Connect the AWS Relational Database Service (RDS) from EC2 Instance

Creating an EC2 instance and connecting the RDS PostgreSQL DB instance.

Considering the below instances are already created,
1. RDS PostgreSQL DB instance ( Refer to this article)
2. EC2 Instance

Connect to EC2 instance using ssh client:

1. Open an SSH client.
2. Locate your private key file. The key used to launch this instance is {permissionkey}.pem
3. Connect to your instance using its Public DNS: {public dns}
Example:
ssh -i “{permissionkey}.pem” ubuntu@{public dns}

Once the ssh client is connected, then update OS and install the PostgreSQL client.

sudo apt-get update && sudo apt-get upgrade
sudo apt-get purge postgresql*
sudo apt-get -f install
sudo apt-get install postgresql

Connect PostgreSQL client,

root@ip-{ip address}:/home/ubuntu# psql — host={RDS Endpoint} — port=5432 — username={user name of RDS DB instance} — password — dbname=test_db

Then, enter the password of the RDS DB instance

Once connected to the PostgreSQL client, you will be able to access the test_db database.

test_db=> create table departments(id integer, name varchar);
CREATE TABLE

test_db=> INSERT INTO departments(id, name) values (1, ‘IT’);
INSERT 0 1

test_db=> SELECT * FROM departments;
id | name
— — + — — —
1 | IT
(1 row)

test_db=> create table users(id integer, name varchar, department varchar);
CREATE TABLE

test_db=> INSERT INTO users(id, name, department) values(1, ‘Amol’, 1);
INSERT 0 1

test_db=> SELECT * FROM users;
id | name | department
— — + — — — + — — — — — —
1 | Amol | 1
(1 row)

You can connect RDS DB Instance using the DB Tool as well, https://docs.aws.amazon.com/AmazonRDS/latest/UserGuide/CHAP_GettingStarted.CreatingConnecting.PostgreSQL.html