setup-dotnet/docs/adrs/v2-setup-dotnet.md

V2 setup-dotnet

Date: 2021-02-15 Status: Proposed

Context

• GitHub-hosted Ubuntu and Windows runners have .NET versions pre-installed in system directories, but the v1 version of action installs .NET to user's directory for that runners. It means that action always download and install .NET version even if it is pre-installed and after using the action all pre-installed .NET versions are unavailable. The behavior is different for macOS runners because pre-installation directory matches the one that is used by action. It means action can use pre-installed versions if it exists, which speeds up customer's workflow.

• According to .NET documentation (https://docs.microsoft.com/en-us/dotnet/core/versions/selection), .NET CLI will use the latest installed .NET SDK and .NET runtime if there are multiple versions installed side-by-side. It is unclear for customers who expect that .NET specified in the task will be used for their project.

Decision

• Change default location for dotnet installation on Windows and Ubuntu images to the pre-installed versions location. It can be reached by using -InstallDir (or --install-dir for Ubuntu) property for installer scripts: https://docs.microsoft.com/en-us/dotnet/core/tools/dotnet-install-script

• Create global.json file via setup-dotnet to specify installed dotnet version as current

v2-preview

There will be a v2-preview branch that will be created for development and testing. Any changes will first be merged into v2-preview branch. After a period of testing & verification, the v2-preview branch will be merged into the main branch and a v2 tag will be created. Any GitHub public documentation and starter workflows that mention setup-dotnet will then be updated to use v2 instead of v1.

Consequences

• Users will be able to use pre-installed dotnet versions after using setup-dotnet task on Windows and Ubuntu runners.
• The current dotnet version will be forced to version that user points in the task.