Docker Cookbook

54 | Chapter 2: Image Creation and Sharing

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2.9 Publishing Your Image to Docker Hub
Problem
You write a Dockerfile and build an image for a useful container. You want to share
this image with everyone.
Solution
Share this image on the 
Docker Hub
. Docker Hub is to Docker what 
GitHub
is to
source code. It allows anyone to host its image online and share it publicly or keep it
private. To share an image on Docker Hub, you need to do the following:
• Create an account on Docker Hub.
• Log in to the hub on your Docker host.
• Push your image.
Let’s get started. Registering requires only a valid email address. Head over to the
signup page
 and create an account. After verifying the email address that you used to
create the account, your registration will be complete. This free account will allow
you to publish public images as well as have one private repository. If you want to
have more than one private repository, you will need to pay a subscription.
Now that you have an account created, you can head back to your Docker host, select
one of your images, and use the Docker CLI to publish this image on your public
repository. This will be a three-step process:
1. Log in with 
docker login
. This will ask for your Docker Hub credentials.
2. Tag an existing image with your username from Docker Hub.
3. Push the newly tagged image.
The login step will store your Docker Hub credentials in a 
~/.dockercfg
file:
$ docker login
Username: how2dock
Password:
Email: [e-mail]
Login Succeeded
$ cat ~/.dockercfg
{"https://index.docker.io/v1/":{"auth":"..........",
"email":"[e-mail]"}}
If you check the list of images that you currently have, you see that your Flask image
from 
Recipe 2.4
 is using a local repository and has a tag called 
latest
: