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thecodemaniac · 8 years ago

Text

LEARN DOCKER IN 15 MINUTES

I have written this blog to quickly introduce docker related details such as docker installation, creating images, etc.

How to install Docker?

Copy the following commands in a shell script and then run:

sudo apt-get install apt-transport-https ca-certificates \ curl software-properties-common curl -fsSL https://download.docker.com/linux/ubuntu/gpg | sudo apt-key add - sudo add-apt-repository "deb [arch=amd64] https://download.docker.com/linux/ubuntu \ $(lsb_release -cs) stable" sudo apt-get update sudo apt-get install docker-ce

How to validate the installation?

Run the command:

sudo docker version

The above command requires sudo because by default docker commands need root privileges to run on other add user to group name docker.

Output format

Client: Version: 17.03.0-ce API version: 1.26 Go version: go1.7.5 Git commit: 3a232c8 Built: Tue Feb 28 08:01:32 2017 OS/Arch: linux/amd64 Server: Version: 17.03.0-ce API version: 1.26 (minimum version 1.12) Go version: go1.7.5 Git commit: 3a232c8 Built: Tue Feb 28 08:01:32 2017 OS/Arch: linux/amd64 Experimental: false

What are the basic information commands?

How to create first image?

Here for the sake of simplicity we are going to use existing docker images which you can find from the below URL:

https://hub.docker.com/

Let us create the first docker image:

STEP 1 - Pull a light weight ubuntu image from the docker hub:

command :

sudo docker pull ubuntu

sudo is optional if you are a member of the docker group.

*If you want to pull an image with particular version suppose ubuntu xenial or trusty, mention it in the format:

image_name: release

command :

sudo pull ubuntu:xenial

Output

xenial: Pulling from library/ubuntu d54efb8db41d: Pull complete f8b845f45a87: Pull complete e8db7bf7c39f: Pull complete 9654c40e9079: Pull complete 6d9ef359eaaa: Pull complete Digest: sha256:dd7808d8792c9841d0b460122f1acf0a2dd1f56404f8d1e56298048885e45535 Status: Downloaded newer image for ubuntu:xenial

Verify it by executing:

sudo docker images

STEP 2 - To login to the image run the command:

sudo docker run -i -t ubuntu:xenial /bin/bash

-i = interactivity

-t = attached it to the terminal

package name = ubuntu:xenial

bin/bash = run the bash shell

Once you execute the above command, you will see that you are inside the docker container.

How to create multiple images simultaneously?

Docker can handle multiple containers with a single image.

Example:

Previously we have seen how to create a container by using the command:

sudo docker run -it ubuntu:xenial \bin\bash

If you run the above command, you will find the curser inside the container. Once you exit the container, check its status using the command

sudo docker ps

You will notice that there is container running. To run the container in the background use the -d option.

Now the command will be:

sudo docker run -itd ubuntu:xenial \bin\bash

Run the above commands multiple times. You will notice that each time there is a new hash code. This means multiple containers have been created in the background and you can verify them by:

sudo docker ps

Exercise

Do this exercise to understand more about running multiple containers from the single image.

1 - Download ubuntu image.

2 - Create a container which should be active in the background.

3 - Create a file called “hahahah.txt” in the container.

4 - Create another container by using the same image and this container should also be a daemon.

5 - Verify the difference between ‘container 1’ and '2’ as they are created from the same image.

How to customize images?

So far we have seen creating a container with an existing image. Now, let’s see how to customize or enhance the image.

In the previous example we have seen ubuntu image which is cool. The size of ubuntu image is hardly 140Mb.

The commands like ifconfig and other basic commands are not available, we have to install the package to make it available.

Let’s install python package in the container:

STEP 1 - Create a new container by using “ubuntu:xenial image”

sudo docker run -itd ubuntu:xenial /bin/bash

You are familiar with the above command.

STEP 2 - Install python package.

apt-get install python2.7

Once you have executed the above command it will install the package in your docker container.

STEP 3 - Come out of the container and now execute the:

sudo docker ps

You will see that the container is running and there will be a name assigned to it.

Example:

CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES 8072e7df6875 ubuntu:xenial "/bin/bash" 58 minutes ago Up 51 minutes sharp_heisenberg

Note: The variable name is used to distinguish multiple copies of the container created from the same name.

Let’s commit our changes here.

Syntax :

sudo docker commit -m "message" name_of_the_container your_new_image_name:version sudo docker commit -m "Added python package to ubuntu" sharp_heisenberg ubupython:version1

Verify by running sudo docker images

You will see your new image will be reflected create containers by using that image you will ubuntu with python installed package :)

If you have noticed that you will find a docker support for most of the repositories in github as its simplifies in the setup and easy to share.

Usually the docker supported images are not shipped with the repositories we have to build them locally with the help of dockerfiles.

A dockerfile is simplified way of declaring all the steps in one file and executing it will give a new required image

As our previous example we have seen creating an ubuntu image with python pre-installed, we have done that by getting inside the machine, we can avoid that and do it outside to.

Example:

1. Create a file let’s say ubuntu_python

2. Edit the file and add the following lines:

FROM ubuntu:latest

MAINTAINER samplename <[email protected]> RUN apt-get install python2.7

3. Lets build the docker image:

sudo docker build -t "ubuntupython:version2.7" ubuntu_python

It will create a docker image for you.

Note: If you’re installing package which needs to handle the user prompt the docker will fail to avoid that, so, use the below notations:

apt-get install -y packagename

***For any queries or doubts leave a comment or mail me at [email protected]

#docker #docker installation #docker image #docker single image #multiple images #docker ubuntu #technology

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thecodemaniac · 8 years ago

Text

LEARN DOCKER IN 15 MINUTES

I have written this blog to quickly introduce docker related details such as docker installation, creating images, etc.

How to install Docker?

Copy the following commands in a shell script and then run:

How to validate the installation?

Run the command:

sudo docker version

The above command requires sudo because by default docker commands need root privileges to run on other add user to group name docker.

Output format

What are the basic information commands?

How to create first image?

Here for the sake of simplicity we are going to use existing docker images which you can find from the below URL:

https://hub.docker.com/

Let us create the first docker image:

STEP 1 - Pull a light weight ubuntu image from the docker hub:

command :

sudo docker pull ubuntu

sudo is optional if you are a member of the docker group.

*If you want to pull an image with particular version suppose ubuntu xenial or trusty, mention it in the format:

image_name: release

command :

sudo pull ubuntu:xenial

Output

Verify it by executing:

sudo docker images

STEP 2 - To login to the image run the command:

sudo docker run -i -t ubuntu:xenial /bin/bash

-i = interactivity

-t = attached it to the terminal

package name = ubuntu:xenial

bin/bash = run the bash shell

Once you execute the above command, you will see that you are inside the docker container.

How to create multiple images simultaneously?

Docker can handle multiple containers with a single image.

Example:

Previously we have seen how to create a container by using the command:

sudo docker run -it ubuntu:xenial \bin\bash

If you run the above command, you will find the curser inside the container. Once you exit the container, check its status using the command

sudo docker ps

You will notice that there is container running. To run the container in the background use the -d option.

Now the command will be:

sudo docker run -itd ubuntu:xenial \bin\bash

Run the above commands multiple times. You will notice that each time there is a new hash code. This means multiple containers have been created in the background and you can verify them by:

sudo docker ps

Exercise

Do this exercise to understand more about running multiple containers from the single image.

1 - Download ubuntu image.

2 - Create a container which should be active in the background.

3 - Create a file called "hahahah.txt" in the container.

4 - Create another container by using the same image and this container should also be a daemon.

5 - Verify the difference between 'container 1' and '2' as they are created from the same image.

How to customize images?

So far we have seen creating a container with an existing image. Now, let's see how to customize or enhance the image.

In the previous example we have seen ubuntu image which is cool. The size of ubuntu image is hardly 140Mb.

The commands like ifconfig and other basic commands are not available, we have to install the package to make it available.

Let's install python package in the container:

STEP 1 - Create a new container by using "ubuntu:xenial image"

sudo docker run -itd ubuntu:xenial /bin/bash

You are familiar with the above command.

STEP 2 - Install python package.

apt-get install python2.7

Once you have executed the above command it will install the package in your docker container.

STEP 3 - Come out of the container and now execute the:

sudo docker ps

You will see that the container is running and there will be a name assigned to it.

Example:

CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES 8072e7df6875 ubuntu:xenial "/bin/bash" 58 minutes ago Up 51 minutes sharp_heisenberg

Note: The variable name is used to distinguish multiple copies of the container created from the same name.

Let's commit our changes here.

Syntax :

sudo docker commit -m "message" name_of_the_container your_new_image_name:version sudo docker commit -m "Added python package to ubuntu" sharp_heisenberg ubupython:version1

Verify by running sudo docker images

You will see your new image will be reflected create containers by using that image you will ubuntu with python installed package :)

If you have noticed that you will find a docker support for most of the repositories in github as its simplifies in the setup and easy to share.

Usually the docker supported images are not shipped with the repositories we have to build them locally with the help of dockerfiles.

A dockerfile is simplified way of declaring all the steps in one file and executing it will give a new required image

As our previous example we have seen creating an ubuntu image with python pre-installed, we have done that by getting inside the machine, we can avoid that and do it outside to.

Example:

1. Create a file let's say ubuntu_python

2. Edit the file and add the following lines:

FROM ubuntu:latest

MAINTAINER samplename <[email protected]> RUN apt-get install python2.7

3. Lets build the docker image:

sudo docker build -t "ubuntupython:version2.7" ubuntu_python

It will create a docker image for you.

Note: If you're installing package which needs to handle the user prompt the docker will fail to avoid that, so, use the below notations:

apt-get install -y packagename

***For any queries or doubts leave a comment or mail me at [email protected]

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