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 and features to a staging area. If the blue DB instance has read replicas, they are copied as replicas of the green instance. The allocated storage of all green replicas matches the green primary instance, while other storage parameters are inherited from the blue replicas.

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 or RDS for MariaDB DB instance for a blue/green deployment

Before you create a blue/green deployment for an RDS for MySQL or RDS for MariaDB 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 with physical replication

Before you create an RDS for PostgreSQL blue/green deployment that uses physical replication, you must enable automated backups. For instructions, see Enabling automated backups.

For a list of versions that use physical replication versus logical replication, see PostgreSQL replication methods for blue/green deployments.

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

Before you create an RDS for PostgreSQL blue/green deployment that uses logical replication, make sure to do the following. For a list of versions that use logical replication versus physical replication, see PostgreSQL replication methods for blue/green deployments.

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 specify a higher engine version or a different parameter group.

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.

Modify storage and performance settings

Adjust storage and performance settings in the green environment to optimize resource allocation. These settings include allocated storage, provisioned IOPS, storage type, and storage throughput (for gp3 storage).

You can change the storage type of the green DB instance to gp2, gp3, io1, or io2. For gp3 storage, you can also adjust storage throughput to enhance data transfer performance for high-demand workloads, or to reduce costs for less intensive applications. For more information, see Amazon RDS DB instance storage.

You can also choose to increase or decrease allocated storage in the green environment. However, a storage reduction only occurs if the target allocated storage is at least 20% more than the current storage usage. If you decrease the allocated storage, Amazon RDS initiates a storage configuration upgrade. For more information, see Upgrade the storage configuration.

If the blue DB instance uses magnetic storage, you must change the green DB instance to a General Purpose or Provisioned IOPS storage type in order to increase or decrease the allocated storage.

Enable RDS Optimized Writes

You can use a blue/green deployment 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. You can only upgrade the storage configuration when initially creating a blue/green deployment.

Lazy loading and storage initialization for blue/green deployments

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's created, the green DB instance and its read replicas continue to load data in the background through a process known as lazy loading.

Lazy loading only loads data blocks as applications request them. If you attempt to access data that hasn't been loaded yet, Amazon EBS immediately retrieves it from Amazon S3, while remaining data continues to load in the background. For more information, see Amazon EBS snapshots.

To accelerate full volume performance, Amazon RDS provides storage initialization, which reads all blocks in the green environment volume. Amazon EBS proactively downloads blocks from Amazon S3, providing maximum volume performance from the first use. Storage initialization occurs entirely in the background, ensuring no impact on your DB instance availability or ongoing activities, such as patching or upgrades.

Storage initialization is available only for instances in blue/green deployments with gp2, gp3, io1, and io2 volume types. It supports all instance classes except the t3 and t4 families. If you modify a green DB instance in a Single-AZ deployment to a Multi-AZ DB instance deployment, storage initialization includes the secondary node in the Multi-AZ configuration.

During storage initialization, the instance remains fully available and usable for database operations, though storage might not reach full performance until initialization completes. While the storage initialization is underway, the overall instance status changes to Storage-initialization, and the progress indicator reflects the minimum initialization level across all volumes of the DB instance.

Use the console, Amazon CLI, or Amazon RDS API to monitor storage initialization.

The progress indicator updates as the background initialization job advances, allowing you to track storage readiness before full storage initialization completes. Storage initialization enables optimized performance as your green DB instance becomes fully operational.

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

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

Settings for creating blue/green deployments

The following table explains the settings that you can choose when you create a blue/green deployment. For more information about the Amazon CLI options, see create-blue-green-deployment. For more information about the RDS API parameters, see CreateBlueGreenDeployment.