How to find my database host address for CI / CD? - postgresql

Question

I'm going to conduct CI / CD in gitlab in AWS. My website contains a Postgresql database.
Question 1: But I don't know how to find the db host. Some say the host name is localhost, but I doubt it because I've deployed my website to AWS. Should it be elastic IP?
My .gitlab-ci.yml file is as follows:
image: node:latest
stages:
- testing
variables:
POSTGRES_DB: firstdb
POSTGRES_USER: johndoe
POSTGRES_PASSWORD: 1234
POSTGRES_HOST: //I don't know
testing:
services:
- postgres:latest
before_script:
- npm install -g yarn
- yarn install
- yarn knex migrate:latest --env testing
stage: testing
script:
- yarn jest
Question 2: Also, should I change the database config of development, testing and production of knex.ts accordingly, so that it aligns with .gitlab-ci.yml?
My knex file is as follows:
import * as dotenv from 'dotenv';
dotenv.config();
module.exports = {
development: {
client: 'postgresql',
connection: {
database: process.env.DB_NAME , //should I type actual data?
user: process.env.DB_USERNAME ,
password: process.env.DB_PASSWORD
},
pool: {
min: 2,
max: 10
},
migrations: {
tableName: 'knex_migrations'
}
},
testing:{
client: 'postgresql',
connection: {
host: process.env.POSTGRES_HOST ,//should I type actual data?
database: process.env.POSTGRES_DB ,
user: process.env.POSTGRES_USER ,
password: process.env.POSTGRES_PASSWORD
},
pool: {
min: 2,
max: 10
},
migrations: {
tableName: 'knex_migrations'
}
},
production: {
client: "postgresql",
connection: {
database: process.env.DB_NAME ,//should I type actual data?
user: process.env.DB_USERNAME ,
password: process.env.DB_PASSWORD
},
pool: {
min: 2,
max: 10
},
migrations: {
tableName: "knex_migrations"
}
}
};
Many thanks in advance. :)

Answer 1

The hostname is postgres. the hostname is derived from the image name.
explained here:
https://docs.gitlab.com/ee/ci/docker/using_docker_images.html#how-services-are-linked-to-the-job