第七篇：Docker镜像操作

运行容器时，当本地不存在镜像时，docker 就会自动从 docker 镜像仓库中下载，默认是从 Docker Hub 公共镜像源下载。

1.列出本地镜像

[root@docker ~]# docker images
REPOSITORY          TAG                 IMAGE ID            CREATED             SIZE
httpd               latest              2e202f453940        11 days ago         179MB
nginx               latest              3f8a4339aadd        5 weeks ago         108MB
hello-world         latest              f2a91732366c        2 months ago        1.85kB
training/webapp     latest              6fae60ef3446        2 years ago         349MB

参数说明：

REPOSITORY：表示镜像的仓库源
TAG：镜像的标签
IMAGE ID：镜像ID
CREATED：镜像创建时间
SIZE：镜像大小

2.使用镜像运行容器

[root@docker ~]# docker run -ti httpd /bin/bash
root@dd34d7458e86:/usr/local/apache2# ls
bin  build  cgi-bin  conf  error  htdocs  icons  include  logs  modules
root@dd34d7458e86:/usr/local/apache2#

3.拉取新镜像

如果本地不存在使用的镜像，Docker就会自动到镜像仓库去下载镜像,使用docker pull

[root@docker ~]# docker pull ubuntu:16.04   ##下载指定版本镜像
16.04: Pulling from library/ubuntu
1be7f2b886e8: Pull complete
6fbc4a21b806: Pull complete
c71a6f8e1378: Pull complete
4be3072e5a37: Pull complete
06c6d2f59700: Pull complete
Digest: sha256:2b80e7fbfd1b0a3784dd0e55fb6f2750ebc33e596c2ccee5201ecf018ac5ae05
Status: Downloaded newer image for ubuntu:16.04

4.搜索镜像

可以通过docker search 命令搜索需要使用的镜像

[root@docker ~]# docker search httpd
NAME                                DESCRIPTION                                     STARS               OFFICIAL            AUTOMATED
httpd                               The Apache HTTP Server Project                  1490                [OK]
hypriot/rpi-busybox-httpd           Raspberry Pi compatible Docker Image with a …   40
centos/httpd                                                                        15                                      [OK]
centos/httpd-24-centos7             Platform for running Apache httpd 2.4 or bui…   8
armhf/httpd                         The Apache HTTP Server Project                  8
macadmins/netboot-httpd             use in combination with bruienne/bsdpy          4                                       [OK]
salim1983hoop/httpd24               Dockerfile running apache config                2                                       [OK]
lolhens/httpd                       Apache httpd 2 Server                           2                                       [OK]
rgielen/httpd-image-php5            Docker image for Apache httpd with PHP 5 bas…   1                                       [OK]
rgielen/httpd-image-simple          Docker image for simple Apache httpd based o…   1                                       [OK]
lead4good/httpd-fpm                 httpd server which connects via fcgi proxy h…   1                                       [OK]
fboaventura/dckr-httpd              Small footprint http server to use with othe…   1                                       [OK]
epflidevelop/os-wp-httpd            WP httpd                                        1                                       [OK]
publici/httpd                       httpd:latest                                    0                                       [OK]
tplatform/aws-linux-httpd24-php70   aws-linux-httpd24-php70                         0                                       [OK]
dockerpinata/httpd                                                                  0

5.创建镜像

在生产环境上，一般情况下，docker镜像需要自身业务来定制，可通过两种方式来实现docker镜像的定制化
a.从已有创建的容器镜像更新
b.根据自身需求编写dockerfile创建新镜像

更新镜像前，先使用该镜像创建一个容器

[root@docker ~]# docker images
REPOSITORY          TAG                 IMAGE ID            CREATED             SIZE
httpd               latest              2e202f453940        11 days ago         179MB
ubuntu              16.04               0458a4468cbc        11 days ago         112MB
nginx               latest              3f8a4339aadd        5 weeks ago         108MB
hello-world         latest              f2a91732366c        2 months ago        1.85kB
training/webapp     latest              6fae60ef3446        2 years ago         349MB
[root@docker ~]# docker run -ti ubuntu:16.04 /bin/bash
root@7e0559072ced:/#

进入镜像使用apt-get update 命令更新

[root@docker ~]# docker exec -ti 7e0559072ced bash
root@7e0559072ced:/# apt-get update
Get:1 http://archive.ubuntu.com/ubuntu xenial InRelease [247 kB]
Get:2 http://security.ubuntu.com/ubuntu xenial-security InRelease [102 kB]
Get:3 http://security.ubuntu.com/ubuntu xenial-security/universe Sources [58.3 kB]
Get:4 http://archive.ubuntu.com/ubuntu xenial-updates InRelease [102 kB]
Get:5 http://security.ubuntu.com/ubuntu xenial-security/main amd64 Packages [553 kB]
Get:6 http://archive.ubuntu.com/ubuntu xenial-backports InRelease [102 kB]
Get:7 http://archive.ubuntu.com/ubuntu xenial/universe Sources [9802 kB]
Get:8 http://security.ubuntu.com/ubuntu xenial-security/restricted amd64 Packages [12.7 kB]
Get:9 http://security.ubuntu.com/ubuntu xenial-security/universe amd64 Packages [253 kB]
Get:10 http://security.ubuntu.com/ubuntu xenial-security/multiverse amd64 Packages [3486 B]
Get:11 http://archive.ubuntu.com/ubuntu xenial/main amd64 Packages [1558 kB]
Get:12 http://archive.ubuntu.com/ubuntu xenial/restricted amd64 Packages [14.1 kB]
Get:13 http://archive.ubuntu.com/ubuntu xenial/universe amd64 Packages [9827 kB]
Get:14 http://archive.ubuntu.com/ubuntu xenial/multiverse amd64 Packages [176 kB]
Get:15 http://archive.ubuntu.com/ubuntu xenial-updates/universe Sources [239 kB]
Get:16 http://archive.ubuntu.com/ubuntu xenial-updates/main amd64 Packages [922 kB]
Get:17 http://archive.ubuntu.com/ubuntu xenial-updates/restricted amd64 Packages [13.1 kB]
Get:18 http://archive.ubuntu.com/ubuntu xenial-updates/universe amd64 Packages [747 kB]
Get:19 http://archive.ubuntu.com/ubuntu xenial-updates/multiverse amd64 Packages [18.5 kB]
Get:20 http://archive.ubuntu.com/ubuntu xenial-backports/main amd64 Packages [5162 B]
Get:21 http://archive.ubuntu.com/ubuntu xenial-backports/universe amd64 Packages [7179 B]
Fetched 24.8 MB in 32s (772 kB/s)
Reading package lists... Done

root@7e0559072ced:/# exit
exit
[root@docker ~]# docker ps |grep ubuntu
7e0559072ced        ubuntu:16.04        "/bin/bash"         9 hours ago         Up 9 hours                                    naughty_jennings

说明：

此时ubuntu的容器ID：7e0559072ced，可以通过docker commit来提交容器副本

[root@docker ~]# docker commit -m="has update" -a="liu" 7e0559072ced liu/ubuntu:v2
sha256:15caed78232629df1ec5cd077d38215271bc413d12bc1500dc52cb3bc3e12c75

-m:提交的描述信息

-a:指定镜像作者

7e0559072ced:容器的ID

liu/ubuntu:v2指定要创建的目标镜像名

使用docker images查看提交的新镜像

[root@docker ~]# docker images
REPOSITORY          TAG                 IMAGE ID            CREATED             SIZE
liu/ubuntu          v2                  15caed782326        2 minutes ago       151MB    ####提交的新镜像
httpd               latest              2e202f453940        11 days ago         179MB
ubuntu              16.04               0458a4468cbc        12 days ago         112MB
nginx               latest              3f8a4339aadd        6 weeks ago         108MB
hello-world         latest              f2a91732366c        2 months ago        1.85kB
training/webapp     latest              6fae60ef3446        2 years ago         349MB

使用新镜像启动一个容器

[root@docker ~]# docker run -ti liu/ubuntu:v2 /bin/bash
root@60e40fc5e5d8:/#

6.构建镜像

使用docker build 从零开始构建一个新的镜像，需要编写Dockerfile容器文件，如

[root@docker ~]# vim Dockerfile

FROM    centos:6.7
##指定使用哪个镜像源
MAINTAINER      Fisher "fisher@sudops.com"
##RUN告诉docker需要在镜像内执行哪些命令
RUN     /bin/echo 'root:123456' |chpasswd
RUN     useradd liulei
RUN     /bin/echo 'liulei:123456' |chpasswd
RUN     /bin/echo -e "LANG=\"en_US.UTF-8\"" >/etc/default/local
EXPOSE  22
EXPOSE  80
CMD     /usr/sbin/sshd -D
~
~

在编写Dockerfile文件时，每一个指令都会在镜像上创建一个新的层，并且每一条指令首字母必须是大写

然后，使用编写的Dockerfile文件，通过docker build命令来构建一个镜像

[root@docker ~]# docker build -t liulei/centos:6.7 .
ERRO[0000] Can't add file /root/.gnupg/S.gpg-agent to tar: archive/tar: sockets not supported
Sending build context to Docker daemon  779.4MB
Step 1/9 : FROM    centos:6.7
6.7: Pulling from library/centos
cbddbc0189a0: Pull complete
Digest: sha256:7248c96de4648749c7936f203d983530e7ebdd83c3db6d47278392f18bcd7baf
Status: Downloaded newer image for centos:6.7
---> 000c5746fa52
Step 2/9 : MAINTAINER      Fisher "fisher@sudops.com"
---> Running in 7de81283b6be
Removing intermediate container 7de81283b6be
---> 00e92f10a010
Step 3/9 : RUN     /bin/echo 'root:123456' |chpasswd
---> Running in e2265b58e93b
Removing intermediate container e2265b58e93b
---> 0bd4ee58d0e3
Step 4/9 : RUN     useradd liulei
---> Running in 846595d00078
Removing intermediate container 846595d00078
---> 600139a37c32
Step 5/9 : RUN     /bin/echo 'liulei:123456' |chpasswd
---> Running in 236b3202305b
Removing intermediate container 236b3202305b
---> 984723c05b0f
Step 6/9 : RUN     /bin/echo -e "LANG=\"en_US.UTF-8\"" >/etc/default/local
---> Running in c18bf04cfb8c
Removing intermediate container c18bf04cfb8c
---> 65c9fe71b1f9
Step 7/9 : EXPOSE  22
---> Running in 93f0491bde21
Removing intermediate container 93f0491bde21
---> 14ee40f132fc
Step 8/9 : EXPOSE  80
---> Running in 5be75fdead2e
Removing intermediate container 5be75fdead2e
---> f380dde783ad
Step 9/9 : CMD     /usr/sbin/sshd -D
---> Running in cf4e114e9953
Removing intermediate container cf4e114e9953
---> dc64de0c25c4
Successfully built dc64de0c25c4
Successfully tagged liulei/centos:6.7
[root@docker ~]#

参数说明

-t 表示指定要创建的目标镜像名

. 表示Dokerfile文件在当前目录，也可以指定Dockerfile的绝对路径

使用docker images 查看通过dockerfile文件创建的镜像是否存在

[root@docker ~]# docker images
REPOSITORY          TAG                 IMAGE ID            CREATED             SIZE
liulei/centos       6.7                 dc64de0c25c4        6 minutes ago       191MB      ##使用Dockerfile创建的镜像
liu/ubuntu          v2                  15caed782326        21 minutes ago      151MB
httpd               latest              2e202f453940        11 days ago         179MB
ubuntu              16.04               0458a4468cbc        12 days ago         112MB
nginx               latest              3f8a4339aadd        6 weeks ago         108MB
hello-world         latest              f2a91732366c        2 months ago        1.85kB
centos              6.7                 000c5746fa52        3 months ago        191MB
training/webapp     latest              6fae60ef3446        2 years ago         349MB

使用Dockerfile文件创建的镜像来运行容器

[root@docker ~]# docker run -ti dc64de0c25c4 /bin/bash
[root@c12f3fe4ea60 /]#

7.设置镜像标签

使用docker tag 命令为镜像设置标签

[root@docker ~]# docker tag dc64de0c25c4 liulei/centos:new
[root@docker ~]# docker images
REPOSITORY          TAG                 IMAGE ID            CREATED             SIZE
liulei/centos       6.7                 dc64de0c25c4        13 minutes ago      191MB
liulei/centos       new                 dc64de0c25c4        13 minutes ago      191MB
liu/ubuntu          v2                  15caed782326        28 minutes ago      151MB
httpd               latest              2e202f453940        11 days ago         179MB
ubuntu              16.04               0458a4468cbc        12 days ago         112MB
nginx               latest              3f8a4339aadd        6 weeks ago         108MB
hello-world         latest              f2a91732366c        2 months ago        1.85kB
centos              6.7                 000c5746fa52        3 months ago        191MB
training/webapp     latest              6fae60ef3446        2 years ago         349MB