fix(control-plane): default BackendURL to AMBIENT_API_SERVER_URL

[markturansky]

Summary

The BackendURL config field defaulted to http://backend-service.ambient-code.svc:8080/api — a legacy service that no longer exists. Runner pods need BACKEND_API_URL set to call GET /credentials/{id}/token. Since AMBIENT_API_SERVER_URL is already set in all deployments, default BackendURL to it.

Discovered during E2E testing of the credential flow on OSD ambient-s0: runner logs showed DNS failures fetching credentials from the old backend URL.

Test plan

• Runner pod logs show Successfully fetched github credentials from backend instead of DNS failure on backend-service.ambient-code.svc
• Agent can retrieve GitHub token via /credentials/{id}/token and use it

🤖 Generated with Claude Code

Summary by CodeRabbit

• Chores
  • Backend URL configuration now uses environment variable fallback logic (BACKEND_API_URL → AMBIENT_API_SERVER_URL → default to http://localhost:8000), enabling more flexible configuration across different deployment environments.

[coderabbitai]

No actionable comments were generated in the recent review. 🎉

ℹ️ Recent review info

⚙️ Run configuration

Configuration used: Path: .coderabbit.yaml

Review profile: CHILL

Plan: Pro

Run ID: 57b7f5dd-e228-42a9-b9bb-7f5745a96e88

📥 Commits

Reviewing files that changed from the base of the PR and between 7d0dc91 and 1a9e1fa.

📒 Files selected for processing (1)

• components/ambient-control-plane/internal/config/config.go

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📝 Walkthrough

Walkthrough

The control plane backend URL configuration changes from a hardcoded Kubernetes service URL to environment variable-based resolution. It now prioritizes BACKEND_API_URL, falls back to AMBIENT_API_SERVER_URL, and defaults to http://localhost:8000.

Changes

Cohort / File(s)	Summary
Backend URL Configuration components/ambient-control-plane/internal/config/config.go	Modified ControlPlaneConfig.BackendURL resolution logic to use environment variable fallback chain (BACKEND_API_URL → AMBIENT_API_SERVER_URL → http://localhost:8000) instead of hardcoded Kubernetes service URL.

🚥 Pre-merge checks | ✅ 5 | ❌ 1

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Docstring Coverage	⚠️ Warning	Docstring coverage is 0.00% which is insufficient. The required threshold is 80.00%.	Write docstrings for the functions missing them to satisfy the coverage threshold.

✅ Passed checks (5 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	Title follows Conventional Commits format with fix type and control-plane scope; accurately describes the BackendURL configuration change.
Performance And Algorithmic Complexity	✅ Passed	BackendURL initialization replaced with O(1) three-tier fallback pattern using environment variables. Single startup operation with two os.Getenv() calls. No loops, N+1 patterns, or expensive operations introduced.
Security And Secret Handling	✅ Passed	PR modifies BackendURL resolution from hardcoded Kubernetes service URL to environment variable fallback. No secrets hardcoded, no injection vulnerabilities, no sensitive data exposure.
Kubernetes Resource Safety	✅ Passed	PR modifies only Go configuration file; no Kubernetes manifests changed, so custom check targeting K8s resource safety is not applicable.

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✨ Finishing Touches

📝 Generate docstrings

• Create stacked PR
• Commit on current branch

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Commit unit tests in branch fix/cp-credential-rolebinding-and-project-delete

✨ Simplify code

• Create PR with simplified code
• Commit simplified code in branch fix/cp-credential-rolebinding-and-project-delete

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