00_db_instance_provisioning.py

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# © 2026 Voltaire Bazurto Blacio. All rights reserved.
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import boto3
from botocore.exceptions import ClientError
import secrets
import string

AWS_PROFILE = "default"
AWS_REGION = 'us-east-1'
DB_MASTER_USERNAME = 'postgres'
DB_INSTANCE_ID = 'hr-recruit-app-demo-aws'
DB_NAME = 'hr_recruit_app'

def generate_password():
    alphabet = string.ascii_letters + string.digits + '.$' #support alphanumeric characters and only a subset of allowed special chars
    password = ''.join(secrets.choice(alphabet) for _ in range(20))
    return password

def create_db_instance_if_not_exist(rds_client, master_pwd):
    return rds_client.create_db_instance(
    DBInstanceClass='db.t4g.micro',
    DBInstanceIdentifier=DB_INSTANCE_ID,
    Engine='postgres',
    EngineVersion='17.6',
    DBName=DB_NAME,
    AllocatedStorage=20, #Min size for gp2 is 20G
    MasterUsername=DB_MASTER_USERNAME,
    MasterUserPassword=master_pwd,
    )

# main script starts here
rds = boto3.client('rds', region_name=AWS_REGION)
DB_MASTER_USER_PASSWORD = generate_password()
try:
  db_instance_result = create_db_instance_if_not_exist(rds, DB_MASTER_USER_PASSWORD)
  print(f"New DB instance {DB_INSTANCE_ID} created with details: ")
  print(f"Copy this value in a safe place: {DB_MASTER_USER_PASSWORD}\n")
except ClientError as e:
  if 'instance already exists' in e.args[0] :
      print(f'DB Instance already exists in RDS. Skipping DB creation')
  else:
      print(f'Error creating DB instance: {e}')
      exit(1)
except Exception as e:
  print(f'Error creating DB instance: {e}')
  exit(1)


# List db instances
print('########### List of dbs in RDS ############')
dbs = rds.describe_db_instances()
for db in dbs['DBInstances']:
    print(f'{db['DBInstanceIdentifier']} - {db['DBName']} - {db['Engine']}')

#Wait until instance is ready
waiter = rds.get_waiter('db_instance_available')
print(f"Waiting for RDS instance '{DB_INSTANCE_ID}' to be available...\n")

try:
    waiter.wait(DBInstanceIdentifier=DB_INSTANCE_ID, WaiterConfig={
        'Delay': 30,
        'MaxAttempts': 60,
    })

    print(f"RDS instance '{DB_INSTANCE_ID}' is now [available]!\n")
except Exception as e:
    print(f'Error waiting for RDS instance: {e}\n')
    raise