为什么我的文档化LoopBack4应用程序无法成功运行，并收到消息"ConnectionError:查找实例失败“？

Question

我创建了一个LoopBack 4应用程序来实现LoopBack 4教程中用户数据模型上的CRUD操作，该应用程序在VSCode和Dockerization (Linux模式)中运行良好。之后，我添加了基于用户名和密码的基本身份验证功能。该应用程序在我的VSCode中再次运行良好，但由于"ConnectionError:未能查找实例“错误而失败地运行。

我的码头引擎: 19.03.8

我的操作系统: Windows 10 Pro

我的LB4应用程序：https://github.com/frank-nguyen-vd/LB4-Tutorial

来自码头的错误日志：

​

Mon, 29 Jun 2020 01:39:59 GMT tedious deprecated The default value for `config.options.enableArithAbort` will change from `false` to `true` in the next major version of `tedious`. Set the value to `true` or `false` explicitly to silence this message. at node_modules/mssql/lib/tedious/connection-pool.js:61:23
Server is running at http://127.0.0.1:3000

Try http://127.0.0.1:3000/ping

Connection fails: ConnectionError: Failed to lookup instance on HOPE-L-191 - getaddrinfo ENOTFOUND HOPE-L-191

It will be retried for the next request.

events.js:174

throw er; // Unhandled 'error' event

^


ConnectionError: Failed to lookup instance on HOPE-L-191 - getaddrinfo ENOTFOUND HOPE-L-191

at Connection.tedious.once.err (/home/node/app/node_modules/mssql/lib/tedious/connection-pool.js:68:17)

at Object.onceWrapper (events.js:286:20)

at Connection.emit (events.js:198:13)

at _instanceLookup.InstanceLookup.instanceLookup (/home/node/app/node_modules/tedious/lib/connection.js:1100:16)

at sender.execute (/home/node/app/node_modules/tedious/lib/instance-lookup.js:69:13)

at GetAddrInfoReqWrap.invokeLookupAll [as callback] (/home/node/app/node_modules/tedious/lib/sender.js:155:16)

at GetAddrInfoReqWrap.onlookupall [as oncomplete] (dns.js:68:17)

Emitted 'error' event at:

at UserDsDataSource.postInit (/home/node/app/node_modules/loopback-datasource-juggler/lib/datasource.js:502:16)

at /home/node/app/node_modules/loopback-connector-mssql/lib/mssql.js:36:19

at Immediate.<anonymous> (/home/node/app/node_modules/loopback-connector-mssql/lib/mssql.js:89:14)

at runCallback (timers.js:706:11)

at tryOnImmediate (timers.js:676:5)

at processImmediate (timers.js:658:5)

​

我的Dockerfile：

FROM node:10-slim
USER node
RUN mkdir -p /home/node/app
WORKDIR /home/node/app
COPY --chown=node package*.json ./
COPY --chown=node . .
RUN npm run build
ENV HOST=0.0.0.0 PORT=3000
EXPOSE ${PORT}
CMD [ "node", "." ]

我的package.json

​

{
  "name": "mockup",
  "version": "1.0.0",
  "description": "mockup",
  "keywords": [
    "loopback-application",
    "loopback"
  ],
  "main": "dist/index.js",
  "types": "dist/index.d.ts",
  "engines": {
    "node": ">=10.16"
  },
  "scripts": {
    "build": "lb-tsc",
    "build:watch": "lb-tsc --watch",
    "lint": "npm run prettier:check && npm run eslint",
    "lint:fix": "npm run eslint:fix && npm run prettier:fix",
    "prettier:cli": "lb-prettier \"**/*.ts\" \"**/*.js\"",
    "prettier:check": "npm run prettier:cli -- -l",
    "prettier:fix": "npm run prettier:cli -- --write",
    "eslint": "lb-eslint --report-unused-disable-directives .",
    "eslint:fix": "npm run eslint -- --fix",
    "pretest": "npm run clean && npm run build",
    "test": "lb-mocha --allow-console-logs \"dist/__tests__\"",
    "posttest": "npm run lint",
    "test:dev": "lb-mocha --allow-console-logs dist/__tests__/**/*.js && npm run posttest",
    "docker:build": "docker build -t pcms-mockup .",
    "docker:run": "docker run -p 3000:3000 -d pcms-mockup",
    "migrate": "node ./dist/migrate",
    "openapi-spec": "node ./dist/openapi-spec",
    "prestart": "npm run build",
    "start": "node -r source-map-support/register .",
    "clean": "lb-clean dist *.tsbuildinfo .eslintcache"
  },
  "repository": {
    "type": "git"
  },
  "author": "",
  "license": "",
  "files": [
    "README.md",
    "dist",
    "src",
    "!*/__tests__"
  ],
  "dependencies": {
    "@loopback/authentication": "^4.2.8",
    "@loopback/authentication-jwt": "^0.4.2",
    "@loopback/authentication-passport": "^2.1.8",
    "@loopback/boot": "^2.3.4",
    "@loopback/core": "^2.9.0",
    "@loopback/openapi-v3": "^3.4.4",
    "@loopback/repository": "^2.8.0",
    "@loopback/rest": "^5.1.2",
    "@loopback/rest-explorer": "^2.2.5",
    "@loopback/service-proxy": "^2.3.3",
    "passport-http": "^0.3.0",
    "tslib": "^2.0.0"
  },
  "devDependencies": {
    "@loopback/build": "^6.0.0",
    "@loopback/eslint-config": "^8.0.2",
    "@loopback/testlab": "^3.1.8",
    "@types/node": "^10.17.26",
    "@types/passport-http": "^0.3.8",
    "eslint": "^7.3.1",
    "source-map-support": "^0.5.19",
    "typescript": "~3.9.5"
  }
}

​

在错误日志中，它提到了我不使用的环回连接器-mssql。我试着安装环回连接器-mssql(并保存到package.json)并再次构建映像，但是错误并没有消失。

您能帮我指出造成此错误的原因吗？

--加上6月30日-20日

我附加了我唯一的.datasource文件，它不包括mssql。

​

import {inject, lifeCycleObserver, LifeCycleObserver} from '@loopback/core';
import {juggler} from '@loopback/repository';

const config = {
  name: 'db',
  connector: 'memory',
  localStorage: 'y',
  file: 'data/db.json',
};

// Observe application's life cycle to disconnect the datasource when
// application is stopped. This allows the application to be shut down
// gracefully. The `stop()` method is inherited from `juggler.DataSource`.
// Learn more at https://loopback.io/doc/en/lb4/Life-cycle.html
@lifeCycleObserver('datasource')
export class DbDataSource extends juggler.DataSource
  implements LifeCycleObserver {
  static dataSourceName = 'db';
  static readonly defaultConfig = config;

  constructor(
    @inject('datasources.config.db', {optional: true})
    dsConfig: object = config,
  ) {
    super(dsConfig);
  }
}

​

Answer 1

当我将LB4应用程序文件夹(没有文件夹node_modules)复制到另一个位置并运行"npm && npm“时，我的错误与Docker报告的错误相同。这意味着我的问题是因为缺少我的代码所需的包“环回连接器-mssql”。我无法在代码中找到需要mssql的地方。我只在LoopBack 4教程的基础上添加身份验证。无论如何，在我安装了丢失的软件包后，它就可以工作了。

但是，我仍然不知道在我的代码中哪里需要mssql连接器>.<。