msbuild-server

DevOps & Security

Guide for using MSBuild Server to improve CLI build performance. Activate when developers report slow incremental builds from the command line, or when CLI builds are noticeably slower than IDE builds. Covers MSBUILDUSESERVER=1 environment variable for persistent server-based caching. Do not activate for IDE-based builds (Visual Studio already uses a long-lived process).

QUICK START

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Source SKILL.md: https://github.com/dotnet/skills/blob/HEAD/plugins/dotnet-msbuild/skills/msbuild-server/SKILL.md

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MSBuild Server for CLI Caching

Use the MSBuild Server to cache evaluation results across CLI builds, matching the performance advantage Visual Studio gets from its long-lived MSBuild process.

When to Use

Small incremental builds from CLI (dotnet build) are slower than expected
Developers notice that VS builds are faster than CLI builds for the same project
CI agents run many sequential builds of the same repo

When Not to Use

IDE-based builds (Visual Studio already uses a long-lived MSBuild process)
One-off builds where cold-start overhead is acceptable
Build correctness issues are suspected (disable the server to isolate the problem)

Inputs

Input	Required	Description
Shell context	No	The shell where the environment variable will be set (bash, PowerShell, or Windows persistent)

Workflow

Step 1: Confirm CLI context

Verify the developer is building from the command line (dotnet build), not from Visual Studio or another IDE. The MSBuild Server provides no benefit inside an IDE.

Step 2: Set the environment variable

# Bash / CI
export MSBUILDUSESERVER=1

# PowerShell
$env:MSBUILDUSESERVER = "1"

# Windows (persistent)
setx MSBUILDUSESERVER 1

Step 3: Validate improvement

Run two sequential builds of the same project and compare times:

First build (cold): dotnet build -- server starts, no cache benefit
Second build (warm): dotnet build -- should be noticeably faster

The most noticeable improvement is in repos with many projects or complex Directory.Build.props chains.

Validation

MSBUILDUSESERVER=1 is set in the shell
Second sequential build is faster than the first
dotnet build-server shutdown followed by a rebuild confirms the server restarts cleanly

Common Pitfalls

Pitfall	Solution
Expecting improvement in Visual Studio	VS already uses long-lived MSBuild nodes; the server adds no benefit
Build correctness issues after enabling	Run `dotnet build-server shutdown` to reset; if issues persist, disable the server
Server process using unexpected memory	The server persists in background; shut down with `dotnet build-server shutdown` when idle