Fast .NET SDK/Runtime installation for GitHub Actions.

Parallel downloads, automatic caching, and smart version resolution.

- uses: fast-actions/setup-dotnet@v1
  with:
    sdk-version: '10.x'

• Flexible installation: Install SDK, Runtime, and/or ASP.NET Core Runtime
• Parallel downloads: Multiple requested versions download concurrently
• Smart version resolution: Wildcards (10.x, 10.x.x) and keywords (latest, lts, sts)
• Full global.json support: Supports global.json file for SDK version resolution
• Intelligent deduplication: Skip redundant installs when an SDK already includes the requested runtimes
• Automatic caching: Cache the .NET installation directory to speed up subsequent runs
• Conditional installation: Uses pre-installed system .NET when all versions are present
• Non-root installation: Installs to user-writable tool cache without requiring root permissions

# Use latest LTS SDK
- uses: fast-actions/setup-dotnet@v1
  with:
    sdk-version: 'lts'

# Multi-target testing (latest SDK + multiple runtimes)
- uses: fast-actions/setup-dotnet@v1
  with:
    sdk-version: 'latest'
    runtime-version: |
      9.0.0
      8.0.0
      7.0.0

# Runtime-only (no SDK)
- uses: fast-actions/setup-dotnet@v1
  with:
    runtime-version: '8.0.x'

# From global.json
- uses: fast-actions/setup-dotnet@v1

• Wildcards: 10.x is treated as 10.x.x and resolves to the latest matching version
• Keywords: latest, lts, sts resolve via the .NET releases index
• Preview selection for keywords: set allow-preview: true to include preview channels in keyword resolution

• Enabled by default (cache: true)
• Unified cache: One GitHub Actions cache entry per run, keyed by platform, architecture, and a hash of all resolved versions
• Installation directory is checked first; if versions are missing, the unified cache is restored (if present), then each version is installed from cache or downloaded
• Cache key uses resolved versions (not input patterns): if 10.x resolves to a newer patch later, the key changes and the action downloads the new set
• cache-hit is true when all requested versions came from cache, false otherwise

Benchmark Results (ubuntu-latest):

Note: Actual performance depends on various factors including runner specifications and network conditions.

For detailed documentation, advanced features, and more examples, see docs/guide.md.

Check out the Migration Guide for a quick reference on how to switch to this action.

I built this GitHub Action because I care a lot about workflow execution time. The official actions/setup-dotnet works great for most cases, but in my workflows it was consistently slower than I wanted (especially when the runner spends a bunch of time installing multiple SDKs/Runtimes).

I tried to improve the official action first: I opened a PR there, but it ended up being ignored/stalled. Rather than keep waiting, I rebuilt the idea with a different focus: faster installs, better parallelization, and caching.

This isn’t meant to replace the official action for everyone. If you don’t care about shaving minutes off CI, you can stick with actions/setup-dotnet. If you do care about execution time (or you install multiple versions regularly), fast-actions/setup-dotnet is for you.

This project is licensed under the MIT License. See LICENSE.