Chris Hines

Webinar Q&A: Docker Overview

harish_jayakumarThanks everyone who joined us during our Docker Overview webinar. During this webinar, we gave a high level introduction to Docker, and let the audience see the platform in action during a live demo. The recording of the webinar is available to watch here or below.

Featured presenter, Harish Jayakumar, Solutions Engineer at Docker, Inc., shares his answers to questions he received during the live presentation:


What are some of the most common use cases for Docker?

The most common use case is solving for the inconsistencies between development, test and production. Continuous integration/Continuous deployment is an issue that almost all Developers and DevOps teams are struggling with and Docker solves that for you as we saw in the demo now. Many organizations are also changing their design from monolithic applications to a microservices architecture and Docker also helps with that transition.

How do you maintain the same url when new containers are deployed?

Actually it just happened to be the same URL in this case :). It could be any of the 2 instances in the swarm cluster. You would do a docker  ps ( docker-swarm ps  in my case) get the URL of the instance and launch your application there. In this case the URL is my Amazon EC2 instance with the port 5000.

Is Docker Trusted Registry(DTR) running inside a container?

DTR is deployed as a multi-service/multi-container application. It is composed of 6 different containers. So yes.

Can you demo how to enable communications between two separate containers

What you would do is use the “– link” option to link the two containers to one another. You can also use Docker Compose as well. There is also work being being done in libnetwork that will make the communication easier and seamless.

Based on your talks with customers, what are the most common questions?

Depends where they are in the Docker learning curve. Some folks are just trying to get started and ask things like what’s the difference between containers and VMs.

Basically think of VM as hardware virtualization and Containers as OS virtualization. For containers , you don’t need a full blown OS. You only add what the application needs is wrapped into the container ( this of it as “just enough OS”) . In terms of VM, every VM has their own full blown OS and application within it. That’s the big difference.

Others ask questions like how do I go and manage all my containers at scale, and still have visibility. Docker has something called Project Orca which we talked about at DockerCon a couple of months back. It is an orchestration platform to manage your containers.

What is the most basic use case for using containers?

Continuous Integration/Continuous deployment between development, test and production. If you haven’t; started yet, you can download or have your developers download docker and get started. Developers can start wrapping their code with all the dependencies and push them as an image. You can then have your test team pull those images and use it and the same scenario with your production team.

Could you explain a little bit more about how Docker helps customers lower their TCO?

With Docker you can reduce your development lifecycle, get more releases out, reuse images, iterate faster and deploy your applications really quick. As a result you see immediate benefits and savings. As you saw in the presentation ING, GILT Group and BBC News have already seen huge benefits in being able to innovate faster and get more releases out, move from monolithic applications to a microservices model and reduce their failure rates in production.

Docker containers also provide you with the flexibility to spin containers up and down quickly depending on your demand. This allows you to make efficient use of your existing compute resources thus achieving better server density.

Will docker containers run natively on a OS X host?

No. Docker containers requires a linux host and runs natively on them. With the next release of Windows Server – Windows server 2016 Docker containers will also run on windows. For Mac you need can use a linux virtual machine on something like Virtualbox, and run your Docker containers there. What you saw in the demo was me running docker on a linux host on amazon EC2 instance(s).

What do we have to consider from a networking and security standpoint when developer teams are considering to use docker? Are there any basic requirements to separate different containers from different tenants?

Docker containers provide an additional layer of isolation, making your infrastructure safer by default. Under the hood Docker makes use of namespaces, capabilities and cgroups to provide security. A good place to start will be that has a few videos and whitepapers covering Docker security and address any concerns around Docker security.

From a networking standpoint with Docker you can do most of the things you are doing on your infrastructure today – creating a separate VLAN, enabling multi host container communications and having containers on the same host talk to each other.You can also create multiple networks and isolate each of them and set it such that containers in one network do not talk to the other one. I would also recommend taking a look at libnetwork, which will be part of our next Docker engine release (version 1.9).

We hope this answers a lot of your questions related in getting started with Docker images, volumes and storage. There are additional sessions that will discuss planning considerations and best practices – make sure to check them out.


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Chris Hines

Webinar Q&A: Docker Overview

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