Digger works best as a 2-piece solution: You can however stil use the most basic features of Digger as a standalone action without a backend. To do that, set the following option in your workflow configuration: 
no-backend: true
You’d also need to add pull_request and issue_comment workflow triggers: 
on:
  pull_request:
    branches: [ "main" ]
    types: [ opened, synchronize ]
  issue_comment:
    types: [created]
  workflow_dispatch:

​
Limitations

Historically this was the original way of running Digger. The initial version called “tfrun” didn’t have any backend, it was just a GitHub action. But it quickly became apparent that without some sort of orchestration there’s only so much that can be done:
  • No concurrency; all plans / applies need to run sequentially, which is slow
  • Action starts on every push or comment, often just to detect that there are no changes. That’s expensive, especially in large repos.
  • Clashing applies from other jobs will fail as they cannot be queued
  • Buckets / tables for PR-level locks need to be configured manually in your cloud account
  • Comments and status checks will be updated with a delay