Creating a blue/green deployment

When you create a blue/green deployment, you specify the source DB instance to copy in the deployment. The DB instance you choose is the production DB instance, and it becomes the primary DB instance in the blue environment. This DB instance is copied to the green environment, and RDS configures replication from the DB instance in the blue environment to the DB instance in the green environment.

RDS copies the blue environment's topology to a staging area, along with its configured features. When the blue DB instance has read replicas, the read replicas are copied as read replicas of the green DB instance in the deployment. If the blue DB instance is a Multi-AZ DB instance deployment, then the green DB instance is created as a Multi-AZ DB instance deployment.

Preparing for a blue/green deployment

There are certain steps you must take before you create a blue/green deployment, depending on the engine that your DB instance is running.

Preparing an RDS for MySQL DB instance for a blue/green deployment

Before you create a blue/green deployment for an RDS for MySQL DB instance, you must enable automated backups. For instructions, see Enabling automated backups.

Preparing an RDS for PostgreSQL DB instance for a blue/green deployment

Before you create a blue/green deployment for an RDS for PostgreSQL DB instance, make sure to do the following:

Specifying changes when creating a blue/green deployment

You can make the following changes to the DB instance in the green environment when you create the blue/green deployment.

You can make other modifications to the DB instance in the green environment after it is deployed. For example, you might make schema changes to your database or change the DB instance class used by one or more DB instances in the green environment.

For information about modifying a DB instance, see Modifying an Amazon RDS DB instance.

Specify a higher engine version

You can specify a higher engine version if you want to test a DB engine upgrade. Upon switchover, the database is upgraded to the major or minor DB engine version that you specify.

Specify a different DB parameter group

You can test how parameter changes affect the DB instances in the green environment or specify a parameter group for a new major DB engine version in the case of an upgrade.

If you specify a different DB parameter group, the specified DB parameter group is associated with all of the DB instances in the green environment. If you don't specify a different parameter group, each DB instance in the green environment is associated with the parameter group of its corresponding blue DB instance.

Enable RDS Optimized Writes

You can use Blue/Green Deployments to upgrade to a DB instance class that supports RDS Optimized Writes. You can only enable RDS Optimized Writes on a database that was created with a supported DB instance class. Thus, this option creates a green database that uses a supported DB instance class, which enables you to turn on RDS Optimized Writes on the green DB instance.

If you're upgrading from a DB instance class that doesn't support RDS Optimized Writes to one that does, you must also upgrade the storage configuration of the green DB instance. For more information, see Upgrade the storage configuration.

You can only upgrade the DB instance class of the primary green DB instance. By default, read replicas in the green environment inherit the DB instance settings from the blue environment. After the green environment is successfully created, you must manually modify the DB instance class of the read replicas in the green environment.

Some instance class upgrades aren't supported depending on the engine version and instance class of the blue DB instance. For more information about DB instance classes, see DB instance classes.

Upgrade the storage configuration

If your blue database isn't on the latest storage configuration, RDS can migrate the green DB instance from the older storage configuration (32-bit file system) to the preferred configuration. You can use RDS Blue/Green Deployments to overcome the scaling limitations on storage and file size for older 32-bit file systems. In addition, this setting changes the storage configuration to be compatible with RDS Optimized Writes if the specified DB instance class supports Optimized Writes.

This option is only available if your blue database is not on the latest storage configuration, or if you're changing the DB instance class within the same request.

Handling lazy loading when you create a blue/green deployment

When you create a blue/green deployment, Amazon RDS creates the primary DB instance in the green environment by restoring from a DB snapshot. After it is created, the green DB instance continues to load data in the background, which is known as lazy loading. If the DB instance has read replicas, these are also created from DB snapshots and are subject to lazy loading.

If you access data that hasn't been loaded yet, the DB instance immediately downloads the requested data from Amazon S3, and then continues loading the rest of the data in the background. For more information, see Amazon EBS snapshots.

To help mitigate the effects of lazy loading on tables to which you require quick access, you can perform operations that involve full-table scans, such as SELECT *. This operation allows Amazon RDS to download all of the backed-up table data from S3.

If an application attempts to access data that isn't loaded, the application can encounter higher latency than normal while the data is loaded. This higher latency due to lazy loading could lead to poor performance for latency-sensitive workloads.

Creating a blue/green deployment

You can create a blue/green deployment using the Amazon Web Services Management Console, the Amazon CLI, or the RDS API.

aws rds create-blue-green-deployment \
    --blue-green-deployment-name my-blue-green-deployment \
    --source arn:aws:rds:us-east-2:123456789012:db:mydb1 \
    --target-engine-version 8.0.31 \
    --target-db-parameter-group-name mydbparametergroup \
    --target-db-instance-class db.m5.8xlarge \
    --upgrade-target-storage-config

aws rds create-blue-green-deployment ^
    --blue-green-deployment-name my-blue-green-deployment ^
    --source arn:aws:rds:us-east-2:123456789012:db:mydb1 ^
    --target-engine-version 8.0.31 ^
    --target-db-parameter-group-name mydbparametergroup ^
    --target-db-instance-class db.m5.8xlarge ^
    --upgrade-target-storage-config