September 23, 2017

Would Docker be so popular if it wasn’t open source? That’s a question worth pondering if you want to understand just what has made Docker so successful.

To be clear, cost is not the issue at stake here. A non-open-source Docker might also cost money, but that is a separate issue. There are plenty of closed-source software platforms that do not cost money. Some open-source platforms do cost money.

What I am instead interested in thinking about is the extent to which Docker would have become as successful as it has without its code being open source.

How Open Source Has Helped Docker

In many ways, it’s hard to imagine Docker having been as remotely successful if it weren’t an open-source platform. There are several reasons for this:

  • Docker is deeply integrated at a technical level with the Linux kernel. (Docker on Windows in a different story, but that is a newer platform.) Linux server administrators tend not to like running “binary blobs” on their servers, especially when those blogs interact at a low level with the kernel. If Docker were closed-source, it would likely have enjoyed a much weaker reception among Linux folks.
  • Docker needed the community’s help to build a complete platform. At first, Docker’s main product was the engine that powered Docker containers. Docker has since built out its ecosystem with Swarm, Docker Hub and other tools. But the Docker container world would be much less dynamic if projects and organizations such as Kubernetes, CoreOS and the CNCF were not helping to create key tools and standards for containers.
  • Docker’s main competitor in many senses is VMware. Docker’s open-source nature gave Docker a selling point over VMware. On balance, this is probably not the main reason why many organizations switched to Docker. But it helped make Docker a more compelling choice than VMware for companies that were tired of running their infrastructure on closed-source, proprietary technology that raised vendor lock-in threats. (That said, those companies could also have switched to KVM, an open source alternative to VMware, of course.)
  • By the time Docker was born in 2013, open source had become (or was close to becoming) the default way to build and distribute software. In this regard, Docker would have seemed less forward-thinking if it had been a closed-source platform. It would have reminded people of the 1990s, when open source software (and free software) remained a radical idea to many people, more than of the future.

But Maybe Docker Didn’t Need to be Open Source…

On the other hand, you could make the case that Docker is such a powerful technology that it would have succeeded even if its source code weren’t open. The ability of Docker containers to provide environment consistency through all stages of software deliver is a major advantage, and it doesn’t depend on Docker’s being open or not.

In addition, Docker has a history of not playing completely nicely with the open-source community. Docker was accused in earlier years of skirting efforts to build community standards for containers in favor of pushing its own platform forward. (That has changed; Docker is now firmly committed to open standards.) And some Docker tools, such as Docker Security Scanning, are closed source.


All in all, though, it is hard to imagine Docker having become so successful without being open source. Docker might have found some success as a closed-source platform, but it would have enjoyed the explosive popularity and influence that it claims today.

Christopher Tozzi

Christopher Tozzi has covered technology and business news for nearly a decade, specializing in open source, containers, big data, networking and security. He is currently Senior Editor and DevOps Analyst with and