What is a Docker Image? (And how do you use one with IronWorker?)

What is a Docker image?

Love them or hate them, containers have become part of the infrastructure running just about everything. From Kubernetes to Docker, almost everyone has their version of containers. The most commonly used is still Docker. IronWorker was among the very first to combine serverless management with containers. In this article we will give a high-level overview of what a Docker image is, and how IronWorker uses them.

So, What is a Docker image?

To start, we need to have an understanding of the Docker nomenclature and environment. There is still not a clear consensus on terms in regards to containers. What Docker calls one thing, Google calls another, and so on. We will only focus on Docker here. (for more on Docker vs Kubernetes, read here).

Docker has three main components that we should know about in relation to IronWorker:

  1. Docker file
  2. Docker image
  3. Docker container

1) Docker File

A Docker file is the set of instructions to create a Docker image.

Let’s keep it simple. Docker files are configuration files that “tell” Docker images what to install, update, etc. Basically the Docker file says what to build that will be the Docker image.

2) Docker Image

A Docker image is the set of processes outlined in the Docker file. It is helpful to think of these as templates created by the Docker files. These are arranged in layers automatically. Each layer is dependent on the layer below it. Each layer then becomes more abstracted than the layer below.

By abstracting the actual “instructions” (remember the Docker files?), an environment that can function with its resources isolated is created. While virtual machines relied on calling OS level resources, containers have eliminated this. In turn, this creates a lightweight and highly scalable system. IronWorker takes these images and begins the process of creating and orchestrating complete containers. What exactly is the difference between a Docker image and a Docker container? Let’s see.

3) Docker Containers

Finally we come to the containers. To simplify, we can say that when a Docker image is instantiated it becomes a container. By creating an instance that draws on system resources like memory, the container begins to carry out whatever processes are together within the container. While separate image layers may have different purposes, Docker containers are formed to carry out single, specific tasks. We can think of a bee vs. a beehive. Individual workers carry out asynchronous tasks to achieve a single goal. In short, containers are packages which hold all of the required dependencies to run an application.

After the container has been run, The Docker image is inert and inactive. This is because Docker image has carried out its purpose and now serves only as a meta reference.

IronWorker and Docker

So, you have your containers configured and everything is ready to go. What next? While Docker containers can function on their own, things like scaling workloads is much faster, more reliable, and easier with an orchestrator. IronWorker is one such container orchestrator, with some unique properties. 

An orchestrator adds another layer of abstraction to implementing and running containers. This has become known as “serverless” in recent years. While there is no such thing as a truly serverless, the term simply means there is no server management involved. By this point in the configuration, we have likely all but forgot about our original Docker image.

Forgetting about managing a server to react to spikes in traffic or other processing needs greatly simplifies a developer’s job. Tasks and other processes are scaled automatically. At the same time this allows for detailed analytics. Because the containers are managed by IronWorker, whether they are short lived or take days, the jobs are completed with minimal developer input after the initial setup.

What about migrating to other clouds or on-premise?

Traditionally, containers have been cloud based. As new options develop beyond just Amazon Web Services, the need to deploy flexible tools increases. Obviously devops changes frequently. Sometimes it even changes daily. One of the key benefits to IronWorker is that exporting your settings (as Docker images) and continuing on, either redundantly or in new iterations, in varying environments is the easiest in the marketplace. This includes deploying fully on-premise. This ability to maintain freedom from vendor lock-in and future needs is what separates IronWorker from the rest.

Start IronWorker now with a free 14 day trial here.

Docker, Inc isn’t Dead

Chris Short recently wrote up a piece entitled Docker, Inc is Dead, with a prediction that the company would no longer exist sometime in 2018.  It’s well written and he does a good job of running through some of Docker’s history in recent years.  Although I agree with some of his sentiments, I don’t think Docker, Inc will exit the stage anytime soon.  Here are some reasons I think Docker, Inc will live a healthy life in 2018.

Docker is Good Software

This was the first point in Chris’ piece, and he’s right.  Docker definitely helped widen the spotlight on *n?x kernels.  Discussions around namespaces, cgroups, lxc, zones, jails, etc… lit up across communities in different disciplines.  Dockers’ simple interface lowered the barrier of entry for non-administrators, and the developer community immediately added it to their workflows.  Docker released EE/UCP, and larger organizations jumped on board.  It “is” good software for developers, SMB’s, and large organizations, and Docker, Inc isn’t slowing down development efforts.

DOCKER HAS FRIENDS

“I’m really excited to welcome Solomon and Docker to the Kubernetes community”.  Brendan Burns (of Microsoft, Lead Engineer of Kubernetes) definitely made me do a double take when he said that on stage at DockerCon EU a few months ago.  Many people I spoke to at the conference referenced that statement and saw this as a big blow to Docker.  “Who’s joining who’s community? ”  The thing is, the real purpose of Brendan’s talk was about the collaboration between companies, and the effort to make our lives as developers and administrators better.  The whole “it takes a village to raise a child” saying.  This village is composed of some of the brightest engineers from many of the world’s largest companies, and they’re all striving to make things better.  Docker and Kubernetes worked together, and the Kubernetes integration into UCP made perfect sense.

Docker has business

They don’t have a lack of coherent leadership.  They’ve received a ton of money, their marketing is great, and they’re acting like what they are;  a rapidly growing company moving into the enterprise market.  Were some of their keynotes awkward at DockerCon EU this year?  Yes.  Were there fantastic sessions from customers who shared real-life Docker success stories?  Yes.  Have they made some mistakes here and there?  Yes.  Have they moved past those and grown?  Yes.  If you’ve been around the block and watched small companies rapidly grow into behemoths, this is all typical.  Growing isn’t easy.  Their “Modernizing Enterprise Applications” mantra is perfect.  There are countless technical budgets from Fortune 10,000 companies that Docker, Inc will capitalize on.  The best part is that they’ll actually be making a positive difference.  They are not snake-oil salesmen.  These companies will probably see real ROI in their engagements.

Conclusion

Docker, Inc isn’t going to be acquired (yet) or close their doors.  There is a lot going on at Docker, Inc right now but they aren’t signs of a company that is getting ready for a sale.

It’s a company that’s based on OSS with a lot of opportunity in the market.  While one of the products at Iron is Docker-based, we use a wide variety of software from many companies with roots in OSS.  We’re happy to pay for a higher level of support and features for OSS software backed by a business.  For other projects, we often donate through Open Collective to help maintainers and small development teams.  Docker’s donation of containerd was a great move and I think it is a project that fits perfectly into CNCF’s charter.

While Docker, Inc is moving upstream, they haven’t at all abandoned its real users;  developers.   We use Docker daily, contribute back when we can, and are optimistic about its trajectory as a business and a product.  Docker, Inc has a lot of room to grow, and in 2018, it will.

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Shepherding Containers

Shepherding Containers

Thanks to Yahoo for the base image CC BY 2.0

As one of the earliest users of Docker, I’ve had the pleasure of creating and working with multiple different platforms built on containers. Each platform has evolved in step with current ecosystem around it, and I’ve gotten the chance to really put Docker’s “batteries included, but removable” philosophy to the test.

Here at Iron.io, we have launched over 1 billion user containers in production, not to mention the containers we launch to keep our services running. The massive volume of containers we launch is enough to place great demands upon any platform that we use.

In our search for the right direction for the evolution of our platform, we’ve explored as many tools as possible. The release of Docker 1.9, combined with production-ready Docker Swarm and Docker Networking, brings a lot of value to those wanting to roll their own platforms.

Continue reading “Shepherding Containers”