2.11. Docker mirroring usage

When running the container, if the image used does not exist locally, docker is automatically downloaded from the docker image repository. By default, it is downloaded from the Docker Hub public image source.

Let’s learn:

1、管理和使用本地 Docker 主机镜像
2、创建镜像

2.11.1. List a list of images ¶

We can use it. docker images To list the images on the local host.

runoob@runoob:~$ docker images REPOSITORY TAG IMAGE ID CREATED SIZE ubuntu 14.04 90d5884b1ee0 5 days ago 188 MB php 5.6 f40e9e0f10c8 9 days ago 444.8 MB nginx latest 6f8d099c3adc 12 days ago 182.7 MB mysql 5.6 f2e8d6c772c0 3 weeks ago 324.6 MB httpd latest 02ef73cf1bc0 3 weeks ago 194.4 MB ubuntu 15.10 4e3b13c8a266 4 weeks ago 136.3 MB hello-world latest 690ed74de00f 6 months ago 960 B training/webapp latest 6fae60ef3446 11 months ago 348.8 MB 

Description of each option:

REPOSITORY： Represents the warehouse source of the image
TAG： Mirrored label
IMAGE ID： Mirror ID
CREATED： Mirror creation time
SIZE： Mirror Siz

There can be multiple TAG in the same warehouse source, which represents different versions of the warehouse source. For example, there are different versions such as 15.10,14.04 in the ubuntu repository source. We use REPOSITORY:TAG to define different images.

所以，我们如果要使用版本为15.10的ubuntu系统镜像来运行容器时，命令如下：

runoob@runoob:~$ docker run -t -i ubuntu:15.10 /bin/bash root@d77ccb2e5cca:/#

Parameter description:

-i Interactive operation
-t Terminal.
ubuntu:15.10 This refers to starting the container based on the ubuntu version 15.10 image.
/bin/bash Put after the image name is the command, here we want to have an interactive Shell, so we use / bin/bash.

If you want to use the ubuntu system image with version 14.04 to run the container, the command is as follows:

runoob@runoob:~$ docker run -t -i ubuntu:14.04 /bin/bash root@39e968165990:/#

If you do not specify a version tag for the image, for example, if you only use ubuntu,docker, the ubuntu:latest image will be used by default.

2.11.2. Get a new image ¶

Docker automatically downloads the image when we use a non-existent image on the local host. If we want to download the image in advance, we can use the docker pull command to download it.

Crunoob@runoob:~$ docker pull ubuntu:13.10 13.10: Pulling from library/ubuntu 6599cadaf950: Pull complete 23eda618d451: Pull complete f0be3084efe9: Pull complete 52de432f084b: Pull complete a3ed95caeb02: Pull complete Digest: sha256:15b79a6654811c8d992ebacdfbd5152fcf3d165e374e264076aa435214a947a3 Status: Downloaded newer image for ubuntu:13.10 

After the download is complete, we can directly use this image to run the container.

2.11.3. Find Mirror ¶

We can search for images from Docker Hub. The Docker Hub address is: https://hub.docker.com/

We can also use the docker search command to search for images. For example, we need an image of httpd as our web service. We can search httpd with the docker search command to find the right image for us.

runoob@runoob:~$ docker search httpd

Click on the picture to see the larger picture:

` <../wp-content/uploads/2016/05/423F2A2C-287A-4B03-855E-6A78E125B346.jpg>` __

NAME: Name of the image warehouse source

DESCRIPTION: Description of the mirror image

OFFICIAL: Is it officially released by docker

stars: Similar to star in Github, it means to like and like it.

AUTOMATED: Build automatically.

2.11.4. Drag the mirror image ¶

We decided to use the image of the official version of httpd in the image above and use the command docker pull to download the image.

runoob@runoob:~$ docker pull httpd Using default tag: latest latest: Pulling from library/httpd 8b87079b7a06: Pulling fs layer a3ed95caeb02: Download complete 0d62ec9c6a76: Download complete a329d50397b9: Download complete ea7c1f032b5c: Waiting be44112b72c7: Waiting 

After the download is complete, we can use this image.

runoob@runoob:~$ docker run httpd

2.11.5. Delete Mirror ¶

Use of mirror deletion docker rmi Command, for example, we delete the hello-world image:

$ docker rmi hello-world

2.11.6. Create a mirror ¶

When the image we downloaded from the docker image repository does not meet our needs, we can change the image in the following two ways.

1、从已经创建的容器中更新镜像，并且提交这个镜像
2、使用 Dockerfile 指令来创建一个新的镜像

Update Mirror ¶

Before updating the image, we need to use the image to create a container.

runoob@runoob:~$ docker run -t -i ubuntu:15.10 /bin/bash root@e218edb10161:/#

Use in the running container apt-get update Command to update.

After completing the operation, type the exit command to exit the container.

At this point, ID is the container of e218edb10161, which is changed according to our requirements. We can submit a copy of the container by commanding docker commit.

runoob@runoob:~$ docker commit -m="has update" -a="runoob" e218edb10161 runoob/ubuntu:v2 sha256:70bf1840fd7c0d2d8ef0a42a817eb29f854c1af8f7c59fc03ac7bdee9545aff8 

Description of each parameter:

-m: Submitted description information
-a: Specify the mirror author
e218edb10161： Container ID
runoob/ubuntu:v2: Specify the name of the target image to create

We can use it. docker images Command to view our new image runoob/ubuntu:v2 :

runoob@runoob:~$ docker images REPOSITORY TAG IMAGE ID CREATED SIZE runoob/ubuntu v2 70bf1840fd7c 15 seconds ago 158.5 MB ubuntu 14.04 90d5884b1ee0 5 days ago 188 MB php 5.6 f40e9e0f10c8 9 days ago 444.8 MB nginx latest 6f8d099c3adc 12 days ago 182.7 MB mysql 5.6 f2e8d6c772c0 3 weeks ago 324.6 MB httpd latest 02ef73cf1bc0 3 weeks ago 194.4 MB ubuntu 15.10 4e3b13c8a266 4 weeks ago 136.3 MB hello-world latest 690ed74de00f 6 months ago 960 B training/webapp latest 6fae60ef3446 12 months ago 348.8 MB 

Use our new mirror image runoob/ubuntu To start a container.

runoob@runoob:~$ docker run -t -i runoob/ubuntu:v2 /bin/bash root@1a9fbdeb5da3:/# 

Build an image ¶

We use orders. docker build To create a new mirror from scratch To do this, we need to create a Dockerfile file that contains a set of instructions to tell Docker how to build our image.

runoob@runoob:~$ cat Dockerfile FROM centos:6.7 MAINTAINER Fisher "fisher@sudops.com" RUN /bin/echo 'root:123456' |chpasswd RUN useradd runoob RUN /bin/echo 'runoob:123456' |chpasswd RUN /bin/echo -e "LANG=\"en_US.UTF-8\"" >/etc/default/local EXPOSE 22 EXPOSE 80 CMD /usr/sbin/sshd -D 

Each instruction creates a new layer on the mirror, and each instruction must be prefixed in uppercase.

The first FROM, which specifies which mirror source to use

The RUN instruction tells docker to execute the command in the image and what is installed.

Then we use the Dockerfile file to build an image through the docker build command.

runoob@runoob:~$ docker build -t runoob/centos:6.7 . Sending build context to Docker daemon 17.92 kB Step 1 : FROM centos:6.7 ---> d95b5ca17cc3 Step 2 : MAINTAINER Fisher "fisher@sudops.com" ---> Using cache ---> 0c92299c6f03 Step 3 : RUN /bin/echo 'root:123456' |chpasswd ---> Using cache ---> 0397ce2fbd0a Step 4 : RUN useradd runoob ...... 

Parameter description:

-t Specify the name of the target image to create
. The directory where the Dockerfile file is located, and you can specify the absolute path of Dockerfile

Use docker images to check that the created image already exists in the list, and the image ID is 860c279d2fec.

runoob@runoob:~$ docker images REPOSITORY TAG IMAGE ID CREATED SIZE runoob/centos 6.7 860c279d2fec About a minute ago 190.6 MB runoob/ubuntu v2 70bf1840fd7c 17 hours ago 158.5 MB ubuntu 14.04 90d5884b1ee0 6 days ago 188 MB php 5.6 f40e9e0f10c8 10 days ago 444.8 MB nginx latest 6f8d099c3adc 12 days ago 182.7 MB mysql 5.6 f2e8d6c772c0 3 weeks ago 324.6 MB httpd latest 02ef73cf1bc0 3 weeks ago 194.4 MB ubuntu 15.10 4e3b13c8a266 5 weeks ago 136.3 MB hello-world latest 690ed74de00f 6 months ago 960 B centos 6.7 d95b5ca17cc3 6 months ago 190.6 MB training/webapp latest 6fae60ef3446 12 months ago 348.8 MB 

We can use the new image to create the container

runoob@runoob:~$ docker run -t -i runoob/centos:6.7 /bin/bash [root@41c28d18b5fb /]# id runoob uid=500(runoob) gid=500(runoob) groups=500(runoob) 

From the above, we can see that the new image already contains the user runoob we created.

Set image label ¶

We can use the docker tag command to add a new label to the image.

runoob@runoob:~$ docker tag 860c279d2fec runoob/centos:dev

Docker tag image ID, here is 860c279d2fec, user name, image source name (repository name), and new tag signature (tag).

Using the docker images command, you can see that ID is an extra label for the image of 860c279d2fec.

runoob@runoob:~$ docker images REPOSITORY TAG IMAGE ID CREATED SIZE runoob/centos 6.7 860c279d2fec 5 hours ago 190.6 MB runoob/centos dev 860c279d2fec 5 hours ago 190.6 MB runoob/ubuntu v2 70bf1840fd7c 22 hours ago 158.5 MB ubuntu 14.04 90d5884b1ee0 6 days ago 188 MB php 5.6 f40e9e0f10c8 10 days ago 444.8 MB nginx latest 6f8d099c3adc 13 days ago 182.7 MB mysql 5.6 f2e8d6c772c0 3 weeks ago 324.6 MB httpd latest 02ef73cf1bc0 3 weeks ago 194.4 MB ubuntu 15.10 4e3b13c8a266 5 weeks ago 136.3 MB hello-world latest 690ed74de00f 6 months ago 960 B centos 6.7 d95b5ca17cc3 6 months ago 190.6 MB training/webapp latest 6fae60ef3446 12 months ago 348.8 MB 