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Debugging Rego

In addition to being a language server, Regal can act as a Debug Adapter. A Debug Adapter is a long running program that can communicate with a debugger client, such as Visual Studio Code's debugger, to provide live, step-by-step, debugging capabilities for a language.

Animation showing the a debugging session in VS Code

A debugging session in VS Code

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In order to use the Debug Adapter, you must be using Regal v0.27.0 or greater, as well as a compatible client. See Editor Support for more details.

Getting Started​

See the documentation in the Editor Support page for supported clients:

Features​

The Regal Debug Adapter currently supports the following features:

Breakpoints​

Breakpoints allow you to continue execution of a policy until a given point. This can be helpful for:

  • Inspection of variables at a given point in time
  • Seeing how many times a given block of Rego code is executed, if at all
  • Avoiding the need to step through code as it's run line by line
Screenshot of a breakpoint in VS Code

Variable Inspection​

Either at a breakpoint or while stepping through code, you can inspect the local variables in scope as well as the contents of the global input and data documents.

input will be loaded from input.json in the workspace if it exists.

Variables being inspected during execution in VS Code

Print statements are also supported, these are shown in the debug console:

Print statements shown in the debug output console