Automatic RDS scaling

Scale RDS replice instance in blue/green transferring momentarily the connection to master database

Lambda functions are invoked by CloudWatch cron-scheduled event in this sequence

08:00 routingToMaster
08:05 scaleUp
08:15 routingToReplica

15:00 routingToMaster
15:05 scaleDown
15:15 routingToReplica

this configuration give to RDS replica 10 minute for complete the scaling process and then re-pointing DNS to replica endpoint. Is assumed the DNS propagation take around 5 minute.

Times are based on GMT+0 time zone.

Getting Start

Serverless

Follow documentation at https://serverless.com/framework/docs/providers/aws/guide/intro/ to edit settings. A makefile is provided with deploy, invoke and logs command wrapping serverless commands.

Environment variables

Before launch commands create a file credentials (renaming credentials.sample) with correct AWS CLI profile to use declared in ~/.aws/credentials.

# AWS Credentials
export AWS_PROFILE = <aws profile>

Create a file environment (renaming environment.sample) with the the project's settings values

# AWS
export ENVIRONMENT = <stage | prod>
export AWS_REGION = <aws region>
export AWS_ACCOUNT_ID = <aws account id>

# DNS
export HostedZoneId =
export RecordName =
export MasterEndpoint =
export ReplicaEndpoint =

# Database
export InstanceIdentifier =
export InstanceClassSmall =
export InstanceClassBig =

Deploy

Use a make command to deploy make deploy

Debug

Get function log make logs func="test"

Invoke function remotly make invoke func="test"