You’ve heard of platform as a service (PaaS). You’ve heard of containers as a service (CaaS). Wondering what the difference is between a PaaS and a CaaS, and which solution is best for deploying Dockerized applications? If so, this post is for you.
Explaining the differences between a PaaS and a CaaS is important because there tends to be some ambiguity when people discuss these two types of application deployment solutions.
Some people would suggest that a CaaS is a form of PaaS—specifically, one focused on containerized applications.
Others, including Chip Childers of CloudFoundry writing on this blog, view CaaS as a watered-down or less complete version of PaaS.
Differences between PaaS and CaaS
I tend to think of the PaaS vs. CaaS debate in somewhat different terms.
When I hear PaaS, I think of a developer-oriented application delivery solution that integrates programming tools, deployment tools and application hosting into a single package.
A CaaS is different. Most CaaS solutions don’t include development tools. They just provide a complete stack of tools for deploying containers. Those tools include the Docker runtime, a container image registry, an orchestrator and infrastructure to host it all.
So, the point of a CaaS is different from the point of a PaaS. A PaaS is an integrated application development and deployment solution. A CaaS is a turnkey way to deploy Docker containers, which requires you to develop the applications separately.
PaaS vs. CaaS: Which is the Better Choice?
In other words, a PaaS and a CaaS aren’t necessarily different ways to solve the same problem.
True, PaaS and CaaS can blend together in some scenarios. For example, if you use AWS Beanstalk (a PaaS) to develop applications and then deploy them on ECS (which is a CaaS), you’re essentially using a PaaS-CaaS hybrid that provides all of the functionality required to develop and deploy containerized applications on the AWS cloud.
But in most cases, PaaS and CaaS involve distinct use cases. If you want an integrated solution for developing and deploying applications (whether you plan to use containers to host them or not), get a PaaS. If you just want an easy way to set up and manage a Docker environment, get a CaaS.
Is CaaS an Inferior PaaS?
As for the idea that a CaaS is an incomplete version of a PaaS, I don’t think it quite adds up.
Again, a CaaS provides value by offering an easy on-ramp for setting up and running a Docker environment. In contrast, a PaaS caters to a different set of use cases, which involve application development and deployment.
In addition, a PaaS has nothing intrinsically to do with Docker. Some PaaS offerings use Docker containers, but plenty don’t. In contrast, all CaaS platforms have Docker at their core.
So, in most cases, PaaS vs. CaaS is not the right question to ask. Deciding whether you can benefit from a PaaS is a distinct question from deciding whether to use a CaaS, because PaaS and CaaS are very different types of solutions.