Build your own docker image

Method1 is quite old and not cleaned one . Its like a snapshot .

Method2 is clean one, we build from the scratch, and we maintain the docker file. This is one we are going to look in detail.

Method1:

1. Launch the existing docker image (preferably official image such as ubuntu)
2. Login to the docker and do your changes (such as installing the app, creating the files etc)
3. Commit your changes in to new image

Let us see this method in detail.

Example.

Create the docker image with ssh server in Ubuntu.

Run the contrainer with ubuntu imagedocker run -i -t ubuntu bash

cloud@mkube:~$ sudo docker run -i -t ubuntu bash
root@3d507f55945f:/#

Install openssh server

root@3d507f55945f:/# apt-get update
......
root@3d507f55945f:/# apt-get install openssh-server

Configure & start the openssh server

root@3d507f55945f:/# mkdir /var/run/sshd
root@3d507f55945f:/# echo 'root:demo' | chpasswd
root@3d507f55945f:/# sed -i -e 's:UsePAM no:UsePAM yes:g' /etc/ssh/sshd_config
root@3d507f55945f:/# sed -i -e 's:PermitRootLogin without-password:PermitRootLogin yes:g' /etc/ssh/sshd_config
root@3d507f55945f:/# service ssh start   
 * Starting OpenBSD Secure Shell server sshd                                                                            [ OK ] 
root@3d507f55945f:/#

Note: username root, password demo

To Test the ssh login to the docker container:

To know the ip address of the container:

cloud@mkube:~$ sudo docker inspect 3d507f55945f
........
"IPAddress": "172.17.0.2",
.......

Now ssh to the IP:

cloud@mkube:~$ ssh [email protected]
[email protected]'s password:

To see the changes in the docker image happend(file changes with respect to base image) :

loud@mkube:~$ sudo docker ps -a
CONTAINER ID        IMAGE               COMMAND                  CREATED             STATUS                      PORTS               NAMES
3d507f55945f        ubuntu              "bash"                   22 minutes ago      Up 22 minutes                                   dreamy_payne
cloud@mkube:~$ sudo docker diff 3d507f55945f
C /etc/alternatives
A /etc/alternatives/rcp
A /etc/alternatives/rcp.1.
.....
cloud@mkube:~$

To persist/save the changes:

docker commit <dockerid> <imagename>

cloud@mkube:~$ sudo docker commit  3d507f55945f suresh/sshserver
sha256:a0c78c0d6f1d980192d086513f8b54618c75f4df196a2ebe1e62c52392a324c4
cloud@mkube:~$

To see the new docker image created:

cloud@mkube:~$ sudo docker images
REPOSITORY          TAG                 IMAGE ID            CREATED             SIZE
suresh/sshserver    latest              a0c78c0d6f1d        53 seconds ago      215MB
ubuntu              latest              2d696327ab2e        3 weeks ago         122MB
jenkins             latest              7b8e864de864        3 weeks ago         812MB
hello-world         latest              05a3bd381fc2        4 weeks ago         1.84kB
cloud@mkube:~$

Method2:

Write the docker configuration file and launch it directly.

Reference : https://docs.docker.com/engine/reference/builder/

Procedure:

1. Create a docker file
2. Build the docker image from the docker file
3. Push your image in to docker repo(optional)

Simple Example:

Lets run my python application (https://github.com/sureshkvl/python-projects/blob/master/sms/sms.py in ubuntu trusty image. it exposes the 5000 Port and runs REST Server.

Download the sms.py & requirements.txt from github and keep it in the working dir.

Create docker file(Dockerfile):

FROM ubuntu:trusty
WORKDIR /app
COPY sms.py /app/
COPY requirements.txt /app/
RUN apt-get update && apt-get install -y python python-pip
RUN pip install -r requirements.txt
EXPOSE 5000
CMD ["python", "sms.py"]

Just List the file in the dir:

cloud@mkube:~/sms$ ls
Dockerfile  requirements.txt  sms.py
cloud@mkube:~/sms$

Build the docker image

cloud@mkube:~/sms$sudo docker build -t suresh/sms:v2 -f Dockerfile  .

This will build the image and save as suresh/sms repository and tag v2.

To run a container from this image:

cloud@mkube:~/sms$ sudo docker run -d -p 5000:5000 suresh/sms:v2
24f82cea4706845f817e57b5062685994b1d9559b3d002b99d182cac9e5b031e
cloud@mkube:~/sms$ curl localhost:5000/students
{}
cloud@mkube:~/sms$

Cool. it works.

Method2-A:

This is same as Method2, but it automates the build process using Make tools as a Code. So the docker image build process will be maintained in version control system.

Refer this repo.

https://github.com/sureshkvl/kubernetes-examples/tree/master/docker-build

How to Push the Images to DockerHUB:

Login to dockerhub

sudo docker login

cloud@mkube:~/$ sudo docker login
Login with your Docker ID to push and pull images from Docker Hub. If you don't have a Docker ID, head over to https://hub.docker.com to create one.
Username: sureshkvl
Password: 
Login Succeeded

sudo docker push <image>

cloud@mkube:~/docker-build$ sudo docker push sureshkvl/test
The push refers to a repository [docker.io/sureshkvl/test]
e8090bbd248d: Pushed 
d11f970b132f: Pushed 
854aaa736782: Pushed 
4ade52c3fc78: Pushed 
5bd3619c9a53: Pushed 
7fb9ba64f896: Pushed 
4e1e6ac5b9d6: Pushed 
48daf661d621: Pushed 
bf59e7acf5c4: Pushed 
c47d9b229ca4: Pushed 
1-1: digest: sha256:ee72455313c0955551661b5a6718131a0f865c4eb46f371c7035efcfc68bb694 size: 2403
e8090bbd248d: Layer already exists 
d11f970b132f: Layer already exists 
854aaa736782: Layer already exists 
4ade52c3fc78: Layer already exists 
5bd3619c9a53: Layer already exists 
7fb9ba64f896: Layer already exists 
4e1e6ac5b9d6: Layer already exists 
48daf661d621: Layer already exists 
bf59e7acf5c4: Layer already exists 
c47d9b229ca4: Layer already exists 
1-2: digest: sha256:ee72455313c0955551661b5a6718131a0f865c4eb46f371c7035efcfc68bb694 size: 2403
cloud@mkube:~/docker-build$