I lose my data when the container exits

Question

Despite Docker's Interactive tutorial and faq I lose my data when the container exits.

I have installed Docker as described here: http://docs.docker.io/en/latest/installation/ubuntulinux without any problem on ubuntu 13.04.

But it loses all data when exits.

iman@test:~$ sudo docker version
Client version: 0.6.4 
Go version (client): go1.1.2 
Git commit (client): 2f74b1c 
Server version: 0.6.4 
Git commit (server): 2f74b1c 
Go version (server): go1.1.2 
Last stable version: 0.6.4 


iman@test:~$ sudo docker run ubuntu ping
2013/10/25 08:05:47 Unable to locate ping 
iman@test:~$ sudo docker run ubuntu apt-get install ping
Reading package lists... 
Building dependency tree... 
The following NEW packages will be installed: 
  iputils-ping 
0 upgraded, 1 newly installed, 0 to remove and 0 not upgraded. 
Need to get 56.1 kB of archives. 
After this operation, 143 kB of additional disk space will be used. 
Get:1 http://archive.ubuntu.com/ubuntu/ precise/main iputils-ping amd64 3:20101006-1ubuntu1 [56.1 kB] 
debconf: delaying package configuration, since apt-utils is not installed 
Fetched 56.1 kB in 0s (195 kB/s) 
Selecting previously unselected package iputils-ping. 
(Reading database ... 7545 files and directories currently installed.) 
Unpacking iputils-ping (from .../iputils-ping_3%3a20101006-1ubuntu1_amd64.deb) ... 
Setting up iputils-ping (3:20101006-1ubuntu1) ... 
iman@test:~$ sudo docker run ubuntu ping
2013/10/25 08:06:11 Unable to locate ping 
iman@test:~$ sudo docker run ubuntu touch /home/test
iman@test:~$ sudo docker run ubuntu ls /home/test
ls: cannot access /home/test: No such file or directory 

I also tested it with interactive sessions with the same result. Did I forget something?

EDIT: IMPORTANT FOR NEW DOCKER USERS

As @mohammed-noureldin and others said, actually this is NOT a container exiting. Every time it just creates a new container.

Answer 1

I have got a much simpler answer to your question, run the following two commands

sudo docker run ubuntu
sudo docker ps -a

the above ps -a command returns a list of all containers. Take the name of the container which references the image name - 'ubuntu' . docker auto generates names for the containers for example - 'ubuntu-containername'

sudo docker start ubuntu-containername

sudo docker exec -ti ubuntu-containername bash

This above command will start the stopped container and the next command helps you login to the container with bash shell. From this point on any changes you make in the container is automatically saved by docker. For example - apt-get install curl inside the container You can exit the container without any issues, docker auto saves the changes.

On the next usage, All you have to do is, run these two commands every time you want to work with this container.

sudo docker start ubuntu-containername
sudo docker exec -ti ubuntu-containername bash

Answer 2

You need to commit the changes you make to the container and then run it. Try this:

sudo docker pull ubuntu

sudo docker run ubuntu apt-get install -y ping

Then get the container id using this command:

sudo docker ps -l

Commit changes to the container:

sudo docker commit <container_id> iman/ping 

Then run the container:

sudo docker run iman/ping ping www.google.com

This should work.

Answer 3

In addition to Unferth's answer, it is recommended to create a Dockerfile.

In an empty directory, create a file called "Dockerfile" with the following contents.

FROM ubuntu
RUN apt-get install ping
ENTRYPOINT ["ping"]

Create an image using the Dockerfile. Let's use a tag so we don't need to remember the hexadecimal image number.

$ docker build -t iman/ping .

And then run the image in a container.

$ docker run iman/ping stackoverflow.com