The version of "Microsoft.Extensions.Hosting" on NUGET has the following dependencies:
Given that .NET framework 4.8 is the one for long-term support, it seems strange that it is not an option.
Is there a reason for this? Will my application (a Windows service) work if only .NET 4.8 is on the machine?
An immediate problem it is causing is that the bin dir contains 42 Microsoft dlls, which seem to be the items listed under v4.6.2 in NUGET for the package (and a related one).
I don't want to have to distribute all these, and keep them updated!
This is the list of dlls:
I think there are several questions here, and I would normally vote to close the question as needs more focus, however...
If you are targeting .NET Framework 4.8 then that would satisfy the dependency on .NET Framework 4.6.1 as .NET Framework 4.8 is backwards compatible.
You could also write a library targeting .NET Standard 2.0 as .NET Framework 4.8 supports this dependency too. See this learn article on .NET Standard.
"Is there a reason for this?"
Yes, by supporting a lower version of .NET Framework allows the package to be used across more versions of .NET Framework.
"Will my application (a Windows service) work if only .NET 4.8 is on the machine?"
The answer to this is probably going to be yes, but it really depends if your application parts of .NET Framework unique to .NET Framework 4.8.
TLDR: It depends.
"An immediate problem it is causing is that the bin dir contains 42 Microsoft dlls, which seem to be the items listed under v4.6.2 in NUGET for the package (and a related one)."
This is normal, don't worry about it. As I previously mentioned .NET Framework 4.8 is backwards compatible with .NET Framework 4.6.2 and they should get on together absolutely fine.
-"I don't want to have to distribute all these, and keep them updated!"_
Yes, and no...
Yes
You're going to have to distribute these assemblies (dlls) with your application. Again, this is normal and has been since moving away from the GAC in earlier versions of .NET Framework. Besides, it makes deployments much easier by having available the exact version you've built your application against.
No
You won't have to worry about keeping these up to date. They are for your application only and won't affect anything else installed on the machine. They will only get updated if there's an updated version of the package and you update your application to use the updated version. If you update the installed version of your application then it will bring with it the correct versions of these assemblies/dlls that your application depends on. This is another benefit of including the assemblies your application depends on.
TLDR