ECONNREFUSED for Postgres on nodeJS with dockers

I'm building an app running on NodeJS using postgresql. I'm using SequelizeJS as ORM. To avoid using real postgres daemon and having nodejs on my own device, i'm using containers with docker-compose.

when I run docker-compose up it starts the pg database

database system is ready to accept connections

and the nodejs server. but the server can't connect to database.

Error: connect ECONNREFUSED 127.0.01:5432

If I try to run the server without using containers (with real nodejs and postgresd on my machine) it works.

But I want it to work correctly with containers. I don't understand what i'm doing wrong.

here is the docker-compose.yml file

web:
  image: node
  command: npm start
  ports:
    - "8000:4242"
  links:
    - db
  working_dir: /src
  environment:
    SEQ_DB: mydatabase
    SEQ_USER: username
    SEQ_PW: pgpassword
    PORT: 4242
    DATABASE_URL: postgres://username:[email protected]:5432/mydatabase
  volumes:
    - ./:/src
db:
  image: postgres
  ports:
  - "5432:5432"
  environment:
    POSTGRES_USER: username
    POSTGRES_PASSWORD: pgpassword

Could someone help me please?

(someone who likes docker :) )

Solution 1:

Your DATABASE_URL refers to 127.0.0.1, which is the loopback adapter (more here). This means "connect to myself".

When running both applications (without using Docker) on the same host, they are both addressable on the same adapter (also known as localhost).

When running both applications in containers they are not both on localhost as before. Instead you need to point the web container to the db container's IP address on the docker0 adapter - which docker-compose sets for you.

Change:

127.0.0.1 to CONTAINER_NAME (e.g. db)

Example:

DATABASE_URL: postgres://username:[email protected]:5432/mydatabase

to

DATABASE_URL: postgres://username:pgpassword@db:5432/mydatabase

This works thanks to Docker links: the web container has a file (/etc/hosts) with a db entry pointing to the IP that the db container is on. This is the first place a system (in this case, the container) will look when trying to resolve hostnames.

Solution 2:

For further readers, if you're using Docker desktop for Mac use host.docker.internal instead of localhost or 127.0.0.1 as it's suggested in the doc. I came across same connection refused... problem. Backend api-service couldn't connect to postgres using localhost/127.0.0.1. Below is my docker-compose.yml and environment variables as a reference:

version: "2"

services:
  api:
    container_name: "be"
    image: <image_name>:latest
    ports:
      - "8000:8000"
    environment:
      DB_HOST: host.docker.internal
      DB_USER: <your_user>
      DB_PASS: <your_pass>
    networks: 
      - mynw

  db:
    container_name: "psql"
    image: postgres
    ports:
      - "5432:5432"
    environment:
      POSTGRES_DB: <your_postgres_db_name>
      POSTGRES_USER: <your_postgres_user>
      POSTGRES_PASS: <your_postgres_pass>
    volumes:
      - ~/dbdata:/var/lib/postgresql/data
    networks:
      - mynw

Solution 3:

If you send database vars separately. You can assign a database host.

DB_HOST=<POSTGRES_SERVICE_NAME> #in your case "db" from docker-compose file.

Solution 4:

I had two containers one called postgresdb, and another call node

I changed my node queries.js from:

const pool = new Pool({
    user: 'postgres',
    host: 'localhost',
    database: 'users',
    password: 'password',
    port: 5432,
})

To

const pool = new Pool({
    user: 'postgres',
    host: 'postgresdb',
    database: 'users',
    password: 'password',
    port: 5432,
})

All I had to do was change the host to my container name ["postgresdb"] and that fixed this for me. I'm sure this can be done better but I just learned docker compose / node.js stuff in the last 2 days.

Solution 5:

If none of the other solutions worked for you, consider manual wrapping of PgPool.connect() with retry upon having ECONNREFUSED:

const pgPool = new Pool(pgConfig);
const pgPoolWrapper = {
    async connect() {
        for (let nRetry = 1; ; nRetry++) {
            try {
                const client = await pgPool.connect();
                if (nRetry > 1) {
                    console.info('Now successfully connected to Postgres');
                }
                return client;
            } catch (e) {
                if (e.toString().includes('ECONNREFUSED') && nRetry < 5) {
                    console.info('ECONNREFUSED connecting to Postgres, ' +
                        'maybe container is not ready yet, will retry ' + nRetry);
                    // Wait 1 second
                    await new Promise(resolve => setTimeout(resolve, 1000));
                } else {
                    throw e;
                }
            }
        }
    }
};

(See this issue in node-postgres for tracking.)