Amazon Bedrock Mantle

Bedrock Mantle is Amazon Bedrock’s OpenAI-compatible inference endpoint. GoModel calls its Responses API directly, so Responses-only models are not translated to Chat Completions or Bedrock Converse.

This is a separate provider type from Amazon Bedrock Runtime. Use bedrock-mantle for OpenAI-compatible Mantle models and bedrock for Bedrock Runtime Converse models. You can configure both at the same time.

Prerequisites

Enable the models in your AWS account and choose a supported AWS Region. You can authenticate with an Amazon Bedrock API key or the standard AWS credential chain.

Configure

Bedrock API key
AWS credentials (SigV4)

BEDROCK_MANTLE_API_KEY=ABSK...
BEDROCK_MANTLE_BASE_URL=us-east-1
GOMODEL_MASTER_KEY=change-me

BEDROCK_MANTLE_BASE_URL=us-east-1
AWS_ACCESS_KEY_ID=...
AWS_SECRET_ACCESS_KEY=...
# AWS_SESSION_TOKEN=...       # temporary credentials only
GOMODEL_MASTER_KEY=change-me

For SigV4, GoModel uses the AWS SDK credential chain, including AWS_PROFILE, IAM Identity Center, and container or instance roles. In production, prefer workload credentials over long-lived access keys. AWS_BEARER_TOKEN_BEDROCK is also accepted as a bearer-token fallback. Set BEDROCK_MANTLE_BASE_URL with it so provider discovery can enable Mantle. The base URL can be an AWS Region or a complete endpoint. A region is the recommended form:

BEDROCK_MANTLE_BASE_URL=us-west-2
# Equivalent host: https://bedrock-mantle.us-west-2.api.aws

For an API-key or YAML configuration where the base URL is omitted, GoModel uses BEDROCK_MANTLE_REGION, then AWS_REGION, then AWS_DEFAULT_REGION, and finally us-east-1. With only IAM credentials, set BEDROCK_MANTLE_BASE_URL so provider discovery enables Mantle. Or configure the provider in config.yaml:

providers:
  bedrock-mantle:
    type: bedrock-mantle
    base_url: us-east-1
    api_key: "${BEDROCK_MANTLE_API_KEY}"

Call GPT-5.6

curl -s http://localhost:8080/v1/responses \
  -H "Authorization: Bearer $GOMODEL_MASTER_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "model": "openai.gpt-5.6-sol",
    "input": "Explain why idempotency matters in distributed systems."
  }'

Streaming uses the same gateway endpoint with "stream": true. previous_response_id, tools, reasoning controls, and unknown extension fields are forwarded to Mantle without translating the request to chat.

GPT-5.6 availability

Model	Model ID	Context	AWS Regions
Sol	`openai.gpt-5.6-sol`	272K	`us-east-1`, `us-east-2`
Terra	`openai.gpt-5.6-terra`	272K	`us-east-1`, `us-east-2`, `us-west-2`
Luna	`openai.gpt-5.6-luna`	272K	`us-east-1`, `us-east-2`, `us-west-2`

These models support the Responses API, not Chat Completions, Converse, or Invoke. GoModel automatically sends them to /openai/v1/responses, the model- specific path required by AWS. Other Mantle models use /v1/responses or /v1/chat/completions as appropriate.

Endpoint path selection

BEDROCK_MANTLE_API_MODE controls which OpenAI-compatible path GoModel uses:

Value	Behavior
`auto`	Default. Uses `/openai/v1` for known model families that require it and `/v1` for other models.
`openai`	Forces `/openai/v1` for inference requests.
`standard`	Forces `/v1` for inference requests.

The model catalog always uses /v1/models. Use an override when AWS adds a model before GoModel’s automatic path list is updated. In YAML, set the same option with api_mode:

providers:
  mantle-preview:
    type: bedrock-mantle
    base_url: us-east-1
    api_mode: openai
    models:
      - openai.gpt-5.6-sol

Multiple Mantle providers

Use suffixed environment variables for separate regions or accounts:

BEDROCK_MANTLE_EAST_API_KEY=ABSK...
BEDROCK_MANTLE_EAST_BASE_URL=us-east-1

BEDROCK_MANTLE_WEST_API_KEY=ABSK...
BEDROCK_MANTLE_WEST_BASE_URL=us-west-2

This registers bedrock-mantle-east and bedrock-mantle-west.

Troubleshooting

GPT-5.6 returns 404 or rejects the request — use the bedrock-mantle provider type. The Bedrock Runtime provider uses Converse, which GPT-5.6 does not support.
403 / access denied — enable model access and verify that the API key or IAM principal can invoke Bedrock Mantle inference in that Region.
Provider is not discovered with AWS_BEARER_TOKEN_BEDROCK or an IAM role — set BEDROCK_MANTLE_BASE_URL to enable the keyless provider.
A newly released model uses the wrong route — set BEDROCK_MANTLE_API_MODE=openai or standard for that provider instance.

Cloud Platforms

Amazon Bedrock Mantle

Prerequisites

Configure

Call GPT-5.6

GPT-5.6 availability

Endpoint path selection

Multiple Mantle providers

Troubleshooting

References

​Prerequisites

​Configure

​Call GPT-5.6

​GPT-5.6 availability

​Endpoint path selection

​Multiple Mantle providers

​Troubleshooting

​References

Prerequisites

Configure

Call GPT-5.6

GPT-5.6 availability

Endpoint path selection

Multiple Mantle providers

Troubleshooting

References