How to build Dockerfile

Step 1: Create Dockerfile
Step 2: Build Image using Dockerfile
[root@VM1 pseudo_cdh5]# docker build -t praveenprakasan/pseudo_cdh5 .

Step 3:Check Images
[root@VM1 pseudo_cdh5]# docker images
REPOSITORY                    TAG                 IMAGE ID            CREATED             VIRTUAL SIZE
praveenprakasan/pseudo_cdh5   latest              6b1a80eb3eaa        4 minutes ago       284.6 MB

Step 4: Run Images
[root@VM1 pseudo_cdh5]# docker run -d praveenprakasan/pseudo_cdh5
7d7eef2f0a9d799aef3b6d02701499b1c216802fa5c3a6248c8f937b32cab98d

Step 5 : Push Images into Docker Hub
[root@VM1 pseudo_cdh5]# docker push praveenprakasan/pseudo_cdh5
The push refers to a repository [praveenprakasan/pseudo_cdh5] (len: 1)
6b1a80eb3eaa: Image already exists
f97a61013132: Image successfully pushed
40d687642406: Image successfully pushed
4e5f1c990534: Image successfully pushed
14dab3d40372: Image successfully pushed
abe620e04d9d: Image already exists
8031fc57486d: Image already exists
a57086046415: Image already exists
245bcdbcd071: Image successfully pushed
47d44cb6f252: Image already exists
Digest: sha256:3ba3cb7f83d12e6bcc7dcc98234dc2d0131bbe75258bab31cef13c5ef9ae227e

Error: Cannot connect to the Docker daemon. Is 'docker -d' running on this host? or Docker dead but pid file exists

[root@pravi~]# sudo service docker status
docker dead but pid file exists

[root@pravi~]# sudo docker run hello-world
Cannot connect to the Docker daemon. Is 'docker -d' running on this host?


Solutions:

I faced the same problem when installing Docker 1.5 on CentOS 7 on Vagrant/VM. Upgrading DevMapper fixed the problem. To do so, run the command:

[root@pravi~]# sudo yum update device-mapper

Docker Installation On CentOS

Step 1: Update OS
[root@pravi~]# yum update -y 

Step 2:Install Docker
[root@pravi~]# curl -sSL https://get.docker.com/ | sh
+ sh -c 'sleep 3; yum -y -q install docker-engine'
warning: rpmts_HdrFromFdno: Header V4 RSA/SHA1 Signature, key ID 2c52609d: NOKEY
Importing GPG key 0x2C52609D:
 Userid: "Docker Release Tool (releasedocker) <docker@docker.com>"
 From  : https://yum.dockerproject.org/gpg

If you would like to use Docker as a non-root user, you should now consider
adding your user to the "docker" group with something like:

  sudo usermod -aG docker your-user

Remember that you will have to log out and back in for this to take effect!

Step 3: Start the Docker daemon.
[root@pravi~]# sudo service docker start
Starting cgconfig service:                                 [  OK  ]
Starting docker:                                                [  OK  ]

Step 4:
Verify docker is installed correctly by running a test image in a container.

[root@pravi~]# sudo docker run hello-world

Unable to find image 'hello-world:latest' locally

Pulling repository hello-world

975b84d108f1: Download complete

3f12c794407e: Download complete

Status: Downloaded newer image for hello-world:latest

Hello from Docker.

This message shows that your installation appears to be working correctly.

To generate this message, Docker took the following steps:

 1. The Docker client contacted the Docker daemon.

 2. The Docker daemon pulled the "hello-world" image from the Docker Hub.

 3. The Docker daemon created a new container from that image which runs the

    executable that produces the output you are currently reading.

 4. The Docker daemon streamed that output to the Docker client, which sent it

    to your terminal.

To try something more ambitious, you can run an Ubuntu container with:

 $ docker run -it ubuntu bash

Share images, automate workflows, and more with a free Docker Hub account:

 https://hub.docker.com

For more examples and ideas, visit:

 https://docs.docker.com/userguide/

Step 5: Show Images 

[root@pravi~]# docker images

REPOSITORY          TAG                 IMAGE ID            CREATED             VIRTUAL SIZE

hello-world         latest              975b84d108f1        9 weeks ago         960 B

Step 6: Run Images 

[root@pravi~]# docker run -it ubuntu bash