---
name: rushstack-best-practices
description: Provides best practices and guidance for working with Rush monorepos. Use when the user is working in a Rush-based repository, asks about Rush commands…
---

# rushstack-best-practices

Provides best practices and guidance for working with Rush monorepos. Use when the user is working in a Rush-based repository, asks about Rush commands…

# rushstack-best-practicesby microsoft
Provides best practices and guidance for working with Rush monorepos. Use when the user is working in a Rush-based repository, asks about Rush commands…

`npx skills add https://github.com/microsoft/rushstack --skill rushstack-best-practices`Download ZIPGitHub

## Rushstack Best Practices

This skill provides essential best practices for working with Rush monorepos. Following these guidelines ensures efficient dependency management, optimal build performance, and proper command usage.

## Important Guidelines

When encountering unclear issues or questions:

* Never make assumptions - If unsure about Rush behavior, configuration, or commands

* Search official resources first - Check documentation and existing issues before guessing

* Provide accurate information - Base responses on verified sources, not assumptions

* Ask for clarification - When the problem description is ambiguous or incomplete

## Core Principles

* Always use Rush commands - Avoid npm/pnpm/yarn directly in a Rush monorepo

* Use rushx for single projects - Like npm run, but Rush-aware

* rush install vs update - install for CI, update after changes

* rush build vs rebuild - build for incremental, rebuild for clean

* Projects at 2 levels - Standard: apps/, libraries/, tools/

* Selection flags reduce scope - Use --to, --from, --impacted-by

* Build cache is automatic - Configure output folders to enable

* Subspace for large repos - Isolate dependencies when needed

## Project Selection Best Practices

When running commands like `install`, `update`, `build`, `rebuild`, etc., by default all projects under the entire repository are processed. Use these selection flags to improve efficiency:

### --to

Select specified project and all its dependencies.

* Build specific project and its dependencies

* Ensure complete dependency chain build

```
`rush build --to @my-company/my-project
rush build --to my-project # If project name is unique
rush build --to . # Use current directory's project
`
```

### --to-except

Select all dependencies of specified project, but not the project itself.

* Update project dependencies without processing project itself

* Pre-build dependencies

```
`rush build --to-except @my-company/my-project
`
```

### --from

Select specified project and all its downstream dependencies.

* Validate changes' impact on downstream projects

* Build all projects affected by specific project

```
`rush build --from @my-company/my-library
`
```

### --impacted-by

Select projects that might be affected by specified project changes, excluding dependencies.

* Quick test of project change impacts

* Use when dependency status is already correct

```
`rush build --impacted-by @my-company/my-library
`
```

### --impacted-by-except

Similar to `--impacted-by`, but excludes specified project itself.

* Project itself has been manually built

* Only need to test downstream impacts

```
`rush build --impacted-by-except @my-company/my-library
`
```

### --only

Only select specified project, completely ignore dependency relationships.

* Dependency status is known to be correct

* Combine with other selection parameters

```
`rush build --only @my-company/my-project
rush build --impacted-by projectA --only projectB
`
```

## Command Usage Guidelines

### Command Tool Selection

Choose the correct command tool based on different scenarios:

*
`rush` command - Execute operations affecting the entire repository or multiple projects

* Strict parameter validation and documentation

* Support for global and batch commands

* Suitable for standardized workflows

* Use cases: Dependency installation, building, publishing

*
`rushx` command - Execute specific scripts for a single project

* Similar to `npm run` or `pnpm run`

* Uses Rush version selector for toolchain consistency

* Prepares shell environment based on Rush configuration

* Use cases: Running project-specific build scripts, tests, dev servers

*
`rush-pnpm` command - Replace direct use of pnpm in Rush repository

* Sets correct PNPM workspace context

* Supports Rush-specific enhancements

* Provides compatibility checks with Rush

* Use cases: When direct PNPM commands are needed

### Install vs Update

CommandBehaviorWhen to Use`rush update`Updates shrinkwrap, installs new dependenciesAfter cloning, after git pull, after modifying package.json`rush install`Read-only install from existing shrinkwrapCI/CD pipelines, ensuring version consistency

### Build vs Rebuild

CommandBehaviorWhen to Use`rush build`Incremental build, only changed projectsDaily development, quick validation`rush rebuild`Clean build all projectsComplete rebuild needed, investigating issues

## Dependency Management

### Package Manager Selection

Choose in `rush.json`:

```
`{
"pnpmVersion": "8.x.x" // Preferred - efficient, strict
// "npmVersion": "8.x.x" // Alternative
// "yarnVersion": "1.x.x" // Alternative
}
`
```

### Version Constraints

Configure in `common/config/subspaces/<subspace>/common-versions.json`:

```
`{
"preferredVersions": {
"react": "17.0.2",
"typescript": "~4.5.0"
},
"implicitlyPreferredVersions": true,
"allowedAlternativeVersions": {
"typescript": ["~4.5.0", "~4.6.0"]
}
}
`
```

### Adding/Removing Dependencies

Always use Rush commands, not npm/pnpm directly:

```
`rush add -p lodash --dev # Add dev dependency
rush add -p react --exact # Add exact version
rush remove -p lodash # Remove dependency
`
```

## Build Cache Configuration

Configure in `<project>/config/rush-project.json`:

```
`{
"operationSettings": [
{
"operationName": "build",
"outputFolderNames": ["lib", "dist"],
"disableBuildCacheForOperation": false,
"dependsOnEnvVars": ["MY_ENV_VAR"]
}
]
}
`
```

Cache Behavior:

* Cache stored in `common/temp/build-cache`

* Invalidated by: source changes, dependency changes, env vars, command params

* Parallel builds supported via `enableParallelism`

## Troubleshooting

### Dependency Issues

* Avoid `npm`, `pnpm`, `yarn` - use Rush commands

* Run `rush purge` to clean environment

* Run `rush update --recheck` to force dependency check

### Build Issues

* Use `rush rebuild` to skip cache

* Check `rushx build` output for specific errors

* Use `--verbose` for detailed logs

### Performance Issues

* Use selection flags (`--to`, `--from`, etc.) to reduce scope

* Enable build cache in rush-project.json

* Consider subspace for very large monorepos

## Subspace for Large Monorepos

What is Subspace:

* Allows multiple PNPM lock files in one Rush monorepo

* Enables independent dependency management per team/project group

* Reduces risk from dependency updates

* Improves install/update performance

When to Use:

* Large monorepos (50+ projects)

* Multiple teams with different dependency needs

* Conflicting version requirements

* Need for faster dependency operations

## Official Resources

### Documentation & References

Official Websites:

* RushStack.io - Main documentation site

* Rush.js.io - Rush build orchestrator documentation

* Heft.rushstack.io - Heft build tool documentation

* API Extractor - API documentation and rollups

Search Existing Issues:

* Before creating new issues, search rush-stack-builds issues

### When to Search vs. Ask

Search these resources first when:

* Encountering error messages

* Unsure about configuration options

* Looking for examples or tutorials

* Need to understand Rush behavior

Ask the user for clarification when:

* The specific use case is unclear

* Multiple approaches are possible

* Context is missing to provide accurate guidance

* The issue might be environment-specific

## Detailed References

For expanded information on specific domains, see:

* `references/core-commands.md` - Detailed command reference

* `references/project-configuration.md` - Configuration file specifications

* `references/dependency-management.md` - Advanced dependency patterns

* `references/build-system.md` - Build optimization and caching

* `references/subspace.md` - Subspace setup and usage

## More skills from microsoft
oss-growthby microsoftOSS growth hacker personapr-description-skillby microsoftTrigger this skill on any of the following intents:python-architectureby microsoftPython architect personasupply-chain-securityby microsoftSupply chain security expert personaskill-nameby microsoftDescription of what the skill does and when to use itwork-iterationsby microsoftList, create, and assign iterations for Azure DevOps projects and teams.djangoby microsoftBest practices for Django web development including models, views, templates, and testing.flaskby microsoftBest practices for Flask web development including routing, blueprints, and testing.

---

**Source**: https://github.com/microsoft/rushstack/tree/HEAD/skills/rushstack-best-practices
**Author**: microsoft
**Discovered via**: mcpservers.org