Why ought I not to install Visual Studio on my CI server? - visual-studio

Question

A lot of people new to CI (Continuous Integration) install VS (Visual Studio) on their CI server "because it is required to compile the code". MSTest is a common reference brought up here.
Why should I not install VS (or generally speaking, any software not out-of-the-box) on my CI server?
(This question has not been asked before apparently, so I'm adding it for reference. If it already exists, sorry, I missed it, please merge. If no answer is provided to this question within some time I can add one myself)

Answer 1

Because you don't need to. A Visual Studio license is pretty expensive, so having one just lying around on a server where no one's using it is just a waste.There are a couple of arguments why you would still need to install a full blown Visual Studio instance on your Continuous Integration server - but here are their counter arguments:
Reason 1: I need it to compile.
Reality: No, you don't. You need MSBuild to compile, but that is available for free, in the Windows SDK. Note that there are several versions for different operative systems and .NET versions, so be careful to download the correct one.
Reason 2: I need it to make quick fixes on the server.
Reality: No, you don't. You shouldn't make quick fixes on the server - you should check out from your version control system, make the fix, build and run tests locally until it works, check in, and have the CI system do the rest for you. That's why you have a CI system.
Reason 3: Without Visual Studio, I can't run MSTest no my CI server.
Reality: Wrong. AFAIK, the MSTest runner is also part of the SDK (at least that's what it seems like on our CI server here - although I can't verify it since we don't have any tests at the moment...). However, a quick googling found this blog post which explains how to do it without the SDK as well. I haven't read through it in detail, so I can't promise that it works, or that it's legal. You have been warned.
Feel free to add more reasons in comments, and I'll counter them.

Answer 2

You might need to install Visual Studio anyway, out of practicality
I was going to try and refute the accepted answer, posted by #TomasLycken, in the comments, but found I needed more space to talk. Even though I technically agree with what #TomasLycken has asserted, here, I'll list some of the dependencies that I found difficult to install on my CI server - and leave it to you to decide how right the accepted answer is...
1 - 'mshtml' primary interop assembly
You can see the problem I was getting in my build output at this S.O. question I created and answered. Mind you, I spent several hours figuring out how get the desired PIA registered - and it was a result of running some .exe's on the server that came from my V.Studio installation - hmmmmmm
CONTEXT: I had a win forms project that used the Web Browser control.. and in the 'WebDocumentCompleted' event, I was casting the DomDocument to hshtml.IHTMLDocument2 .. and that's why I had a reference to Microsoft.mshtml in my project.
RESULT: Now #TomasLycken suggests I deal with this by fixing my code. At first, I wanted to bawk at this suggestion. My code is deployed and working! But, when I do a web search, I see that Microsoft doesn't really recommend using their mshtml PIA outside of the Visual Studio environment they developed it for.
The offending 10 lines of code was effectively doing a little screen-scraping of data on behalf of our users who do research on technical topics in several well-known web portals. But, when I tested this code, written in 2009, it appears that the DOM it once manipulated has now changed in 2016. I know shocking. Probably not my smartest bit of code. Probably time to retire this function - in other words, fix the code and recommit it.
#TomasLyken I think is right on this one.
2 - Win Forms Project post-build script
CONTEXT: So I had come across this cool post-build technique on S.O. that allows my app.config file in my WinForms project to undergo an XDT transform similar to the way my web projects' web.config files are transformed. Well, it just works OOTB, so-to-speak, if you copy from S.O. and into the .csproj or .vbproj source file. But, once you put all this onto a build server with no Visual Studio, the critical piece fails due to a dependency on:
$(MSBuildExtensionsPath)\Microsoft\VisualStudio\v10.0\Web\Microsoft.Web.Publishing.targets
Now this is straightfoward enough to rectify.. I just copied over to the CI server my C:\Program Files (x86)\MSBuild\Microsoft directory. But, should I? Since I've kinda went off the reservation of what Visual Studio normally would support.. one could argue that #TomasLycken's accepted answer is still right on this point, too.
3 - Just getting all the .NET Frameworks and Multi-Targeting Packs in place
Points 1 and 2 above, were actually the last things I conquered in my attempt to get my first build job to run. And my first build job is for a solution stack that I've created and maintained over the past 8 years.. so it has weathered a few frameworks and would have some non-trivial texture to it. I knew it wouldn't be easy. In fact, I hoped by making a CI server that could build this .sln, that it would in fact be ready to build most any other solution we threw at it.
When I first received my clean "Windows 2012 R2" server, it simply had a lot of things missing.. and I'm wondering if I had installed Visual Studio first, if it would have rectified some of these things straight off?
Below is my synopsis of what I had to do - but it doesn't show the pain and suffering involved figuring it all out and the false starts. Maybe it'll help someone else, though.
> First, uninstalled 4.6.1 framework
-- (find Update for Microsoft Windows (KB3102467) and click Uninstall.)
-- also uninstalled anything from MS labeled with C++ redistributable (a later step will restore these)
> Then, install Windows 7 SDK (installs critical "reference assemblies" and a proper baseline 4.0 framework)
-- Then, install Multi-Targeting Pack for Framework 4.0.1 (netfx_401mtpack.exe)
-- Then, install Multi-Targeting Pack for Framework 4.0.3 (netfx_403mtpack.exe)
> Then, reinstalled 4.6.1 framework for 2012 R2 (KB3102467)
> Then, installed Microsoft .NET Framework 4.6.1 Developer Pack (DP461-DevPack-KB3105179-ENU.exe)
> Then, installed "Visual Studio 2015 Build Tools" (BuildTools_Full.exe)
> Downloaded a copy of nuget.exe and put it in the C:\Windows directory
4 - Getting rid of 'missing ruleset' warning MSB3884
From #kevinbosman's post on this GitHub issues thread
If you don't want to edit your Microsoft.CodeAnalysis.Targets file, please note that it is not enough to merely copy the folder C:\Program Files (x86)\Microsoft Visual Studio 14.0\Team Tools\Static Analysis Tools\Rule Sets\ to the build server.
You also need to create the registry key HKEY_LOCAL_MACHINE\SOFTWARE\Wow6432Node\Microsoft\VisualStudio\14.0\Setup\EDev and add the string value StanDir = C:\Program Files (x86)\Microsoft Visual Studio 14.0\Team Tools\Static Analysis Tools\
5 - Getting MSTest to run correctly
Need dlls copied into your build machine, some must register w/GAC more info here specifically:
Microsoft.VisualStudio.QualityTools.Resource.dll
Microsoft.VisualStudio.QualityTools.UnitTestFramework.dll
Need a hive out of your dev machine's registry copied into build server
some warnings, if you want them to go away, according to this Microsoft visual studio help forum require a VS 2010 and feature pack 2 installation.