How to operate Docker and images

Find mirror

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

We can also use the docker search command to search for images. For example, we need a httpd mirror as our web service. We can use the docker search command to search for httpd to find a suitable image for us.

docker search httpd

Drag Image

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

docker pull httpd

Delete the image. Use the docker rmi command to delete the image. For example, we delete the hello-world image:

$ docker rmi hello-world

Create an image

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. Update the image from the created container and submit the image
2. Use Dockerfile instructions to create a new image

Update the image

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

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

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

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

At this time, the container with ID e218edb10161 is the container that has been changed according to our needs. We can commit the container copy through the command docker commit.

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

Description of each parameter:

• -m: Submit description information
• -a: Specify the image author
• e218edb10161: container ID
• runoob/ubuntu:v2: Specify the target image name to be created

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

runoob@runoob:~$ cat Dockerfile 
FROM centos:6.7
MAINTAINER Fisher "[email protected]"

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 image. The prefix of each instruction must be uppercase.

The first FROM specifies which mirror source to use

The RUN instruction tells Docker to execute commands within the image and what to install. . .

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 "[email protected]"
 ---> 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 be created

. : The directory where the Dockerfile is located. You can specify the absolute path of the Dockerfile.

Use docker images to check that the created image already exists in the list. 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 create a container using the new image

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 the image tag

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

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

docker tag The image ID, here 860c279d2fec , the user name, the image source name (repository name) and the new tag name (tag).

Using the docker images command, you can see that the image with ID 860c279d2fec has an additional tag.

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

This is the end of this article about Docker and image operation methods. For more relevant Docker and image operation content, please search for previous articles on 123WORDPRESS.COM or continue to browse the following related articles. I hope everyone will support 123WORDPRESS.COM in the future!