It might not be obvious, and certainly when I got started with containers, I didn’t realize that there’s side-benefits that are not typically talked about.

You might know the main benefits already,

• Similar to VMs, they provide a consistent runtime environment
• Similar to VMs, they act as a sandbox for applications
• Unlike VMs, they have a small disk footprint
• Unlike VMs, they have a very small overhead

In short, because they are lightweight, they have all the benefits from VMs and they are fast to start. This small difference opens a new world of possibilities.

Extending the Art of the Possible

Since they are fast to start and they are portable, with some work you can run the entire application from the CI/CD pipelines. This opens new possibilities for things that were once much harder to do - running functional tests before deploying anywhere.

In the example above, we run functional smoke tests against a docker compose version of the application, database and all. You can extend this concept to also run penetration tests as I alluded in my previous DevSecOps post.

What’s risky? What fails often? Database changes? API Authentication?

There are things you can probably test with containers without deploying to an environment and spending money on cloud resources.