What should I do if I cannot access docker after it is started?

Solution to the inaccessibility of docker after starting: 1. Execute the "docker run -itd -p" command; 2. Enter "docker ps -a" to view "ports"; 3. Check the linux version and docker version ; 4. Enter the "yum update" command line to upgrade the kernel; 5. Restart the kernel.

The operating environment of this tutorial: Windows 7 system, Docker version 20.10.11, Dell G3 computer.

What should I do if I cannot access docker after it is started?

The Docker container is started successfully but the browser cannot be accessed (after the Docker container is started, check docker ps -a and you cannot see the ports (the ports column is empty) | The linux kernel version and the docker version are incompatible)

Scenario: The Docker container is started successfully but the browser cannot access it

I am learning the basic operations of the Docker container. I pulled the tomcat image and entered the run container command to run the container. There was no problem with a series of operations, but when browsing When the server accesses the port, it cannot access it

[root@localhost ~]# docker run -d -p 8081:8080 --name mytomcat b8dfe9ade316

1. After the Docker container is started, check docker ps -a and you cannot see the ports (the ports column is empty)

After testing various command lines, I finally entered the command to display all container information and found that the ports line was empty! ! !

[root@localhost ~]#  docker ps -a

Then I didn’t know what keywords to find to describe this situation, so I tried various methods, such as uninstalling and reinstalling the old version of tomcat, turning off the firewall, and setting up the firewall to allow or restrict specified IPs. Neither the port nor the firewall worked. I even formatted the output to display the specified column but still couldn't see the ports. After many twists and turns, I finally found the method of blogger Jacen_Chou and tried it, and it worked! ! ! Thank you blogger Jacen_Chou for your help. My mood is just like what the blogger said at the end. When I saw the success, I was so excited that I almost cried.

The blogger said that as long as -d Just add it in front, and I finally found out that this situation is called Docker port mapping not working

[root@localhost ~]# docker run -itd -p 8081:8080 --name mytomcat b8dfe9ade316

Then enter docker ps -a, and finally see the contents of the ports line

2. The linux kernel version and the docker version are incompatible

I thought the problem had been solved. Logically speaking, there was no problem. I opened the browser happily, but still No 5555, I continued to look for the reason, and returned to the original keywords. The docker container was started successfully but could not be accessed. After a search, I saw that Qingren blogger said that the Linux system kernel may be low, and the docker version is the latest version. So it's not compatible.

I quickly checked my linux version and docker version, and the result is really like this. My docker is version 20.10.11, and linux is only 3.8. It took me a long time to figure it out. It turns out that the problem is version incompatibility. , quickly enter the yum update command line to upgrade the kernel

#查看linux内核版本
[root@localhost ~]# uname -sr
#查看docker版本
[root@localhost ~]# docker version
#升级linux内核版本，升级所有包同时也升级软件和系统内核
[root@localhost ~]# yum update -y

After a long wait for the upgrade, I suggest you search for how to upgrade the larger version of the Linux kernel version, because yum update is only suitable for small version upgrades, and there are many steps to upgrade the large version. I'm too lazy to try.

Finally, don’t forget to restart centos and the container after the upgrade.

Finally, I finally saw my damn Tom Cat~~

Solution:

Check whether the Docker port mapping is successful, and whether the Linux kernel version and the docker version are compatible. If they are not compatible, there are two methods, either reduce the docker version (uninstall the higher version and reinstall it) Either upgrade the Linux kernel version, and don’t forget to restart the host after the upgrade.

Ended with flowers~~~

Recommended learning: "docker video tutorial"

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