mirror of
https://github.com/oven-sh/bun
synced 2026-02-02 15:08:46 +00:00
221 lines
8.4 KiB
Plaintext
221 lines
8.4 KiB
Plaintext
---
|
|
title: "Isolated installs"
|
|
description: "Strict dependency isolation similar to pnpm's approach"
|
|
---
|
|
|
|
Bun provides an alternative package installation strategy called **isolated installs** that creates strict dependency isolation similar to pnpm's approach. This mode prevents phantom dependencies and ensures reproducible, deterministic builds.
|
|
|
|
This is the default installation strategy for **new** workspace/monorepo projects (with `configVersion = 1` in the lockfile). Existing projects continue using hoisted installs unless explicitly configured.
|
|
|
|
## What are isolated installs?
|
|
|
|
Isolated installs create a non-hoisted dependency structure where packages can only access their explicitly declared dependencies. This differs from the traditional "hoisted" installation strategy used by npm and Yarn, where dependencies are flattened into a shared `node_modules` directory.
|
|
|
|
### Key benefits
|
|
|
|
- **Prevents phantom dependencies** — Packages cannot accidentally import dependencies they haven't declared
|
|
- **Deterministic resolution** — Same dependency tree regardless of what else is installed
|
|
- **Better for monorepos** — Workspace isolation prevents cross-contamination between packages
|
|
- **Reproducible builds** — More predictable resolution behavior across environments
|
|
|
|
## Using isolated installs
|
|
|
|
### Command line
|
|
|
|
Use the `--linker` flag to specify the installation strategy:
|
|
|
|
```bash terminal icon="terminal"
|
|
# Use isolated installs
|
|
bun install --linker isolated
|
|
|
|
# Use traditional hoisted installs
|
|
bun install --linker hoisted
|
|
```
|
|
|
|
### Configuration file
|
|
|
|
Set the default linker strategy in your `bunfig.toml` or globally in `$HOME/.bunfig.toml`:
|
|
|
|
```toml bunfig.toml icon="settings"
|
|
[install]
|
|
linker = "isolated"
|
|
```
|
|
|
|
### Default behavior
|
|
|
|
The default linker strategy depends on your project's lockfile `configVersion`:
|
|
|
|
| `configVersion` | Using workspaces? | Default Linker |
|
|
| --------------- | ----------------- | -------------- |
|
|
| `1` | ✅ | `isolated` |
|
|
| `1` | ❌ | `hoisted` |
|
|
| `0` | ✅ | `hoisted` |
|
|
| `0` | ❌ | `hoisted` |
|
|
|
|
**New projects**: Default to `configVersion = 1`. In workspaces, v1 uses the isolated linker by default; otherwise it uses hoisted linking.
|
|
|
|
**Existing Bun projects (made pre-v1.3.2)**: If your existing lockfile doesn't have a version yet, Bun sets `configVersion = 0` when you run `bun install`, preserving the previous hoisted linker default.
|
|
|
|
**Migrations from other package managers**:
|
|
|
|
- From pnpm: `configVersion = 1` (using isolated installs in workspaces)
|
|
- From npm or yarn: `configVersion = 0` (using hoisted installs)
|
|
|
|
You can override the default behavior by explicitly specifying the `--linker` flag or setting it in your configuration file.
|
|
|
|
## How isolated installs work
|
|
|
|
### Directory structure
|
|
|
|
Instead of hoisting dependencies, isolated installs create a two-tier structure:
|
|
|
|
```bash tree layout of node_modules icon="list-tree"
|
|
node_modules/
|
|
├── .bun/ # Central package store
|
|
│ ├── package@1.0.0/ # Versioned package installations
|
|
│ │ └── node_modules/
|
|
│ │ └── package/ # Actual package files
|
|
│ ├── @scope+package@2.1.0/ # Scoped packages (+ replaces /)
|
|
│ │ └── node_modules/
|
|
│ │ └── @scope/
|
|
│ │ └── package/
|
|
│ └── ...
|
|
└── package-name -> .bun/package@1.0.0/node_modules/package # Symlinks
|
|
```
|
|
|
|
### Resolution algorithm
|
|
|
|
1. **Central store** — All packages are installed in `node_modules/.bun/package@version/` directories
|
|
2. **Symlinks** — Top-level `node_modules` contains symlinks pointing to the central store
|
|
3. **Peer resolution** — Complex peer dependencies create specialized directory names
|
|
4. **Deduplication** — Packages with identical package IDs and peer dependency sets are shared
|
|
|
|
### Workspace handling
|
|
|
|
In monorepos, workspace dependencies are handled specially:
|
|
|
|
- **Workspace packages** — Symlinked directly to their source directories, not the store
|
|
- **Workspace dependencies** — Can access other workspace packages in the monorepo
|
|
- **External dependencies** — Installed in the isolated store with proper isolation
|
|
|
|
## Comparison with hoisted installs
|
|
|
|
| Aspect | Hoisted (npm/Yarn) | Isolated (pnpm-like) |
|
|
| ------------------------- | ------------------------------------------ | --------------------------------------- |
|
|
| **Dependency access** | Packages can access any hoisted dependency | Packages only see declared dependencies |
|
|
| **Phantom dependencies** | ❌ Possible | ✅ Prevented |
|
|
| **Disk usage** | ✅ Lower (shared installs) | ✅ Similar (uses symlinks) |
|
|
| **Determinism** | ❌ Less deterministic | ✅ More deterministic |
|
|
| **Node.js compatibility** | ✅ Standard behavior | ✅ Compatible via symlinks |
|
|
| **Best for** | Single projects, legacy code | Monorepos, strict dependency management |
|
|
|
|
## Advanced features
|
|
|
|
### Peer dependency handling
|
|
|
|
Isolated installs handle peer dependencies through sophisticated resolution:
|
|
|
|
```bash tree layout of node_modules icon="list-tree"
|
|
# Package with peer dependencies creates specialized paths
|
|
node_modules/.bun/package@1.0.0_react@18.2.0/
|
|
```
|
|
|
|
The directory name encodes both the package version and its peer dependency versions, ensuring each unique combination gets its own installation.
|
|
|
|
### Backend strategies
|
|
|
|
Bun uses different file operation strategies for performance:
|
|
|
|
- **Clonefile** (macOS) — Copy-on-write filesystem clones for maximum efficiency
|
|
- **Hardlink** (Linux/Windows) — Hardlinks to save disk space
|
|
- **Copyfile** (fallback) — Full file copies when other methods aren't available
|
|
|
|
### Debugging isolated installs
|
|
|
|
Enable verbose logging to understand the installation process:
|
|
|
|
```bash terminal icon="terminal"
|
|
bun install --linker isolated --verbose
|
|
```
|
|
|
|
This shows:
|
|
|
|
- Store entry creation
|
|
- Symlink operations
|
|
- Peer dependency resolution
|
|
- Deduplication decisions
|
|
|
|
## Troubleshooting
|
|
|
|
### Compatibility issues
|
|
|
|
Some packages may not work correctly with isolated installs due to:
|
|
|
|
- **Hardcoded paths** — Packages that assume a flat `node_modules` structure
|
|
- **Dynamic imports** — Runtime imports that don't follow Node.js resolution
|
|
- **Build tools** — Tools that scan `node_modules` directly
|
|
|
|
If you encounter issues, you can:
|
|
|
|
1. **Switch to hoisted mode** for specific projects:
|
|
|
|
```bash terminal icon="terminal"
|
|
bun install --linker hoisted
|
|
```
|
|
|
|
2. **Report compatibility issues** to help improve isolated install support
|
|
|
|
### Performance considerations
|
|
|
|
- **Install time** — May be slightly slower due to symlink operations
|
|
- **Disk usage** — Similar to hoisted (uses symlinks, not file copies)
|
|
- **Memory usage** — Higher during install due to complex peer resolution
|
|
|
|
## Migration guide
|
|
|
|
### From npm/Yarn
|
|
|
|
```bash terminal icon="terminal"
|
|
# Remove existing node_modules and lockfiles
|
|
rm -rf node_modules package-lock.json yarn.lock
|
|
|
|
# Install with isolated linker
|
|
bun install --linker isolated
|
|
```
|
|
|
|
### From pnpm
|
|
|
|
Isolated installs are conceptually similar to pnpm, so migration should be straightforward:
|
|
|
|
```bash terminal icon="terminal"
|
|
# Remove pnpm files
|
|
rm -rf node_modules pnpm-lock.yaml
|
|
|
|
# Install with Bun's isolated linker
|
|
bun install --linker isolated
|
|
```
|
|
|
|
The main difference is that Bun uses symlinks in `node_modules` while pnpm uses a global store with symlinks.
|
|
|
|
## When to use isolated installs
|
|
|
|
**Use isolated installs when:**
|
|
|
|
- Working in monorepos with multiple packages
|
|
- Strict dependency management is required
|
|
- Preventing phantom dependencies is important
|
|
- Building libraries that need deterministic dependencies
|
|
|
|
**Use hoisted installs when:**
|
|
|
|
- Working with legacy code that assumes flat `node_modules`
|
|
- Compatibility with existing build tools is required
|
|
- Working in environments where symlinks aren't well supported
|
|
- You prefer the simpler traditional npm behavior
|
|
|
|
## Related documentation
|
|
|
|
- [Package manager > Workspaces](/pm/workspaces) — Monorepo workspace management
|
|
- [Package manager > Lockfile](/pm/lockfile) — Understanding Bun's lockfile format
|
|
- [CLI > install](/pm/cli/install) — Complete `bun install` command reference
|