # 退出当前容器
# 2. 提交，创建新的镜像
$ sudo docker commit -m "This is a new file" -a "gongziqi" 56a5d871e739 test
sha256:e5bc93985af09811230818a6905ce21b3428aebfeb6bae48f86772846b324be3
# 3. 再查看镜像
$ sudo docker images
REPOSITORY TAG IMAGE ID CREATED SIZE
test latest e5bc93985af0 26 seconds ago 64.2MB
ubuntu latest 4e5021d210f6 2 weeks ago 64.2MB
# 4. 查看这两个镜像运行的容器内容
$ sudo docker run -ti ubuntu /bin/bash
root@2ee2858e4b28:/# ll
total 28
drwxr-xr-x. 21 root root 4096 Apr 5 13:07 ./
drwxr-xr-x. 21 root root 4096 Apr 5 13:07 ../
-rwxr-xr-x. 1 root root 0 Apr 5 13:07 .dockerenv*
drwxr-xr-x. 2 root root 4096 Mar 11 21:05 bin/
drwxr-xr-x. 2 root root 6 Apr 24 2018 boot/
drwxr-xr-x. 5 root root 360 Apr 5 13:07 dev/
drwxr-xr-x. 29 root root 4096 Apr 5 13:07 etc/
drwxr-xr-x. 2 root root 6 Apr 24 2018 home/
drwxr-xr-x. 8 root root 96 May 23 2017 lib/
drwxr-xr-x. 2 root root 34 Mar 11 21:03 lib64/
drwxr-xr-x. 2 root root 6 Mar 11 21:03 media/
drwxr-xr-x. 2 root root 6 Mar 11 21:03 mnt/
drwxr-xr-x. 2 root root 6 Mar 11 21:03 opt/
dr-xr-xr-x. 395 root root 0 Apr 5 13:07 proc/
drwx------. 2 root root 37 Mar 11 21:05 root/
drwxr-xr-x. 5 root root 58 Mar 20 19:20 run/
drwxr-xr-x. 2 root root 4096 Mar 20 19:20 sbin/
drwxr-xr-x. 2 root root 6 Mar 11 21:03 srv/
dr-xr-xr-x. 13 root root 0 Apr 11 2018 sys/
drwxrwxrwt. 2 root root 6 Mar 11 21:05 tmp/
drwxr-xr-x. 10 root root 4096 Mar 11 21:03 usr/
drwxr-xr-x. 11 root root 4096 Mar 11 21:05 var/
root@2ee2858e4b28:/# exit
exit
$ sudo docker run -ti test /bin/bash
root@0e4030bfbad3:/# ll
total 28
drwxr-xr-x. 21 root root 4096 Apr 5 13:07 ./
drwxr-xr-x. 21 root root 4096 Apr 5 13:07 ../
-rwxr-xr-x. 1 root root 0 Apr 5 13:07 .dockerenv*
drwxr-xr-x. 2 root root 4096 Mar 11 21:05 bin/
drwxr-xr-x. 2 root root 6 Apr 24 2018 boot/
drwxr-xr-x. 5 root root 360 Apr 5 13:07 dev/
drwxr-xr-x. 29 root root 4096 Apr 5 13:07 etc/
drwxr-xr-x. 2 root root 6 Apr 24 2018 home/
drwxr-xr-x. 8 root root 96 May 23 2017 lib/
drwxr-xr-x. 2 root root 34 Mar 11 21:03 lib64/
drwxr-xr-x. 2 root root 6 Mar 11 21:03 media/
drwxr-xr-x. 2 root root 6 Mar 11 21:03 mnt/
drwxr-xr-x. 2 root root 6 Mar 11 21:03 opt/
dr-xr-xr-x. 395 root root 0 Apr 5 13:07 proc/
drwx------. 2 root root 58 Apr 5 13:05 root/
drwxr-xr-x. 5 root root 58 Mar 20 19:20 run/
drwxr-xr-x. 2 root root 4096 Mar 20 19:20 sbin/
drwxr-xr-x. 2 root root 6 Mar 11 21:03 srv/
dr-xr-xr-x. 13 root root 0 Apr 11 2018 sys/
-rw-r--r--. 1 root root 0 Apr 5 13:05 test.txt
drwxrwxrwt. 2 root root 6 Mar 11 21:05 tmp/
drwxr-xr-x. 10 root root 4096 Mar 11 21:03 usr/
drwxr-xr-x. 11 root root 4096 Mar 11 21:05 var/
# 观察：test镜像创建的容器中是有 test.txt 文件的
2、基于本地模板导入
可以从操作系统模板文件导入一个镜像。假设我们本地已经有了一个 ubuntu.tar.gz 文件，我们可通过以下命令来导入：
# 导入本地模板
$ sudo ll
$ sudo docker images
$ sudo cat ubuntu-16.04-x86_64.tar.gz | docker import - ubuntu:16.04
$ sudo docker images
3、基于Dockerfile创建
这种创建方式，我们后面专门用一节来介绍。
六、存出和载入镜像
关于Docker镜像的存出和载入，我们可以使用以下两个命令：docker save / docker load。
# 1. 存出镜像,将某个镜像存出(注意观察当前工作目录前后的文件变化)
# 1.1 查看镜像，和当前工作目录文件
$ sudo docker images
REPOSITORY TAG IMAGE ID CREATED SIZE
ubuntu latest 4e5021d210f6 2 weeks ago 64.2MB
$ sudo ll
总用量 242148
drwxr-xr-x. 4 root root 4096 4月 2 19:09 apache
drwxr-xr-x. 11 root root 4096 3月 29 15:24 apache-activemq-5.15.12
-rw-r--r--. 1 root root 62666908 3月 29 14:40 apache-activemq-5.15.12-bin.tar.gz
drwxr-xr-x. 8 10 143 4096 12月 13 2016 jdk1.8.0_121
-rw-r--r--. 1 root root 183246769 3月 29 15:17 jdk-8u121-linux-x64.tar.gz
-rw-r--r--. 1 root root 1208398 4月 5 21:16 ubuntu-16.04-x86_64.tar.gz
# 1.2 存出镜像,并查看当前工作目录
$ sudo docker save -o ubuntu_latest.tar ubuntu:latest
$ sudo ll
总用量 307152
drwxr-xr-x. 4 root root 4096 4月 2 19:09 apache
drwxr-xr-x. 11 root root 4096 3月 29 15:24 apache-activemq-5.15.12
-rw-r--r--. 1 root root 62666908 3月 29 14:40 apache-activemq-5.15.12-bin.tar.gz
drwxr-xr-x. 8 10 143 4096 12月 13 2016 jdk1.8.0_121
-rw-r--r--. 1 root root 183246769 3月 29 15:17 jdk-8u121-linux-x64.tar.gz
-rw-r--r--. 1 root root 1980762 4月 5 21:18 ubuntu-16.04-x86_64.tar.gz
-rw-------. 1 root root 66612224 4月 5 21:25 ubuntu_latest.tar
# 2. 载入镜像，将某个镜像载入系统
$ sudo docker load --input ubuntu_latest.tar
# 或
$ sudo docker load < ubuntu_latest.tar
Loaded image: ubuntu:latest
七、上传镜像
若我们希望将自己的镜像上传到仓库供别人使用，可使用 docker push 命令，默认上传到官方仓库。语法：docker push NAME[:TAG]
# 将我们上面的 test 镜像上传到仓库
$ sudo docker tag test:latest user/test:latest # 创建一个镜像标签
$ sudo docker push user/test:latest
# 说明：在第一次上传时，需要我们输入登录信息
