ECONNREFUSED for Postgres on nodeJS with dockers
node.jsPostgresqlDockersequelize.jsnode.js Problem Overview
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 :) )
node.js Solutions
Solution 1 - node.js
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 - node.js
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 - node.js
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 - node.js
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 - node.js
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.)
Solution 6 - node.js
As mentioned here.
> Each container can now look up the hostname web
or db
and get back the appropriate container’s IP address. For example, web
’s application code could connect to the URL postgres://db:5432
and start using the Postgres database.
> It is important to note the distinction between HOST_PORT
and CONTAINER_PORT
. In the above example, for db
, the HOST_PORT
is 8001
and the container port is 5432
(postgres default). Networked service-to-service communication uses the CONTAINER_PORT
. When HOST_PORT
is defined, the service is accessible outside the swarm as well.
> Within the web
container, your connection string to db
would look like postgres://db:5432
, and from the host machine, the connection string would look like postgres://{DOCKER_IP}:8001
.
So DATABASE_URL
should be postgres://username:pgpassword@db:5432/mydatabase
Solution 7 - node.js
I am here with a tiny modification about handle this.
As Andy say in him response.
- "you need to point the
web
container to thedb
container's"
And taking in consideration the official documentation about docker-compose link's
- "Links are not required to enable services to communicate - by default, any service can reach any other service at that service’s name."
Because of that, you can keep your docker_compose.yml in this way:
docker_compose.yml
version: "3"
services:
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
DATABASE_URL: "postgres://username:pgpassword@db:5432/mydatabase"
volumes:
- ./:/src
db:
image: postgres
ports:
- "5432:5432"
environment:
POSTGRES_USER: username
POSTGRES_PASSWORD: pgpassword
But it is a kinda cool way to be verbose while we are coding. So, your approach it is nice.