Last year was a good one for Docker, the open-source app containerization startup that helps applications run efficiently in any on-premises or cloud environment, no matter the runtime.
Docker rode a wave of hype all the way to the project's 1.0 stable release in June 2014, timed to coincide with the first-ever DockerCon in San Francisco for the growing Docker community.
During the year, the company announced a series of partnerships and integrations with the likes of Microsoft, Red Hat, Google, Amazon Web Services and VMware. By year's end, Docker claimed that more than 71,379 apps were Docker-ready.
Mostly ready
Docker's momentum seems unstoppable, and that perception is reinforced by a recent Gartner report indicating that the still very young technology is mostly ready for the enterprise -- but note the emphasis on mostly.
But the world of containers doesn't end with Docker.
For starters, getting Docker ready to run in a production environment requires helping hands from the larger ecosystem. An app that's packaged up in a Docker container is great for portability, but it's essentially just sitting there. Replication, scalability, resiliency and security all require help from tools from other companies.
The competition among companies hoping to ride Docker's coattails is fierce. That same Gartner report highlights SELinux and AppArmor as additional security layers that any IT operation looking to go the Docker route should consider. Asigra has launched a dedicated backup solution for containers. Google Compute Engine, Amazon Web Services, and Microsoft Azure are all tripping over themselves to prove that they have the most robust native tools for managing, scaling, scheduling or updating Docker containers. (Google, which has used its own Linux container technology in its data centers for years, has embraced the Docker community by handing over the source code to Kubernetes, its container management project.)
Name a feature, a requirement, a tool set or an application and somebody in the Docker ecosystem is likely working on it already.
Losing focus?
But there's trouble in app container paradise: Docker doesn't want others in the ecosystem to eat its lunch, at least not entirely. The company has been making moves of its own to build out its platform, with more container orchestration and management features. This has drawn criticism from the containerization community, which believes that Docker-the-company is ignoring the lightweight nature of Docker-the-project that made it successful in the first place. Docker, in other words, needs to fit into existing toolchains and not become yet another series of moving parts.
In fact, Docker experienced a major embarrassment in late 2014 when the popular, ultra-lightweight Linux kernel startup CoreOS -- which had been very vocal in its support for the platform -- charged that Docker was losing its focus and released Rocket, its own container runtime.
Docker's response -- in which the company said it disagreed with the "questionable rhetoric" of the Rocket announcement -- was not terribly classy, and only gave more credence to CoreOS's arguments.
Docker's claim to fame is making containers easier and more efficient, not inventing the wheel: Linux Containers (LXC) have been part of the Linux kernel since 2008, and you can trace their lineage back even further to technologies like OpenVZ and Solaris Containers, or even back to 1979 and the chroot command.
The lesson is that Rocket may be the first major alternative container since Docker reinvigorated the concept, but it's not going to be the last, and there's nothing stopping anybody else from developing its own spin on the concept.
Virtual needs
It's important to remember that Docker isn't great for every use case. VMware, which sells virtualization software, and Docker, which can greatly reduce the number of virtual machines you need, might seem like odd partners, but consider this: Docker shines when it's used to package newer apps that will run across various environments, but not every app is going to be well suited for the task.
For example, despite Microsoft's commitment to working with the Docker community, Windows apps aren't terribly efficient in a Docker environment and require workarounds.
In other words, VMware and companies like it still have roles to play. There will be a place for virtual machines in most data centers for a long time to come, even as Docker and containers like it offer a path to doing more with less. (Some, like Joyent, offer tools to manage VMware/container hybrid environments.)
Even if companies decide containers are for them, there's a lot more to containerization than Docker.
This story, "The world of containers doesn't end with Docker" was originally published by Computerworld.