What Is PaaS?
How Platform as a Service Works
What is PaaS? It is a cloud model, short for platform as a service, that gives developers a ready-made environment for building, running and scaling applications. You supply your code or container image, and the platform handles the servers, operating system, language runtime and scaling.
The provider manages the infrastructure, the operating system and the runtime for a language such as Node.js, Python, Java or PHP. Developers push code from a Git repository or a command-line tool, and the platform builds and starts the application. When traffic grows, many platforms add more instances automatically, or let you set a rule for doing so.
Buildpacks, Add-Ons and Other Platform Features
Many PaaS products include features that reduce operations work:
- Buildpacks detect the language of your project and turn its source code into a runnable package, so you do not have to write the build steps yourself.
- Add-ons (also called managed services) attach databases, caches, email delivery and logging to your application. The platform provisions and maintains them.
- Deployment tools, such as rolling updates and rollbacks, let you release changes with less manual work.
Heroku, Google App Engine, Azure App Service and AWS Elastic Beanstalk are examples of PaaS products. Each supports a different set of languages and services.
The Trade-Off Between Convenience and Control
PaaS removes a lot of operational work, but it also limits what you can change. You generally cannot choose the operating system version, install software at the system level or tune the network the way you can on IaaS. Platforms also set limits on request duration, memory and background processes. Some applications fit these limits well, while others need more control than a platform allows.
Moving away from a PaaS can be harder than moving a plain server, because the application may depend on platform-specific services. This is one form of vendor lock-in. The backend as a service model carries a similar trade-off, and serverless computing takes the idea of a fully managed runtime further.
Frequently asked questions
Is PaaS the same as a web hosting plan?
Not exactly. A traditional web hosting plan usually gives you an account or server with a control panel, and you manage the site and its updates. PaaS gives you a platform for running your application, often with automatic scaling, deployment pipelines and managed databases. Some hosting providers offer PaaS-style services, but the two categories overlap only partly.
Do I still manage servers with PaaS?
Usually not at the operating system level. You still make decisions about application design, configuration, scaling limits, data, security settings and costs. The provider handles the underlying servers, patches and platform updates, but it does not write your application or protect your data for you.