DSQLの最大接続時間超過エラーが発生しないLambdaの実装について検証してみた

import { Client } from "pg";
import { DsqlSigner } from "@aws-sdk/dsql-signer";

const region = process.env.AWS_REGION;
const clusterEndpoint = `${process.env.DSQL_CLUSTER_IDENTIFIER}.dsql.${region}.on.aws`;
const signer = new DsqlSigner({
	hostname: clusterEndpoint,
	region,
});
const token = await signer.getDbConnectAdminAuthToken();
const client = new Client({
	host: clusterEndpoint,
	port: 5432,
	database: "postgres",
	user: "admin",
	password: token,
	ssl: true,
});
await client.connect();
client.password;

export const handler = async (event, context) => {
	await client.query("SELECT now()");
};

2025-08-16T05:08:03.735Z	668be42f-8fb4-40b9-b922-917b4961fd6a	ERROR	Uncaught Exception 	
{
    "errorType": "Error",
    "errorMessage": "Connection terminated unexpectedly",
    "stack": [
        "Error: Connection terminated unexpectedly",
        "    at Connection.<anonymous> (/var/task/node_modules/pg/lib/client.js:136:73)",
        "    at Object.onceWrapper (node:events:632:28)",
        "    at Connection.emit (node:events:518:28)",
        "    at Socket.<anonymous> (/var/task/node_modules/pg/lib/connection.js:62:12)",
        "    at Socket.emit (node:events:530:35)",
        "    at TCP.<anonymous> (node:net:351:12)",
        "    at TCP.callbackTrampoline (node:internal/async_hooks:130:17)"
    ]
}
[ERROR] [1755320883795] LAMBDA_RUNTIME Failed to post handler success response. Http response code: 400.
END RequestId: 3ae7d2b9-386f-4cf5-8be4-8a07c441bb17
REPORT RequestId: 3ae7d2b9-386f-4cf5-8be4-8a07c441bb17	Duration: 424.60 ms	Billed Duration: 425 ms	Memory Size: 128 MB	Max Memory Used: 109 MB	Status: error	Error Type: Runtime.ExitError
XRAY TraceId: 1-68a01233-79a00cff59419f8a19543d5a	SegmentId: 19f811623978708f	Sampled: true

AWS Application Signals enabled.
AWS Application Signals metrics export interval capped to 60000
Enabled batch unsampled span processor for Lambda environment.
OTEL_LOGS_EXPORTER is empty. Using default otlp exporter.
OTEL_METRICS_EXPORTER contains "none". Metric provider will not be initialized.
Setting TraceProvider for instrumentations at the end of initialization
AWS Distro of OpenTelemetry automatic instrumentation started successfully
(node:2) [DEP0040] DeprecationWarning: The `punycode` module is deprecated. Please use a userland alternative instead.
(Use `node --trace-deprecation ...` to show where the warning was created)
START RequestId: 3ae7d2b9-386f-4cf5-8be4-8a07c441bb17 Version: $LATEST
END RequestId: 3ae7d2b9-386f-4cf5-8be4-8a07c441bb17
REPORT RequestId: 3ae7d2b9-386f-4cf5-8be4-8a07c441bb17 Duration: 1115.67 ms Billed Duration: 1116 ms Memory Size: 128 MB Max Memory Used: 112 MB XRAY TraceId: 1-68a01233-79a00cff59419f8a19543d5a SegmentId: 4f516b95af47814f Sampled: true

import { Pool } from "pg";
import { DsqlSigner } from "@aws-sdk/dsql-signer";

const region = process.env.AWS_REGION;
const clusterEndpoint = `${process.env.DSQL_CLUSTER_IDENTIFIER}.dsql.${region}.on.aws`;
const getToken = async () => {
    const signer = new DsqlSigner({
        hostname: clusterEndpoint,
        region,
    });
    return signer.getDbConnectAdminAuthToken()
}

const pool = new Pool({
	host: clusterEndpoint,
	port: 5432,
	database: "postgres",
	user: "admin",
	password: getToken,
	ssl: true,
	maxLifetimeSeconds: 60 * 50,
	idleTimeoutMillis: 1000 * 60 * 50
});

export const handler = async (event, context) => {
	await pool.query("SELECT now()");
};

filter ispresent(attributes.db.name)
| display @timestamp, name
| sort startTimeUnixNano

AWSTemplateFormatVersion: 2010-09-09
Transform:
- AWS::Serverless-2016-10-31
Globals:
  Function:
    Timeout: 10
    Tracing: Active
    Runtime: nodejs22.x
    Layers:
      - arn:aws:lambda:us-east-1:615299751070:layer:AWSOpenTelemetryDistroJs:8
    Environment:
      Variables:
        OTEL_NODE_ENABLED_INSTRUMENTATIONS: pg
        AWS_LAMBDA_EXEC_WRAPPER: /opt/otel-instrument
        DSQL_CLUSTER_IDENTIFIER: !Ref Dsql
Resources:  
  Dsql:
    Type: AWS::DSQL::Cluster
    Properties:
      DeletionProtectionEnabled: false
  DsqlWithPgClient:
    Type: AWS::Serverless::Function
    Properties:      
      Handler: src/dsql-with-pg-client.handler
      Role: !GetAtt LambdaRole.Arn
      Events:
        CloudWatchEvent:
          Type: Schedule
          Properties:
            Schedule: rate(5 minutes)
  DsqlWithPgPool:
    Type: AWS::Serverless::Function
    Properties:      
      Handler: src/dsql-with-pg-pool.handler
      Role: !GetAtt LambdaRole.Arn
      Events:
        CloudWatchEvent:
          Type: Schedule
          Properties:
            Schedule: rate(5 minutes)
  LambdaRole:
      Type: AWS::IAM::Role
      Properties:
        AssumeRolePolicyDocument:
          Version: '2012-10-17'
          Statement:
          - Effect: Allow
            Principal:
              Service:
              - 'lambda.amazonaws.com'
            Action: sts:AssumeRole
        Policies:
        -
          PolicyName: dsql-blog-policy
          PolicyDocument:
            Version: "2012-10-17"
            Statement:
            -
              Effect: "Allow"
              Action:
                - 'dsql:*'
                - "logs:*"
                - "xray:*"
              Resource: '*'