Docker (compose) : making knex work with postgres - postgresql

Question

I'm trying to dockerize a NodeJS / PostgreSQL app, but i can't run knex migrations, I'm getting the following error :
Error: connect ECONNREFUSED 172.18.0.2:15432
at TCPConnectWrap.afterConnect [as oncomplete] (net.js:1161:14)
Here is my docker-compose.yml :
version: "3"
services:
app:
build: .
depends_on:
- db
links:
- db
ports:
- "3000:3000"
environment:
POSTGRES_PASSWORD: postgres
POSTGRES_USER: postgres
POSTGRES_DB: users-microservice
DB_HOST: db
db:
image: postgres:10.4-alpine
expose:
- "5432"
ports:
- "15432:5432"
environment:
POSTGRES_PASSWORD: postgres
POSTGRES_USER: postgres
POSTGRES_DB: users-microservice
The Dockerfile for the 'app' service :
FROM node:10.1-alpine
EXPOSE 3000 9229 15432
COPY . /home/app
WORKDIR /home/app
RUN npm install
RUN npm install -g knex
CMD ./scripts/start.sh
and in the start.sh, the following command works :
until PGPASSWORD=$POSTGRES_PASSWORD psql -h "$DB_HOST" -U "$POSTGRES_USER" -c '\d'; do
>&2 echo "Postgres is unavailable - sleeping"
sleep 1
done
>&2 echo "Postgres is up - executing command"
So I can connect to postgres through the CLI, but knex can't, why is that ? Am I getting something wrong, I'm new to Docker ?
Best regards,

Answer 1

I assume you're trying to run a command inside the service app when you see this error message (but maybe you can specify)?
My guess then would be that you're trying to connect to db:15432 from within app. Note, that saying
ports:
- "15432:5432"
only makes sure that you can call the service from your host machine on port 15432. But if you want to call the service db from within app, you still have to use db:5432.

Answer 2

The answer from #the-bass saved me. I'm going to include my docker-compose.yml and knexfile.js files to hopefully make this clearer for people with this issue who find this post.
What I was doing wrong was that I was not setting the host environment variable correctly in my app container. Once I changed it to just use db (the name of my postgres container) and made sure to include the port in my knexfile, all worked.
knexfile.js
require("dotenv").config();
module.exports = {
development: {
client: "pg",
connection: {
host: process.env.DB_HOST,
user: process.env.DB_USER,
password: process.env.DB_PASSWORD,
database: process.env.DB_DATABASE,
port: 5432,
},
pool: {
min: 2,
max: 10,
},
migrations: {
directory: "./data/migrations",
},
},
production: {
client: "pg",
connection: {
host: process.env.DB_HOST,
user: process.env.DB_USER,
password: process.env.DB_PASSWORD,
database: process.env.DB_DATABASE,
port: 5432,
},
pool: {
min: 2,
max: 10,
},
migrations: {
directory: "./data/migrations",
},
},
};
docker-compose.yml
version: "3.7"
services:
db:
image: postgres:12.2
restart: always
ports:
- 5432:5432
volumes:
- my-postgres-data:/var/lib/postgresql/data
environment:
- POSTGRES_USER=me
- POSTGRES_PASSWORD=password
- POSTGRES_DB=my-data
node-app:
image: node:12.16.2
command: sh -c "npm install && npm install -g knex && knex migrate:latest && npm start"
ports:
- 3001:3001
working_dir: /home/node/app
volumes:
- ./:/home/node/app
environment:
- NODE_ENV=development
- DB_HOST=db
- DB_USER=HG
- DB_PASSWORD=password
- DB_DATABASE=my-data
depends_on:
- db
links:
- db
volumes:
my-postgres-data: