fix(bedrock): forward litellm_params AWS auth to batch create signing

[noahnistler]

TLDR

Problem this solves:

• Cross-account Bedrock batch jobs fail with "Cross-account pass role is not allowed"
• Deployment-level AWS auth (litellm_params) was dropped before signing the request

How it solves it:

• Merge litellm_params into the params used for region lookup and SigV4 signing
• The cross-account role configured on the deployment now signs the request

User Flow

Before: an admin who configured a Bedrock deployment with a cross-account batch role gets every batch job rejected by AWS

1. They POST to http://litellm-domain/v1/files with purpose=batch, staging an input file against a Bedrock deployment whose config sets a cross-account IAM role
2. They POST to http://litellm-domain/v1/batches with that file id, endpoint /v1/chat/completions, and completion_window 24h
3. The response body carries an AWS error saying the cross-account pass role is not allowed, even though the deployment's role ARN is correct

After: the same batch job is accepted

1. The admin sends the same POST http://litellm-domain/v1/files
2. They send the same POST http://litellm-domain/v1/batches
3. The response now returns a batch object with a job id and a validating/in-progress status instead of an error

Relevant issues

Linear ticket

Resolves LIT-4223

Pre-Submission checklist

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• I have added meaningful tests
• My PR passes all CI/CD checks (e.g., lint, format, unit tests)
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Delays in PR merge?

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Screenshots / Proof of Fix

Reproducing this needs a Bedrock deployment with a real cross-account IAM role (aws_role_name for the assume-role hop, aws_batch_role_arn for the job's roleArn), which I don't have credentials for. Steps below reproduce it against a live proxy for anyone who does.

Config (dev_config.yaml), pointed at a Bedrock model whose account differs from the calling identity's account:

model_list:
  - model_name: bedrock-cross-account-batch
    litellm_params:
      model: bedrock/anthropic.claude-3-haiku-20240307-v1:0
      aws_region_name: us-east-1
      aws_role_name: arn:aws:iam::<TARGET_ACCOUNT_ID>:role/<cross-account-assume-role>
      aws_batch_role_arn: arn:aws:iam::<TARGET_ACCOUNT_ID>:role/<bedrock-batch-execution-role>
      s3_bucket_name: <your-bucket>

Start the proxy against that config, then:

FILE_ID=$(curl -s -X POST http://localhost:4000/v1/files \
  -H "Authorization: Bearer sk-1234" \
  -F purpose="batch" \
  -F file="@input.jsonl" | jq -r .id)

curl -s -X POST http://localhost:4000/v1/batches \
  -H "Authorization: Bearer sk-1234" \
  -H "Content-Type: application/json" \
  -d "{\"input_file_id\": \"$FILE_ID\", \"endpoint\": \"/v1/chat/completions\", \"completion_window\": \"24h\", \"model\": \"bedrock-cross-account-batch\"}"

Before the fix (checked out at 9de3315dad, the commit this branch is based on): the batches call fails, and the proxy log shows the AWS error body containing "Cross-account pass role is not allowed."

After the fix (this branch, 6b50fcc8a5): the same call returns a batch object with an id and a validating/in-progress status.

Type

🐛 Bug Fix

Caveats (if any)

• The equivalent file-upload signing path (files/transformation.py) has a similar-looking gap; left untouched to keep this PR scoped to batch creation

Final Attestation

• The tests check the right things, including the edge cases, and regressions in the respective real-world customer use-cases are not possible after this PR

[greptile-apps]

Greptile Summary

This PR forwards deployment-level AWS authentication and region parameters into Bedrock batch request signing so configured cross-account credentials are retained.

• Merges batch optional parameters with deployment parameters before region resolution and SigV4 signing.
• Adds a regression test covering deployment-provided role and region forwarding.

Confidence Score: 5/5

The PR appears safe to merge, with the Bedrock batch request now using the deployment’s configured AWS authentication and region consistently.

The active batch caller supplies deployment parameters through litellm_params and an empty optional_params mapping; the merged mapping therefore restores the required signer inputs, while the pre-signed HTTP branch sends the same URL used during signing.

Important Files Changed

Filename	Overview
litellm/llms/bedrock/batches/transformation.py	Correctly supplies deployment AWS settings to both endpoint construction and the existing Bedrock signer without changing the HTTP transport path.
tests/test_litellm/llms/bedrock/batches/test_transformation.py	Adds focused mocked coverage confirming that the configured assume-role ARN and region reach request signing.

_{Reviews (1): Last reviewed commit: "fix(bedrock): forward litellm_params AWS..." | Re-trigger Greptile}

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.

📢 Thoughts on this report? Let us know!

[codspeed-hq]

Merging this PR will not alter performance

✅ 31 untouched benchmarks

---

_{Comparing Evernorth:litellm_bedrock_batch_cross_account_role (6b50fcc) with litellm_internal_staging (9de3315)}

[mateo-berri]

Thanks Noah, the diagnosis was right. PR #36160 merged this same litellm_params merge for batch and file signing, so closing this as superseded.

[shivamrawat1]

@linear attach this pr BerriAI/litellm#36160to the ticket

[linear-code]

Attached this pull request to LIT-5303.