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The purpose of this article is to share with you what problems you will encounter when using version 0.9.1 of Docker in Docker. The editor thinks it is very practical, so share it with you as a reference and follow the editor to have a look.

When I tested, the problem with using version 0.9.1 of Docker:

The image created by 1.Dockerfile cannot add tag and name to the new mirror even if-t is added.

two。 The / etc/hosts that uses the-- link parameter but cannot find the information about the parent container in the child container makes it impossible to ping the hostname directly.

The key to solving the problem:

Install the latest version of docker (it seems that there are many previous versions of bug)

Installation steps (ubuntu) (refer to the self-official website manual):

1. Install assistive tools for parsing https:

Apt-get install apt-transport-https

I strongly recommend that you restart the machine after installation, otherwise apt may not be able to resolve the https URL!

two。 Add key and source:

Apt-key adv-keyserver hkp://keyserver.ubuntu.com:80-recv-keys 36A1D7869245C8950F966E92D8576A8BA88D21E9sh-c "echo deb https://get.docker.io/ubuntu docker main\ > / etc/apt/sources.list.d/docker.list" sudo apt-get update

3. Install lxc-docker:

Apt-get install lxc-docker

4. Check the docker version:

Docker version

The version number is shown as follows (1.2.0):

Root@docker:~# docker versionClient version: 1.2.0Client API version: 1.14Go version (client): go1.3.1Git commit (client): fa7b24fOS/Arch (client): linux/amd64Server version: 1.2.0Server API version: 1.14Go version (server): go1.3.1Git commit (server): fa7b24f

Test Dockerfile:

I pull a minimized ubuntu image:

Docker pull dbehnke/ubuntu1404

Create a file called Dockerfile in the local directory,

Vi Dockerfile# add the following # my test imageFROM dbehnke/ubuntu1404:latest # create a new imageMAINTAINER Hochikong # maintainer information from the existing image RUN mkdir-p / home/backupRUN mv / etc/apt/sources.list / home/backupRUN wget http://172.16.77.157/sources.list-P / etc/apt # download the localized sources.list file from the apache2 server of the host (172.16.77.157) Because foreign sources are too slow RUN apt-get update

Perform build:

Docker build-t = "hochikong/local:v1". # Don't forget the latter point, which refers to the local Dockerfile file; in addition, hochikong must be lowercase. I typed the uppercase prompt "only [a-z0-9] are allowed, size between 4 and 30" before.

See if my image has been created:

The problem of the previous article has finally been solved.

Test-use of the link parameter:

Start a container named base (parent container) first:

Docker run-d-p 1000R 5000-- name base training/webapp python app.py

View status:

Root@docker:~# docker psCONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES928ebabc26eb training/webapp:latest "python app.py" 32 seconds ago Up 31 seconds 0.0.0.0 seconds 1000-> 5000/tcp base

You can see that the container has been started, and port 1000 of the host is bound to port 5000 of the container, which is named base.

Then start a child container named web:

Docker run-d-p 2000 5000-- name web-- link base:base training/webapp python app.py

Check the status again:

Root@docker:~# docker psCONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES21f82b33c27a training/webapp:latest "python app.py" 30 seconds ago Up 29 seconds 0.0.0.0 seconds 2000-> 5000/tcp web 928ebabc26eb training/webapp:latest "python app.py "2 minutes ago Up 2 minutes 0.0.0.0purl 1000-> 5000/tcp base Web/base

As you can see, the web container has been started. At the same time, web/base is added to the NAMES column of the base container. In fact, in "web/base", web refers to the child container connected to the base, but the "/" is followed by the alias of the link (recommended is the same as the container name of the parent container, and then you will know why)

I start another child container called web2, which is also connected to the base:

Docker run-d-p 3000 5000-- name web2-- link base:connection2 training/webapp python app.py

Look at the results of docker ps:

Root@docker:~# docker psCONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMESd180046639f4 training/webapp:latest "python app.py" 57 seconds ago Up 56 seconds 0.0.0.0 seconds ago Up 3000-> 5000/tcp web2 21f82b33c27a training/webapp:latest "python app.py" 5 minutes ago Up 5 minutes 0.0.0.0minutes 2000-> 5000/tcp web 928ebabc26eb training/webapp:latest "python app.py" 8 minutes ago Up 8 minutes 0.0.0.0minutes 1000-> 5000/tcp base Web/base,web2/connection2

There is an extra "web2/connection2" in the NAMES column of base (you can refer to https://docs.docker.com/userguide/dockerlinks/ to see the meaning of "--link name:alias")

Let's connect to web2 through nsenter and get the PID number first:

Root@docker:~# docker inspect web2 | grep Pid # docker inspect CONTAINERNAME can output the details of the specified container in JSON format. I directly use grep to filter out "Pid": 21275

Connect to the web2:

Nsenter-target 21275-mount-uts-net-ipc-pid # use that pid value

View the container's / etc/hosts file:

Let me check the IP address of base again:

Root@docker:~# docker inspect base | grep IP "IPAddress": "172.17.0.11", "IPPrefixLen": 16

Do you think it's lame! In fact, 172.17.0.11 is the IP address of base, but in web2, it shows the name of the link, and your ping host connection2 is actually the ping container base. But I think it's unreasonable! Why does the hosts file write the name of the link instead of the container name of the parent container?

Base container under ping:

Ping is ping.

It is because it is unreasonable that I strongly recommend that you write:

Docker run-d-p 2000 5000-- name web-- link base:base training/webapp python app.py

Make the name of the link (base after ":") the same as the parent container name (base before ":")!

If you connect to the web container, you can see the information in hosts. In this way, the name of the ping parent container is more reasonable:

Note:

The information for child containers is not included in the base container:

Pay particular attention to this when designing an application (it is impossible to make the web service the parent container and the database the child container, right? )

Thank you for reading! This is the end of the article on "what problems you will encounter when using 0.9.1 version of Docker in Docker". I hope the above content can be of some help to you, so that you can learn more knowledge. if you think the article is good, you can share it for more people to see!

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