Server in docker container unable to connect to postgres database in another docker container

问题

I have a node server that's trying to connect to a postgres database using knex. Both are in docker containers with the same custom network. I keep getting ECONNREFUSED errors. I've poked around in the database container and I see that my DB (test_db) has been created by psql but it has no permissions. After giving root permissions, I'm still getting the same issues. I've tried removing the volumes with docker-compose down -v but still no luck. I've also tried removing knex and just using node-postgres but same errors. I'm also unable to connect to the Db from the host using pgadmin. Would appreciate any help!

Here's my docker-compose.yml

version: "3"

services:
  server:
    build:
      context: .
      dockerfile: development.Dockerfile
    ports:
      - "8081:8081"
    volumes:
      - .:/src
      - /src/node_modules
    networks:
      - dev-network
    environment:
      DB_HOSTNAME: pg-development
      DB_USER: root
      DB_PASSWORD: helloworld
      DB_PORT: 3306
      DB_NAME: test_dev
    depends_on:
      - pg-development
  pg-development:
    image: postgres
    environment:
      POSTGRES_USER: root
      POSTGRES_PASSWORD: helloworld
      POSTGRES_DB: test_dev
    ports:
      - "3308:3306"
    volumes:
      - dbdata:/data/db
    networks:
      - dev-network
    healthcheck:
      test: ["CMD-SHELL", "pg_isready -U root -d test_dev"]
      interval: 10s
      timeout: 2s
      retries: 10
networks:
  dev-network:
    driver: bridge

volumes:
  dbdata:

Here's my db connection

import knex from "knex";

const connection = {
  host: process.env.DB_HOSTNAME,
  user: process.env.DB_USER,
  password: process.env.DB_PASSWORD,
  port: Number(process.env.DB_PORT),
  database: process.env.DB_USER,
};

const db = knex({
  client: "pg",
  connection,
  debug: true,
  pool: {
    min: 0,
    max: 50,
    afterCreate: function (conn, done) {
      conn.query('SET timezone="UTC";', function (err) {
        if (err) {
          done(err, conn);
        }
      });
    },
  },
});

回答1:

I'ts because you are exposing the wrong port in the pg-development container:

https://docs.docker.com/compose/reference/port/

port [options] SERVICE PRIVATE_PORT

The port you are exposing in the database is the port 3308, the correct configuration sould be:

...
ports:
      - "3306:3306"
...

回答2:

The reason this wasn't working is because the DB was actually being started on the default postgres port which is 5432. Turns out in docker-compose.yml you need to add a command to change the default port.

pg-development:
    image: postgres
    environment:
      POSTGRES_USER: root
      POSTGRES_PASSWORD: helloworld
      POSTGRES_DB: test_dev
    ports:
      - "3308:3306"
    volumes:
      - dbdata:/data/db
    networks:
      - dev-network
    healthcheck:
      test: ["CMD-SHELL", "pg_isready -U root -d test_dev"]
      interval: 10s
      timeout: 2s
      retries: 10
    command: -p 3306 // this fixes the issue

回答3:

This is worked for me in docker-compose, one of the container is postgresqldb another one is .net core 3.1 container.

#docker-compose.yml
version: '3.4'

services:

    customerdb:
        image: postgres

    customer.api:
        image: ${DOCKER_REGISTRY-}customerapi
        build:
            context: .
            dockerfile: Customer/Customer.API/Dockerfile

docker-compose.override.yml

customerdb:
    container_name: customerdb
    image: postgres
    restart: always
    environment:
        POSTGRES_PASSWORD: postgres
        POSTGRES_DB: postgres
        POSTGRES_USER: postgres
    ports:
        - 5100:5432
    volumes:
        - ./postgres-data1:/var/lib/postgresql/data 

customer.api:
    container_name: customerapi
    environment:
        - ASPNETCORE_ENVIRONMENT=Development
        - "ConnectionStrings:CustomerConnection=host=host.docker.internal;port=5100;database=CustomerDB;username=postgres;password=postgres"
    depends_on:
        - customerdb
    volumes:
        - ${HOME}/.microsoft/usersecrets/:/root/.microsoft/usersecrets
        - ${HOME}/.aspnet/https:/root/.aspnet/https
    ports:
        - "8000:80"

I used ConnectionStrings:CustomerConnection=host=... because I used to app.config for connection string.

来源：https://stackoverflow.com/questions/61313647/server-in-docker-container-unable-to-connect-to-postgres-database-in-another-doc