[stickfigure]

Docker means you're maintaining an operating system, watching out for security vulnerabilities, patching software. It's still work, and if you screw it up, you're hosed.

If you're on Heroku or Google App Engine, you deploy your application code. That's it.

[manigandham]

Docker containers (on Linux) don't have a guest OS. They all share the same kernel and only the userland is different depending on which distro you choose for your base.

You can choose to build on a scratch/blank image just as easily, which means nothing except your app itself is in the image.

[ornornor]

You still have to update the packages or distro your image is based on. It’s not as maintenance free as heroku or google app engine.

[manigandham]

Sure, but you can get the latest image automatically as part of your container build. It's not as hard as it seems.

Or you can build an image from scratch without any distro and then there's nothing to maintain.