PostgreSQL RDS | Create from Snapshot or Create New

Provision either a new enterprise grade PostgreSQL RDS database or create a clone of another database from its snapshot. In this context enterprise grade means

• a 48 long password chosen from a set of 70 characters
• a non predictable master database username string
• a high redundancy multi-availability zone database
• private subnet residency in a non-default VPC (if you so wish)
• behind the scenes encryption at rest
• robust options for backup (maintenance) windows and retention period
• sensible descriptive resource tags

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Module Usage | Create New and/or Cloned RDS DBs

This module will conditionally instantiate from a snapshot depending on whether var.in_clone_snapshot is true or false. If true the RDS ID of the database to clone must be provided. This last available snapshot is chosen as the baseline for creating the cloned database.

    module fresh_db {

        source                 = "devops4me/postgres-rds/aws"
        version                = "1.0.1"

        in_security_group_id = module.security-group.out_security_group_id
        in_db_subnet_ids     = module.vpc-network.out_private_subnet_ids
        in_database_name     = "fresh_db"
    }

    module clone_db {

        source                 = "devops4me/postgres-rds/aws"
        version                = "1.0.1"

        in_clone_snapshot    = true
        in_id_of_db_to_clone = var.in_id_of_db_to_clone

        in_security_group_id = module.security-group.out_security_group_id
        in_db_subnet_ids     = module.vpc-network.out_private_subnet_ids
        in_database_name     = "cloned_db"
    }

The important outputs are the out_database_hostname, out_database_username and the out_database_password.

Look at the integration test for the bells and whistles that terraform demands.

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Inputs

This AWS PostgreSQL database terraform module requires these input variables. Important - the database name must start with a letter (not a digit) and can only contain alphanumerics.

Input Variable	Type	Comment
in_database_name	String	alphanumeric only name to give the new database and it must start with a letter - note that providing a different name causes terraform to create a different database
in_clone_snapshot	Boolean	if true the in_id_of_db_to_clone must be provided and will cause the database to be created from the last available snapshot of the specified database
in_id_of_db_to_clone	String	this ID must be provided if in_clone_snapshot is true causing the database to be created from the last available snapshot
in_security_group_id	String	the security group that will constrain traffic to and from the database
in_db_subnet_ids	List	list of private subnet IDs in at least two availability zones (see example) for housing database instances

Resource Tag Inputs

Most organisations have a mandatory set of tags that must be placed on AWS resources for cost and billing reports. Typically they denote owners and specify whether environments are prod or non-prod.

Input Variable	Variable Description	Input Example
in_ecosystem	the ecosystem (environment) name these resources belong to	my-app-test or kubernetes-cluster
in_timestamp	the timestamp in resource names helps you identify which environment instance resources belong to	1911021435 as $(date +%y%m%d%H%M%S)
in_description	a human readable description usually stating who is creating the resource and when and where	"was created by $USER@$HOSTNAME on $(date)."

Try echo $(date +%y%m%d%H%M%S) to check your timestamp and echo "was created by $USER@$HOSTNAME on $(date)." to check your description. Here is how you can send these values to terraform.

$ export TF_VAR_in_timestamp=$(date +%y%m%d%H%M%S)
$ export TF_VAR_in_description="was created by $USER@$HOSTNAME on $(date)."

Outputs

Output Variable	Type	Comment
out_database_username	String	The first database username prefixed with user_rw_ followed by randomized characters.
out_database_password	String	Robust terraform created 48 character password that includes the allowed special characters
out_clone_db_hostname	String	The addressable hostname of the database that has been cloned from a snapshot
out_fresh_db_hostname	String	The addressable hostname of the newly created (fresh) database