feat: Call Bedrock model from backend lambda

backend/backend_stack.py

@@ -1,4 +1,4 @@
-from aws_cdk import Stack, aws_lambda, aws_apigateway
+from aws_cdk import Stack, aws_lambda, aws_apigateway, aws_iam
 from constructs import Construct
 
 
@@ -14,6 +14,14 @@ def __init__(self, scope: Construct, id: str, **kwargs):
             code=aws_lambda.Code.from_asset("backend/lambda"),
         )
 
+        backend_lambda.add_to_role_policy(
+            aws_iam.PolicyStatement(
+                actions=["bedrock:InvokeModel"],
+                resources=["*"],
+                effect=aws_iam.Effect.ALLOW,
+            )
+        )
+
         backend_apigw = aws_apigateway.LambdaRestApi(
             scope=self,
             id="ChatbotBackendAPI",
@@ -22,5 +30,4 @@ def __init__(self, scope: Construct, id: str, **kwargs):
 
         chatbot_res = backend_apigw.root.add_resource("chatbot")
 
-        chatbot_res.add_method("GET")
         chatbot_res.add_method("POST")

backend/lambda/backend_lambda.py

@@ -1,12 +1,23 @@
 import json
 
+import boto3
+
 
 def handler(event, context):
-    print('request: {}'.format(json.dumps(event)))
+    body = event['body']
+    print('request: {}'.format(json.dumps(body)))
+
+    bedrock = boto3.client('bedrock-runtime')
+    response = bedrock.invoke_model(
+        modelId='amazon.titan-text-lite-v1',
+        contentType='application/json',
+        body=body
+    )
+
     return {
         'statusCode': 200,
         'headers': {
-            'Content-Type': 'text/plain'
+            'Content-Type': response['contentType']
         },
-        'body': 'Hello, CDK! You have hit {}\n'.format(event['path'])
+        'body': json.loads(response['body'])
     }

pyproject.toml

@@ -9,6 +9,7 @@ readme = "README.md"
 python = "^3.11"
 aws-cdk-lib = "^2.116.1"
 constructs = "^10.3.0"
+boto3 = "^1.34.9"
 
 
 [tool.poetry.group.dev.dependencies]