fluent-bit support windows nano server

[zanejohnson-azure]

Is your feature request related to a problem? Please describe.
Yes, our service uses Fluent Bit to collect logs and provide log insights to customers. While Fluent Bit is lightweight, the Windows Server Core image size is over 5GB. In other words, to run Fluent Bit in a Windows container environment, we need a large image, which does not align with the lightweight goal of Fluent Bit.

Describe the solution you'd like
Microsoft offers a much smaller Windows image, Nano Server, which is less than 300 MB in size. Therefore, if Fluent Bit can support Nano Server, we will have a truly lightweight Fluent Bit for Windows container environments from the perspective of container size.

Describe alternatives you've considered
Currently, there are limited alternatives. Fluent Bit supports Windows Server Core, and the only smaller image available is Nano Server.

Additional context
*** How has this issue affected you? What are you trying to accomplish? ***
As mentioned, using Fluent Bit in a Windows container environment is cumbersome due to the large container size required.

*** Add any other context or screenshots about the feature request here. ***
In this PR #10233, the author analyzed DLL dependencies. Additionally, our team tried to run Fluent Bit on Nano Server but encountered the error fluent-bit exited with code '-1073741515' and performed a DLL dependency analysis. We found that several DLLs that Fluent Bit depends on are not available in Nano Server. See the missing ones in the list below:

[FOUND IN SYSTEM32] bcrypt.dll
[MISSING] NETAPI32.dll
[FOUND IN SYSTEM32] iphlpapi.dll
[MISSING] gdi32.dll
[MISSING] advapi32.dll
[FOUND IN SYSTEM32] wevtapi.dll
[FOUND IN SYSTEM32] CRYPT32.dll
[MISSING] user32.dll
[FOUND IN SYSTEM32] WS2_32.dll
[FOUND IN SYSTEM32] OLEAUT32.dll
[MISSING] SHLWAPI.dll
[MISSING] SHELL32.dll
[MISSING] kernel32.dll
[MISSING] winmm.dll
[MISSING] ole32.dll

[mabrarov]

Hi,

I just want to share information which I collected (using GUI version of https://github.com/lucasg/Dependencies) when I was working on the same task - it can help to understand if some DLLs missing in mcr.microsoft.com/windows/nanoserver:ltsc2022 docker image can be replaced / avoided (I didn't complete this analysis).

DLLs used by Fluent Bit on Windows, but missing in mcr.microsoft.com/windows/nanoserver:ltsc2022 image:

DLL	Used functions	Comment
shlwapi.dll	PathRemoveFileSpecA	Can be replaced with api-ms-win-core-shlwapi-legacy-l1-1-0.dll?
shlwapi.dll	PathIsDirectoryA
shlwapi.dll	PathMatchSpecA	Can be replaced with api-ms-win-core-shlwapi-legacy-l1-1-0.dll?
shell32.dll	SHCreateDirectoryExA
advapi32.dll	many	Can be replaced with advapi32legacy.dll and advapi32res.dll?
netapi32.dll	NetApiBufferFree
netapi32.dll	NetWkstaGetInfo
ole32.dll	CoInitializeEx	Can be replaced with api-ms-win-downlevel-ole32-l1-1-1.dll?
ole32.dll	CoSetProxyBlanket	Can be replaced with api-ms-win-downlevel-ole32-l1-1-1.dll?
ole32.dll	CoCreateInstance	Can be replaced with api-ms-win-downlevel-ole32-l1-1-1.dll?
ole32.dll	CoUninitialize	Can be replaced with api-ms-win-downlevel-ole32-l1-1-1.dll?
ole32.dll	CoTaskMemFree	Can be replaced with api-ms-win-downlevel-ole32-l1-1-1.dll?
ole32.dll	StringFromCLSID	Can be replaced with api-ms-win-downlevel-ole32-l1-1-1.dll?
ole32.dll	CoInitializeSecurity	Can be replaced with api-ms-win-downlevel-ole32-l1-1-1.dll?

Outdated, but seems to be still useful and correct information:

1. Nano Server APIs (DLLs) - https://learn.microsoft.com/en-us/previous-versions/windows/desktop/legacy/mt588480(v=vs.85)
2. DLLs Included with Server Core - https://learn.microsoft.com/en-us/previous-versions/windows/desktop/legacy/ee391643(v%3Dvs.85)

Thank you.

[patrick-stephens]

I guess we could do a multi-stage build to bring in the missing DLLs from the larger image to the smaller one as a base then add FB on top, similar to what we do for the Linux side. It seems a little brittle but potentially worth it for the humongous image sizes that Windows containers seem to be.

[mabrarov]

Hi @patrick-stephens,

IMHO, copying missing DLLs (from Windows Server Core image into image based on Windows Nano Server) can be insufficient (but I vote for a try), because they may need Windows services and APIs (other DLLs and services) which are missing in Nano Server (that's why it's smaller than Windows Server Core).

I'd be more focused (if have time) into replacement (avoiding) some Windows APIs (functions), like functions from shlwapi.dll and shell32.dll.

Please note also that, if I remember it correctly (sorry, I failed to find respective documentation, so please don't trust me blindly), there can be some "aliasing" for (well-known) DLLs of Windows APIs, which means that if, for example, advapi32.dll file is missing in mcr.microsoft.com/windows/nanoserver:ltsc2022, then it doesn't mean that application linked with advapi32.dll will fail on mcr.microsoft.com/windows/nanoserver:ltsc2022 - the "aliasing" can map advapi32.dll file to (just an example) advapi32legacy.dll file. I tried to run CLI tool from https://github.com/lucasg/Dependencies (which handles this kind of aliasing correctly) inside container based on mcr.microsoft.com/windows/nanoserver:ltsc2022, but that CLI tool also needs some DLLs which are missing in mcr.microsoft.com/windows/nanoserver:ltsc2022, i.e. that tool can not run in mcr.microsoft.com/windows/nanoserver:ltsc2022 too.

Sorry, if these notes don't help and thank you for your work on FB.

[patrick-stephens]

Yeah I'd rather not spend time figuring it out as I don't know enough 😅

It would be good to get contribution from someone who does and needs this.

[cosmo0920]

In the spec table, we need to replace PathIsDirectoryA and SHCreateDirectoryExA at least.
There is no listed APIs for those APIs in the link of Nano Server API page.

[cosmo0920]

However, nano-scan-api does not point out any incompatibilities:

$ENV:HOME\Documents\GitHub\nano-api-scan [master ≡]> .\nano-api-scan\bin\Release\netcoreapp3.1\nano-api-scan.exe $ENV:HOME\Documents\GitHub\fluent-bit\build\bin\fluent-bit.dll
-----------------------------------------------------------------------------
=== fluent-bit.dll ===
=== $ENV:HOME\AppData\Local\Temp\nano-api-scan\2b08be4a-3c1a-476b-a46f-cc90cf47c85c\fluent-bit.dll ===

[cosmo0920]

netapi32.dll NetApiBufferFree
netapi32.dll NetWkstaGetInfo

This can be included as:
https://learn.microsoft.com/en-us/previous-versions/windows/desktop/legacy/mt588480(v=vs.85)#netapi32dll

[cosmo0920]

Plus, we need to link the traditional dlls like kernel32.dll, user32.dll, gd32.dll, ....
Instead, we need to link oncore.dll and other umbrella libraries to replace with the actuall calling APIs from the traditional ones.

ref: https://learn.microsoft.com/en-us/windows/win32/apiindex/windows-umbrella-libraries

[cosmo0920]

I found that to link Nano Server dll/lib correctly, we need to update the definitions of default libs:
https://gitlab.kitware.com/cmake/cmake/-/blob/master/Modules/Platform/Windows-MSVC.cmake#L256

"kernel32.lib user32.lib gdi32.lib winspool.lib shell32.lib ole32.lib oleaut32.lib uuid.lib comdlg32.lib advapi32.lib"

This line is included in cmake itself. So, we need to process inside of CMake to support to link Nano server compatible lib/dll.