MastraでAmazon Bedrock / Bedrock Guardrailsを使う方法

import { Agent } from '@mastra/core/agent';
import { Memory } from '@mastra/memory';
import { weatherTool } from '../tools/weather-tool.js';
import { createAmazonBedrock } from '@ai-sdk/amazon-bedrock';
 
const amazonBedrock = createAmazonBedrock({
  region: 'us-east-1',
});
 
export const bedrockTutorialAgent = new Agent({
  id: 'bedrock-tutorial-agent',
  name: 'Bedrock Tutorial Agent',
  instructions: `You are a helpful weather assistant that provides accurate weather information and can help planning activities based on the weather.
 
Your primary function is to help users get weather details for specific locations. When responding:
- Always ask for a location if none is provided
- If the location name isn't in English, please translate it
- If giving a location with multiple parts (e.g. "New York, NY"), use the most relevant part (e.g. "New York")
- Include relevant details like humidity, wind conditions, and precipitation
- Keep responses concise but informative
- If the user asks for activities and provides the weather forecast, suggest activities based on the weather forecast.
- If the user asks for activities, respond in the format they request.
 
Use the weatherTool to fetch current weather data.`,
  model: amazonBedrock('us.anthropic.claude-haiku-4-5-20251001-v1:0'),
  tools: { weatherTool },
  memory: new Memory(),
});

export AWS_BEARER_TOKEN_BEDROCK=your-api-key-here

app.post('/bedrock', async c => {
  const { message } = await c.req.json<{ message?: unknown }>()
 
  if (typeof message !== 'string' || message.trim().length === 0) {
    return c.json({ error: 'message is required' }, 400)
  }
 
  const result = await bedrockTutorialAgent.generate(message)
  return c.text(result.text)
})

$ curl -X POST http://localhost:3000/bedrock -H "Content-Type: application/json" -d '{"message":"I am in Tokyo. What is the weather now?"}'
 
Here's the current weather in Tokyo:
 
**Temperature:** 27.5°C (feels like 32.8°C)
**Conditions:** Partly cloudy
**Humidity:** 78%
**Wind Speed:** 2.6 m/s
**Wind Gust:** 18 m/s
 
It's quite warm and humid in Tokyo right now with moderately strong winds. The "feels like" temperature is noticeably higher due to the humidity, so it may feel more oppressive than the actual temperature suggests. You might want to stay hydrated and consider lighter clothing!

AWSTemplateFormatVersion: '2010-09-09'
Description: Bedrock Guardrail that blocks names in user input or model output.
 
Resources:
  NameBlockGuardrail:
    Type: AWS::Bedrock::Guardrail
    Properties:
      Name: "name-block-guardrail"
      Description: "Checks that text does not include a person's name."
      BlockedInputMessaging: "Your input includes a person's name."
      BlockedOutputsMessaging: "The answer includes a person's name."
      SensitiveInformationPolicyConfig:
        PiiEntitiesConfig:
          - Type: NAME
            Action: BLOCK
            InputAction: BLOCK
            OutputAction: BLOCK
            InputEnabled: true
            OutputEnabled: true
 
Outputs:
  GuardrailId:
    Description: Guardrail ID
    Value: !Ref NameBlockGuardrail

$ aws cloudformation deploy --template-file guardrail.yaml --stack-name guardrail
$ aws cloudformation describe-stacks --stack-name guardrail --query "Stacks[0].Outputs"
[
    {
        "OutputKey": "GuardrailId",
        "OutputValue": "arn:aws:bedrock:us-east-1:123456789012:guardrail/xxxxxxxx",
        "Description": "Guardrail ID"
    }
]

@@ -25,4 +25,16 @@ Use the weatherTool to fetch current weather data.`,
   model: amazonBedrock('us.anthropic.claude-haiku-4-5-20251001-v1:0'),
   tools: { weatherTool },
   memory: new Memory(),
+  defaultOptions: {
+    providerOptions: {
+      bedrock: {
+        guardrailConfig: {
+          guardrailIdentifier: 'xxxxxxxx',
+          guardrailVersion: 'DRAFT',
+          trace: 'enabled',
+          streamProcessingMode: 'async',
+        },
+      },
+    },
+  },
 });

curl -X POST http://localhost:3000/bedrock -H "Content-Type: application/json" -d '{"message":"I am Taro. What is your name?"}'
Your input includes a person's name.

@@ -21,6 +21,13 @@ app.post('/bedrock', async c => {
   }
 
   const result = await bedrockTutorialAgent.generate(message)
+
+  const blocked = result.finishReason === 'content-filter'
+
+  if (blocked) {
+    return c.text(result.text, 400)
+  }
+
   return c.text(result.text)
 })

$ curl -s -X POST http://localhost:3000/bedrock -H "Content-Type: application/json" -d '{"message":"I am Taro. What is your name?"}' -w '\nHTTP_STATUS=%{http_code}\n'
Your input includes a person's name.
HTTP_STATUS=400