terraform-aws-rds-postgres

Terraform module which creates an AWS RDS Postgres.

Requirements

• An existing VPC
• An existing DB subnet group
• An existing Postgres parameter group
• An existing RDS Enhanced Monitoring role
• Existing DB security groups

Password for Master DB

• The module will generate a random 16 characters long password.
• The module will output this password.
• Make sure that you change the password after the provisioning is successfully completed.

Read Replica

If replicate_source_db parameter is defined, it indicates that the instance is meant to be a read replica.

These parameters will be inherited from the master's in the first creation stage:

1. allocated_storage
2. maintenance_window
3. parameter_group_name
4. vpc_security_group_ids

To apply different values for the parameters above, you have to re-apply the configuration after the first creation is finished.

Some default values are changed for read replica instance:

• backup_retention_period = 0 Postgres read replica does not support automated backup.

• skip_final_snapshot = true When deleting a read replica, a final snapshot cannot be created.

• copy_tags_to_snapshot = false When deleting a read replica, a final snapshot is not created.

How to promote a read replica?

These steps need to be done in sequence:

1. Remove parameter replicate_source_db This is to indicate that the instance is meant to be a master instance.

2. Add parameter backup_retention_period = 0 We need to explicitly disable automated backup for now, otherwise Terraform will complain that a read replica does not support automated backup.

3. Apply the configuration and wait for db instance to be successfully promoted to master

4. Remove parameter availability_zone We are using multi_az parameter for master instance.

5. Modify parameter multi_az This is to enable multi AZ. Either set it explicitly or leave as default.

6. Modify parameter backup_retention_period This is to enable automated backup. Either set it explicitly or leave as default.

7. Add parameter backup_window Either set it explicitly or leave as default.

8. Modify other parameters as you would to a master instance

9. Apply the configuration again

Usage

module "postgres" {
  source  = "github.com/traveloka/terraform-aws-rds-postgres?ref=v0.2.0"

  product_domain = "txt"
  service_name   = "txtinv"
  environment    = "production"
  description    = "Postgres to store Transport Extranet (txt) inventory data"

  instance_class = "db.t2.small"
  engine_version = "9.6.6"

  allocated_storage = 100

  multi_az = true

  # Change to valid security group id
  vpc_security_group_ids = [
    "sg-50036436"
  ]

  # Change to valid db subnet group name
  db_subnet_group_name = "tvlk-dev-rds-subnet-group"

  # Change to valid parameter group name
  parameter_group_name = "default.postgres9.6"

  maintenance_window      = "Mon:00:00-Mon:03:00"
  backup_retention_period = 0

  skip_final_snapshot = true

  # Change to valid monitoring role arn
  monitoring_role_arn = "arn:aws:iam::517530806209:role/rds-monitoring-role"

  # Change to valid route 53 zone id
  route53_zone_id = "Z32OEBZ2VZHSJZ"
}

Authors

• Andy Saputra

License

Apache 2 Licensed. See LICENSE for full details.