.NET 9 container images no longer install zlib
.NET 9 container images no longer install zlib since it's not a dependency of the .NET Runtime anymore.
Previous behavior
In previous .NET versions, .NET container images installed the latest version of the zlib package from the Linux base image package repositories.
New behavior
Starting in .NET 9, container images no longer install zlib. In addition, zlib is no longer updated in images where it's already installed from the base image.
Version introduced
.NET 9 Preview 7
Type of change
This change is a behavioral change.
Reason for change
In .NET 9, the Runtime contains a statically linked version of zlib-ng. As a result, the .NET Runtime no longer has a package dependency on zlib. To reduce .NET container image sizes, .NET 9 container images no longer install zlib, and no longer update zlib in images where it's already installed from the base Linux image.
Recommended action
For most scenarios, no action is required. If your containerized .NET app has a direct package dependency on zlib, you should manually install it in your Dockerfile using the package manager.
Affected APIs
None.
