Always single layer? No caching?

[julioct]

I could not find official info on this, so want to confirm:

Do SDK Container Builds always add a single additional layer for my application on top of the base image?

Seems like regardless of me only changing NuGet dependencies, only changing static files, or only changing code, I always get a single new layer in the image, as opposed to multiple layers that could be cached as it would be the case with a Dockerfile.

An example of what I see when inspecting the layers:

I always see a 9th layer there, regardless of any change I make to my ASP.NET Core project.

[baronfel]

Correct - you always get a single layer with all application assets.

We've definitely thought about using more layers for various kinds of dependencies:

• Nuget package runtime​ assets
• Static web assets
• Assets from other projects
• Etc

But unfortunately there's work that would need to be done in the .NET SDK itself to surface these categories in a way that's easier for containerization to consume. So we've been focusing more on the usability of the tech so far.

[julioct]

Got it, thank you for the quick reply!

[baronfel]

You're welcome! There might be some improvements here as we tackle any of these issues related to MSBuild incrementality in the containers targets - broadly speaking Docker wants layers for the same reason that MSBuild wants incrementality - to determine if any actual work needs to be done, and if not to re-use an old result. So we might find an answer to some of the same shared problems.