无法从应用程序容器到达postgres容器

Question

我有一个docker-composer.yml，它正在设置两个服务:server和db。作为server服务的node.js服务器使用pg连接到PostgreSQL数据库；而db服务是一个PostgreSQL映像。

在服务器启动时，它尝试连接到数据库，但获得超时。

version: '3.8'

services:
  server:
    image: myapi
    build: .
    container_name: server
    env_file: .env
    environment:
      - PORT=80
      - DATABASE_URL=postgres://postgres:postgres@db:15432/mydb
      - REDIS_URL=redis://redis
    ports:
      - 3000:80
    depends_on:
      - db
    command: node script.js
    restart: unless-stopped

  db:
    image: postgres
    container_name: db
    environment:
      POSTGRES_USER: postgres
      POSTGRES_PASSWORD: postgres
      POSTGRES_DB: mydb
    ports:
      - 15432:15432
    volumes:
      - db-data:/var/lib/postgresql/data
    command: -p 15432
    restart: unless-stopped

volumes:
  db-data:

DB服务输出：

db        | 
db        | PostgreSQL Database directory appears to contain a database; Skipping initialization
db        | 
db        | 2020-11-05 20:18:15.865 UTC [1] LOG:  starting PostgreSQL 13.0 (Debian 13.0-1.pgdg100+1) on x86_64-pc-linux-gnu, compiled by gcc (Debian 8.3.0-6) 8.3.0, 64-bit
db        | 2020-11-05 20:18:15.865 UTC [1] LOG:  listening on IPv4 address "0.0.0.0", port 15432
db        | 2020-11-05 20:18:15.865 UTC [1] LOG:  listening on IPv6 address "::", port 15432
db        | 2020-11-05 20:18:15.873 UTC [1] LOG:  listening on Unix socket "/var/run/postgresql/.s.PGSQL.15432"
db        | 2020-11-05 20:18:15.880 UTC [25] LOG:  database system was shut down at 2020-11-05 20:18:12 UTC
db        | 2020-11-05 20:18:15.884 UTC [1] LOG:  database system is ready to accept connections

script.js-由server服务中的命令使用。

const pg = require('pg');

console.log(process.env.DATABASE_URL);

const pool = new pg.Pool({
  connectionString: process.env.DATABASE_URL,
  connectionTimeoutMillis: 5000,
});
pool.connect((err, _, done) => {
  if (err) {
    console.error(err);
    done(err);
  }
  done();
});
pool.query('SELECT NOW()', (err, res) => {
  console.log(err, res);
  pool.end();
});

const client = new pg.Client({
  connectionString: process.env.DATABASE_URL,
  connectionTimeoutMillis: 5000,
});
client.connect(console.error);
client.query('SELECT NOW()', (err, res) => {
  console.log(err, res);
  client.end();
});

服务器服务输出：

server    | postgres://postgres:postgres@db:15432/mydb
server    | Error: Connection terminated due to connection timeout
server    |     at Connection.<anonymous> (/home/node/app/node_modules/pg/lib/client.js:255:9)
server    |     at Object.onceWrapper (events.js:421:28)
server    |     at Connection.emit (events.js:315:20)
server    |     at Socket.<anonymous> (/home/node/app/node_modules/pg/lib/connection.js:78:10)
server    |     at Socket.emit (events.js:315:20)
server    |     at emitCloseNT (net.js:1659:8)
server    |     at processTicksAndRejections (internal/process/task_queues.js:79:21)
server    |     at runNextTicks (internal/process/task_queues.js:62:3)
server    |     at listOnTimeout (internal/timers.js:523:9)
server    |     at processTimers (internal/timers.js:497:7)
server    | Error: Connection terminated due to connection timeout
server    |     at Connection.<anonymous> (/home/node/app/node_modules/pg/lib/client.js:255:9)
server    |     at Object.onceWrapper (events.js:421:28)
server    |     at Connection.emit (events.js:315:20)
server    |     at Socket.<anonymous> (/home/node/app/node_modules/pg/lib/connection.js:78:10)
server    |     at Socket.emit (events.js:315:20)
server    |     at emitCloseNT (net.js:1659:8)
server    |     at processTicksAndRejections (internal/process/task_queues.js:79:21)
server    |     at runNextTicks (internal/process/task_queues.js:62:3)
server    |     at listOnTimeout (internal/timers.js:523:9)
server    |     at processTimers (internal/timers.js:497:7) undefined
server    | Error: timeout expired
server    |     at Timeout._onTimeout (/home/node/app/node_modules/pg/lib/client.js:95:26)
server    |     at listOnTimeout (internal/timers.js:554:17)
server    |     at processTimers (internal/timers.js:497:7)
server    | Error: Connection terminated unexpectedly
server    |     at Connection.<anonymous> (/home/node/app/node_modules/pg/lib/client.js:255:9)
server    |     at Object.onceWrapper (events.js:421:28)
server    |     at Connection.emit (events.js:315:20)
server    |     at Socket.<anonymous> (/home/node/app/node_modules/pg/lib/connection.js:78:10)
server    |     at Socket.emit (events.js:315:20)
server    |     at emitCloseNT (net.js:1659:8)
server    |     at processTicksAndRejections (internal/process/task_queues.js:79:21) undefined
server    | postgres://postgres:postgres@db:15432/mydb
...

从主机运行的脚本的输出：

➜  node script.js
postgres://postgres:postgres@localhost:15432/mydb
null Client { ... }
undefined Result { ... }
null Result { ... }

此输出表示连接成功。

我无法从server容器到达db容器，因为连接超时，但我可以从主机计算机到达db容器，因为连接成功。

初始化顺序：

我使用depends_on来确保db容器首先启动，但我知道这并不能确保数据库首先初始化，然后才是服务器。这不是问题，因为当超时发生时，服务器会中断，它会再次运行，因为它是用restart:unless-stopped设置的。因此，如果数据库在第一次或第二次尝试启动服务器时仍在初始化，则没有问题，因为服务器将继续重新启动，直到连接成功（从未发生过）

更新：

docker exec -it server psql postgres://postgres:postgres@db:15432/mydb

Answer 1

感谢您提供的来源，以转载该问题。docker-compose文件中没有您已经排除的问题。

问题出在DockerFile和您正在使用的node-pg版本之间。

您正在使用node:14-alpine和pg:7.18.2。结果发现Node14和node-pg的早期版本上存在一个bug。

我已经在你提供的分支上验证了这两个解决方案，它们都起作用了。