What's the difference between launching a docker container in App Engine vs Compute Engine?

Question

Given that you can upload docker images to both the app engine and the Compute Engine, what's the real difference for a person that always contains their apps in docker?

According to a similar question the difference boils down to PaaS vs IaaS, but with a docker file you always specify the OS and runtime environment. So the only difference I see is you might end up over specifying on App Engine by giving a container.

Answer 1

Fundamentally, if you just want your app to scale seamlessly and quickly without much input, use App Engine Flex. If you want more control that you can configure in different ways using other Google products, consider an unmanaged instance group with Compute Engine.

Some history

It's worth noting that the ability to add Docker images to Compute Engine instances was an extremely recent development. And before that, App Engine Flexible was the new kid in town because we used to only have App Engine standard which definitely didn't allow you to use Docker as a base.

Key Differences

Here are the key differences in my experience:

• App Engine is designed as a PaaS product and so you can customize scaling parameters in your app.yaml and App Engine reads those and takes over from you. It's technically true that you can do this using Compute Engine but it involves more configuration - you need to set up an instance group, a backend and a frontend. With App Engine, all of that is taken care of for you
• You can't setup any load balancers or any peripheral services or products on top of App Engine. App Engine Flexible went quite a way further to give the user more control and more (sorry) flexibility. However, it doesn't allow unfettered integration with other services. Whereas with Compute Engine, you can setup an HTTPs load balancer, add your machines to different networks and subnets, set custom tags etc...

On an additional note, a more detailed explanation on the difference between App Engine and Compute Engine can be found here .

Answer 2

App Engine is PaaS service and managed service from google. It has options as dynamic instance and resident instance to achieve scaling. It has predefined runtime setup for the supported languages, we just need to execute the code. It supports execution of multiple versions of the applications simultaneously, so we can release the code changes for separate group of users. It's inherently support container environment, so the basic details like number of pods or nodes need no to provide. Even for the App Engine Standard if there is no load than the node count reduced to zero means no cost. App Engine Flexible requires at-least one up instance. Here the deployment can be done by a single command ie gcloud app deploy app.yaml

Compute engine is IaaS so developer needs to create a machine, setup the desired software's, setup the docker container environment. There will be no scaling, version management, traffic control,security, firewall, health monitoring and repair etc. So with compute engine it's really tough to achieve the capabilities provided by App Engine. The batter alternative is Kubernetes Engine.