UnknownEndpoint：无法访问的主机：“localhost”。尝试使用 express 和 dynamodb local 连接到 localhost

Question

我正在使用 docker compose 创建两个容器，一个用于本地 dynamodb，另一个用于 nodejs express 应用程序。

docker-compose.dev.yml

version: '3'

services:
  dynamodb-local:
    command: "-jar DynamoDBLocal.jar -sharedDb -optimizeDbBeforeStartup -dbPath ./data"
    image: "amazon/dynamodb-local:latest"
    container_name: dynamodb-local
    ports:
      - "8000:8000"
    volumes:
      - "./docker/dynamodb:/home/dynamodblocal/data"
    working_dir: /home/dynamodblocal
    networks:
      - dynamodb-network

  node-app:
    depends_on:
        - dynamodb-local
    container_name: dev-nodejs-backend
    ports:
      - '3000:3000'
    volumes:
      - .:/usr/src/node-app
    environment:
      AWS_ACCESS_KEY_ID: 'DUMMYIDEXAMPLE'
      AWS_SECRET_ACCESS_KEY: 'DUMMYEXAMPLEKEY'
    networks:
      - dynamodb-network
    command: yarn dev -L

networks:
  dynamodb-network:
    driver: bridge

Dockerfile

FROM node:alpine

RUN mkdir -p /usr/src/node-app && chown -R node:node /usr/src/node-app

WORKDIR /usr/src/node-app

COPY package.json yarn.lock ./

USER node

RUN yarn install --pure-lockfile

COPY --chown=node:node . .

EXPOSE 3000

model.js

var AWS = require('aws-sdk');

AWS.config.update({
  accessKeyId: 'YOUR-ACCESSKEYID' ,
  secretAccessKey: 'YOUR-SECRETACCESSKEY' ,
  region: "localhost",
  endpoint: 'http://localhost:8000',
});

const DynamoDB = new AWS.DynamoDB();
var docClient = new AWS.DynamoDB.DocumentClient();

var table = 'URL';

const createTable = async () => {
  var params = {
    TableName : table,
    KeySchema: [
        { AttributeName: "hash", KeyType: "HASH"},  //Partition key
    ],
    AttributeDefinitions: [       
        { AttributeName: "hash", AttributeType: "S" },
    ],
    ProvisionedThroughput: {      
        ReadCapacityUnits: 5, 
        WriteCapacityUnits: 5
    }
};
  const result = await DynamoDB.createTable(params).promise();
  return result;
}

控制台报错

UnknownEndpoint: Inaccessible host: `localhost'. This service may not be available in the `localhost' region.
at Request.ENOTFOUND_ERROR (/usr/src/node-app/node_modules/aws-sdk/lib/event_listeners.js:507:46)
at Request.callListeners (/usr/src/node-app/node_modules/aws-sdk/lib/sequential_executor.js:106:20)
at Request.emit (/usr/src/node-app/node_modules/aws-sdk/lib/sequential_executor.js:78:10)
at Request.emit (/usr/src/node-app/node_modules/aws-sdk/lib/request.js:688:14)
at ClientRequest.error (/usr/src/node-app/node_modules/aws-sdk/lib/event_listeners.js:339:22)
at ClientRequest.<anonymous> (/usr/src/node-app/node_modules/aws-sdk/lib/http/node.js:96:19)
at ClientRequest.emit (node:events:379:20)
at ClientRequest.EventEmitter.emit (node:domain:470:12)
at Socket.socketErrorListener (node:_http_client:462:9)
at Socket.emit (node:events:379:20)
at Socket.EventEmitter.emit (node:domain:470:12)
at emitErrorNT (node:internal/streams/destroy:188:8)
at emitErrorCloseNT (node:internal/streams/destroy:153:3)
at processTicksAndRejections (node:internal/process/task_queues:81:21) {
code: 'UnknownEndpoint',
region: 'localhost',
hostname: 'localhost',
retryable: true,
originalError: Error: connect ECONNREFUSED 127.0.0.1:8000
at TCPConnectWrap.afterConnect [as oncomplete] (node:net:1139:16) {
errno: -111,
code: 'NetworkingError',
syscall: 'connect',
address: '127.0.0.1',
port: 8000,
region: 'localhost',
hostname: 'localhost',
retryable: true,
time: 2021-02-05T14:23:15.559Z
},
time: 2021-02-05T14:23:15.559Z
}

Dynamodb local 在端口 8000 上运行，但我无法从我的 express 应用程序连接它。 我可以在撰写文件中更改什么，或者这是一些不同的错误吗？

Answer 1

在将 s3 与 localstack 一起使用时，我得到了相同的错误输出。检查他们的troubleshooting page 很重要，在我的情况下，它是通过 s3ForcePathStyle 属性解决的

const s3 = new SDK.S3({
  endpoint: "http://localhost:4566",
  s3ForcePathStyle: true,
});

Answer 2

我怀疑你的问题在这里：

AWS.config.update({
  accessKeyId: 'YOUR-ACCESSKEYID' ,
  secretAccessKey: 'YOUR-SECRETACCESSKEY' ,
  region: "localhost",
  endpoint: 'http://localhost:8000',
});

当您尝试从容器内部连接到localhost 时，它会尝试从该容器的角度连接到localhost，即容器本身。

容器认为它是自己独立的机器，因此localhost 指的是容器本身。这不起作用，因为 DynamoDB 没有在您的节点容器内运行。

您希望容器连接到端口 8000 或 docker 主机或 dynamodb-local 容器。由于您使用的是桥接网络，因此后者应该很容易实现 - 将端点设置为http://dynamodb-local:8000/。 Docker 应该为您的容器提供其网络中其他容器名称的 DNS 解析。我建议您查看docs 了解有关桥接网络的更多信息。

tl;dr:这可能会解决问题

AWS.config.update({
  accessKeyId: 'YOUR-ACCESSKEYID' ,
  secretAccessKey: 'YOUR-SECRETACCESSKEY' ,
  region: "localhost",
  endpoint: 'http://dynamodb-local:8000',
});