[WIP] [GSoC 2026 PoC] GCP Cloud Run Plugin for PipedV1

[zyzzmohit]

Description

This is a Draft PR showcasing a 60-70% functional prototype of the GCP Cloud Run Plugin for PipedV1. I have built this as a Proof of Concept (PoC) for my GSoC 2026 Proposal (Issue #6114).

By building this prototype, I wanted to rigorously validate my understanding of the new piped-plugin-sdk-go boundaries, prove that the API interactions can be cleanly decoupled into the gRPC plugin architecture, and ensure my proposal's timeline is highly realistic.

What is implemented in this PoC:

1. Platform Provider: Created a specialized API client wrapping the GCP run/v1 API with native authentication support, and successfully ported the unstructured Knative YAML parsing into provider/manifest.go to cleanly decouple from v0 logic.
2. Version Determination: Extracted image tags dynamically, natively incorporating my previous patch for advanced registry path parsing from PR bug(cloudrun): fix parseContainerImage to handle images with registry… #6572 directly into the v1 DetermineVersions flow.
3. Execution Dispatching: Wired up ExecuteStage to dynamically detect CLOUDRUN_SYNC from the SDK pipeline configuration and execute an end-to-end quick sync execution (mapping traffic to 100%, commit-suffix revision generation, and Create/Update API safety checks).

The module successfully compiles against the SDK using go build ./.... I do not intend for this PR to be reviewed or merged immediately; it serves strictly as an actionable baseline and architectural proof for my GSoC 2026 mentorship application.