About docker registry

• You can build your own images(with multiple containers) by using docker
• To build your images you use various apps, libraries etc

• Then two problems comes

  1. Where does the apps and libraries comes from
  2. How/where we store these images

• To solve this problem docker introduces docker-registry

• Docker registry allows you to upload, download and share your own images

• If simply says, the Docker registry is Docker’s in-build way to share images

• It is an open-source project and can be found at https://github.com/dotcloud/docker-registry

How docker registry works

• You can take/pull libraries, apps from registry to build your images,
• After building images you can upload/push your images to the registry
• These pushed images can be downloaded in another environment
• Consider following scenario

Traditional deployments

• Traditional way of production deployment is, you need to manually deploy all your stuffs(source codes, environment upgrades etc..) to production environment (by using shell scripts or other kind of mechanism).
• Docker makes the life more easy...

Docker way of deployment

• You can build a docker image from your development machine push it to docker registry
• From production machine you can pull it.. thats it
• Another advantage with docker and docker registry is you don't need manually upgrade your production environment(for an instance upgrade java in production)
• You can just create new image with upgraded java, replace the existing image in production with newly created image

Private docker registry

• Docker registry is open source project - docker-registry
• You can take the docker registry code and host in your own local server, in order to use as a private docker registry
• After setting up private registry you can push, pull images to and from it

How to use private registry on OS-X

• Docker use linux kernal features
• In order to use docker in OS-X we have to install linux virtual machine and run the docker server on it
• We use boot2docker light weight linux virtual machine
• OS-X host contains docker client

• In order to add private docker registry, we ssh to boot2docker VM add registry entry into it
• Following are the steps

1. ssh to boot2docker VM

## first need to up the boot2docker VM
boot2docker up

## ssh to boot2docker VM
boot2docker ssh

2. Add registry entry

• If your private registry doesn't supports SSL(HTTPS), add following entry(insecure-registry) to /var/lib/boot2docker/profile

echo 'EXTRA_ARGS="--insecure-registry <YOUR INSECURE HOST>"' | sudo tee -a /var/lib/boot2docker/profile

• Now your boot2docker profile file looks like below
• Please note that private registry host is in our local environment(IP - 10.2.4.201)

3. Restart docker server(service) from boot2docker

sudo /etc/init.d/docker restart

4. Search and Pull from private registry

• Now you can search, pull, push the images in your private registry from you host OS-X machine
• It can be done via the docker client installed in your OS-X machine

## search postgres from the private registry
docker search 10.2.4.201/postgres

## install postgres from the private registry
docker run -p 5432:5432 --name postgres -d 10.2.4.201/postgres:latest

Reference

• https://sysadmincasts.com/episodes/31-introduction-to-docker
• https://keyholesoftware.com/2014/11/20/docker-vms-code-migration-and-soa-solved/
• http://blog.thisisfeifan.com/2014/11/private-docker-registry-push-issue.html
• http://viget.com/extend/how-to-use-docker-on-os-x-the-missing-guide
• http://blog.thisisfeifan.com/2014/11/private-docker-registry-push-issue.html