fix: use osls 4 SDK v3 config for AWS credentials

[jimmyn]

osls 4 removed provider.getCredentials() (it throws AWS_SDK_V2_SURFACE_REMOVED). resolveCredentials catches that and falls back to fromNodeProviderChain(), which ignores provider.profile and --aws-profile.

• Use the credentials from provider.getAwsSdkV3Config() when it exists.
• Keep getCredentials() for Serverless 3 / osls 3.
• Add tests for both paths.

Summary by CodeRabbit

• Bug Fixes
  • Improved AWS credential resolution for Serverless Framework v4, supporting both static credentials and credentials provided asynchronously.
  • When v4 credentials are unavailable, the app now falls back to the standard AWS credential provider chain.
  • Existing credential resolution for Serverless Framework v3 and earlier remains supported.

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📝 Walkthrough

Walkthrough

Credential resolution now supports credentials from Serverless v4’s getAwsSdkV3Config() API. Providers without that method continue to use the existing getCredentials() path.

Changes

Provider credential resolution

Layer / File(s)	Summary
Credential API and resolution src/types/serverless.d.ts, src/index.ts, src/__tests__/credentials.test.ts	Provider declares the optional getAwsSdkV3Config() API. The resolver uses its credentials, invokes a credential provider when supplied, and uses the default Node provider chain when credentials are absent. Tests cover async and static v4 credentials and the Serverless 3 / osls 3 path.

Priority: ➖ Normal

Estimated code review effort: 2 (Simple) | ~10 minutes

Change: Bug fix

Sequence Diagram(s)

sequenceDiagram
  participant Provider
  participant resolveCredentials
  participant DefaultNodeProviderChain
  resolveCredentials->>Provider: getAwsSdkV3Config()
  Provider-->>resolveCredentials: configuration with optional credentials
  alt configuration includes credentials
    resolveCredentials->>resolveCredentials: invoke credentials if they are a provider
  else configuration has no credentials
    resolveCredentials->>DefaultNodeProviderChain: request credentials
    DefaultNodeProviderChain-->>resolveCredentials: resolved credentials
  end
  alt getAwsSdkV3Config is unavailable
    resolveCredentials->>Provider: getCredentials()
    Provider-->>resolveCredentials: credentials
  end

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Merge Risk: 🟡 Moderate · up to 28c76

Credentials may resolve successfully while AWS calls fail in deployments requiring an osls-configured proxy or custom CA. Pass the v4 client configuration through before merging, unless that limitation is explicitly accepted.

Security Architecture Review

Security architecture risk: 🔵 Low · up to 28c76

The new path uses credentials supplied by Serverless v4 and retains the older path for Serverless v3. No new credential-boundary bypass was identified, but the change affects several AWS clients and some external behavior remains unverified.

Retained concerns
No architecture-level concerns identified.

Security review details

Security Blast Radius

• observed — A credential identity selected by this resolver can authorize calls through five AWS client types. ACM uses a different region but the same credential provider.

Trust Boundaries and Controls

• inferred — The changed path preserves the provider-to-client credential boundary when v4 supplies credentials. The default-chain path for missing credentials also exists in the older resolver; available evidence does not establish a newly reachable identity bypass.

Hardening Proposals

• proposed — Document and exercise the intended v4 behavior when configuration has no credentials or rejects, particularly where the host’s default credential chain could represent a different AWS identity. This is a precaution, not an established PR-introduced bypass.

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title clearly and concisely describes the main change: using the osls 4 SDK v3 configuration for AWS credentials while remaining consistent with the implementation and objectives.
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check. Docstring coverage is scoped to functions touched by this diff. Analyzed 0 functions across 3…
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.

✨ Finishing Touches

🧪 Generate unit tests (beta)

• Create a new PR

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Actionable comments posted: 1

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🤖 Prompt to fix review comments

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Inline comments:
Review comments at @src/index.ts:
- Line 76: Preserve the full configuration returned by
provider.getAwsSdkV3Config() in the client setup instead of extracting only
credentials. Update the AWS client construction to pass that configuration
through, while retaining the existing ACM region override.

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ℹ️ Review info

⚙️ Run configuration

Configuration used: defaults

Review profile: CHILL

Plan: Advanced

Run ID: e968ddee-4020-4f38-9e92-eb635b27ebab

📥 Commits

Reviewing files that changed from the base of the PR and between 1861f86 and 28c762c.

📒 Files selected for processing (3)

• src/__tests__/credentials.test.ts
• src/index.ts
• src/types/serverless.d.ts

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