The creator of Kel, a devops-focused PaaS for Web applications has released an open source edition of its platform.
Kel is based on the container-cluster management system Kubernetes and was originally made to run Gondor, a managed host for Python and Django apps. Eldarion, the company behind Gondor, hopes Kel will appeal to developers who want a PaaS that's built with workflow in mind, not just app deployment.
Workflow is king
According to James Tauber, co-founder and CEO of Eldarion, Kel's big distinction from other PaaSes is its focus on how developers work across the lifecycle of an application: development, QA, testing, staging, and production.
Like Gondor before it, Kel assumes people who work on a project have various responsibilities and capabilities that must be kept separate, but also need to interoperate occasionally. Tauber cited the example of a developer pulling a production database into an instance to demonstrate a feature, so as to use live data in the demo.
None of Kel's features are held back from the open source edition. The main benefits of the commercial version, Tauber explained, would be providing enterprise services.
K for Kubernetes
Brian Rosner, chief architect at Eldarion, described how Kel uses a two-layer structure to achieve its goals. The bottom layer, or "layer 0," is the Kubernetes cluster outfitted with Kel-specific configuration tools. Above it, on "layer 1," are the application lifecycle workflow tools. Kel allows the use of most any version control system, so those running, say, Mercurial instead of Git aren't at a disadvantage.
As Rosner described it, Kel uses Kubernetes for several reasons: Its feature set and primitives were a good fit for what Eldarion was trying to achieve; it obviated the need for the Kel team to roll their own cluster management; and it "forces a decoupling of the application from the host." This last reason makes it easier to freely move around the database and application servers for a given app across a cluster.
For Eldarion, open-sourcing Kel has a twofold benefit. Of course, it gets the technology in front of a broader audience that may be hungry for it. But it also draws a community to help expand Kel to support other languages and frameworks -- such as Node.js, for which work is already under way.