RDS

Amazon Relational Database Service for managing relational database instances and clusters.

For the Aurora HTTP SQL endpoint, see the RDS Data API, an opt-in service backed by a real PostgreSQL via Docker.

Configuration

Property	Value
Protocol	`AwsQuery`
Signing Name	`rds`
Persistence	Yes

RDS uses the AwsQuery protocol: POST requests with Content-Type: application/x-www-form-urlencoded and an Action= parameter.

Quick Start

Create a database instance, describe it, and stop it:

bash

# Create a DB instance
aws --endpoint-url http://localhost:4566 \
  rds create-db-instance \
  --db-instance-identifier mydb \
  --db-instance-class db.t3.micro \
  --engine mysql \
  --master-username admin \
  --master-user-password password123 \
  --allocated-storage 20 \
  --db-name myappdb

# Describe the instance
aws --endpoint-url http://localhost:4566 \
  rds describe-db-instances \
  --db-instance-identifier mydb

# Stop the instance
aws --endpoint-url http://localhost:4566 \
  rds stop-db-instance \
  --db-instance-identifier mydb

Operations

DB Instances

CreateDBInstance — create a new database instance
- Input: DBInstanceIdentifier (required, unique name), DBInstanceClass (e.g., db.t3.micro, db.r5.large), Engine (mysql, postgres, mariadb, oracle-se2, sqlserver-se, aurora-mysql, aurora-postgresql), MasterUsername, MasterUserPassword, AllocatedStorage (GB), DBName, VpcSecurityGroupIds, DBSubnetGroupName, PubliclyAccessible, MultiAZ, EngineVersion, StorageType (gp2, io1, standard)
- Returns: DBInstance with DBInstanceIdentifier, DBInstanceStatus (creating → available), Endpoint ({Address, Port}), DBInstanceArn
- Aurora engines require a DBClusterIdentifier naming an existing cluster. The instance joins that cluster's member list and inherits its master username, engine version, and storage; the first instance to join is the writer and later instances are read replicas.
DeleteDBInstance — delete a database instance
- Input: DBInstanceIdentifier, optional SkipFinalSnapshot, FinalDBSnapshotIdentifier
DescribeDBInstances — list database instances with optional filter
- Input: optional DBInstanceIdentifier, Filters, MaxRecords, Marker
- Returns: paginated DBInstances list
ModifyDBInstance — update instance configuration (class, storage, multi-AZ, etc.)
- Input: DBInstanceIdentifier, optional DBInstanceClass, AllocatedStorage, ApplyImmediately, BackupRetentionPeriod, PreferredMaintenanceWindow
StartDBInstance — start a stopped database instance
- Input: DBInstanceIdentifier
- Status transitions: stopped → starting → available
StopDBInstance — stop a running database instance
- Input: DBInstanceIdentifier
- Status transitions: available → stopping → stopped
RebootDBInstance — reboot a database instance (useful after parameter group changes)
- Input: DBInstanceIdentifier, optional ForceFailover

DB Clusters (Aurora)

CreateDBCluster — create an Aurora database cluster
- Input: DBClusterIdentifier, Engine (aurora, aurora-mysql, aurora-postgresql), MasterUsername, MasterUserPassword, DatabaseName, VpcSecurityGroupIds, optional EngineMode, ServerlessV2ScalingConfiguration ({MinCapacity, MaxCapacity}), EnableHttpEndpoint
- Returns: DBCluster with DBClusterIdentifier, Status, Endpoint, ReaderEndpoint, EngineMode, HttpEndpointEnabled, AssociatedRoles
DeleteDBCluster — delete a database cluster
- Input: DBClusterIdentifier, optional SkipFinalSnapshot
- Rejected with InvalidParameterCombination when the cluster has deletion protection enabled
DescribeDBClusters — list database clusters with optional filter
- Input: optional DBClusterIdentifier, Filters, MaxRecords, Marker
ModifyDBCluster updates a cluster's configuration
- Input: DBClusterIdentifier, optional BackupRetentionPeriod, PreferredBackupWindow, PreferredMaintenanceWindow, Port, EngineVersion, VpcSecurityGroupIds, DeletionProtection, ApplyImmediately
- DeletionProtection, PreferredMaintenanceWindow, and security groups apply immediately; the rest follow ApplyImmediately, staging under PendingModifiedValues and flushing during the maintenance window when deferred
StartDBCluster starts a stopped cluster and its member instances
- Input: DBClusterIdentifier
- Status transitions: stopped to available
StopDBCluster stops a running cluster and its member instances
- Input: DBClusterIdentifier
- Status transitions: available to stopped
RebootDBCluster reboots a cluster
- Input: DBClusterIdentifier
FailoverDBCluster promotes a reader to writer
- Input: DBClusterIdentifier, optional TargetDBInstanceIdentifier (promotes the named member, otherwise the next reader)
ModifyDBCluster also accepts ServerlessV2ScalingConfiguration and EnableHttpEndpoint, applied immediately
AddRoleToDBCluster associates an IAM role with the cluster
- Input: DBClusterIdentifier, RoleArn, optional FeatureName
RemoveRoleFromDBCluster detaches an IAM role from the cluster
- Input: DBClusterIdentifier, RoleArn, optional FeatureName
EnableHttpEndpoint / DisableHttpEndpoint toggle the RDS Data API HTTP endpoint
- Input: ResourceArn (the cluster ARN)

DB Subnet Groups

CreateDBSubnetGroup — create a subnet group for database placement
- Input: DBSubnetGroupName, DBSubnetGroupDescription, SubnetIds (list)
DeleteDBSubnetGroup — delete a subnet group
DescribeDBSubnetGroups — list subnet groups
- Input: optional DBSubnetGroupName, Filters

DB Parameter Groups

CreateDBParameterGroup — create a parameter group for database configuration
- Input: DBParameterGroupName, DBParameterGroupFamily (e.g., mysql8.0, postgres15), Description
DeleteDBParameterGroup — delete a parameter group
DescribeDBParameterGroups — list parameter groups

DB Cluster Parameter Groups (Aurora)

CreateDBClusterParameterGroup creates a cluster-level parameter group
- Input: DBClusterParameterGroupName, DBParameterGroupFamily (e.g., aurora-postgresql16, aurora-mysql8.0), Description
DescribeDBClusterParameterGroups lists cluster parameter groups
- Input: optional DBClusterParameterGroupName
DeleteDBClusterParameterGroup deletes a cluster parameter group
- Input: DBClusterParameterGroupName
DescribeDBClusterParameters returns the resolved parameter list for a group
- Input: DBClusterParameterGroupName, optional Source (user or engine-default)
- Returns: engine defaults for the family with caller overrides applied, each tagged with its Source
ModifyDBClusterParameterGroup overrides one or more parameter values
- Input: DBClusterParameterGroupName, Parameters (list of {ParameterName, ParameterValue, ApplyMethod})
ResetDBClusterParameterGroup returns parameters to their engine defaults
- Input: DBClusterParameterGroupName, optional ResetAllParameters, Parameters

DB Snapshots

CreateDBSnapshot — create a snapshot from an existing instance
- Input: DBSnapshotIdentifier, DBInstanceIdentifier
- Returns: DBSnapshot with Status (available) immediately
DeleteDBSnapshot — delete a snapshot
- Input: DBSnapshotIdentifier
DescribeDBSnapshots — list snapshots with optional filter
- Input: optional DBSnapshotIdentifier, DBInstanceIdentifier
- Returns: DBSnapshots list
CopyDBSnapshot — copy snapshot metadata to a new identifier (stub)
- Input: SourceDBSnapshotIdentifier, TargetDBSnapshotIdentifier
RestoreDBInstanceFromDBSnapshot rebuilds an instance from a snapshot
- Input: DBInstanceIdentifier, DBSnapshotIdentifier, optional DBInstanceClass, StorageType, MultiAZ, PubliclyAccessible, DBSubnetGroupName, VpcSecurityGroupIds
- Engine, version, storage, master username, and encryption are inherited from the snapshot

DB Cluster Snapshots (Aurora)

CreateDBClusterSnapshot creates a manual snapshot of an Aurora cluster
- Input: DBClusterSnapshotIdentifier, DBClusterIdentifier, optional Tags
- Returns: DBClusterSnapshot with Status (available), inheriting the cluster's engine, version, and master username
DescribeDBClusterSnapshots lists cluster snapshots with optional filters
- Input: optional DBClusterSnapshotIdentifier, DBClusterIdentifier, SnapshotType, MaxRecords, Marker
DeleteDBClusterSnapshot deletes a cluster snapshot
- Input: DBClusterSnapshotIdentifier
CopyDBClusterSnapshot copies a cluster snapshot to a new identifier
- Input: SourceDBClusterSnapshotIdentifier, TargetDBClusterSnapshotIdentifier, optional KmsKeyId, SourceRegion, Tags
RestoreDBClusterFromSnapshot rebuilds an Aurora cluster from a cluster snapshot
- Input: DBClusterIdentifier, SnapshotIdentifier, Engine, optional EngineVersion, VpcSecurityGroupIds, BackupRetentionPeriod, DeletionProtection
- The restored cluster inherits the snapshot's engine version and master username and starts with no members

Engine Versions & Options

DescribeDBEngineVersions returns available engine versions for postgres, mysql, mariadb, aurora-postgresql, and aurora-mysql
- Input: optional Engine, EngineVersion filters
- Returns: list of engine versions with DBParameterGroupFamily, Status, and Aurora capability flags (SupportsGlobalDatabases, SupportsParallelQuery)
DescribeOrderableDBInstanceOptions returns available instance classes per engine
- Input: Engine, optional EngineVersion
- Returns: instance classes with their storage type options. Aurora engines return cluster-capable classes (including db.serverless) backed by aurora storage and report SupportsClusters; standalone engines return db.t3.micro through db.r5.4xlarge on gp2/io1/standard storage

DB Cluster Endpoints

DescribeDBClusterEndpoints — list writer, reader, and custom cluster endpoints
- Input: optional DBClusterIdentifier, DBClusterEndpointIdentifier
CreateDBClusterEndpoint — create a custom cluster endpoint
- Input: DBClusterIdentifier, DBClusterEndpointIdentifier, EndpointType
DeleteDBClusterEndpoint — delete a custom cluster endpoint
- Input: DBClusterEndpointIdentifier

Stubs

DescribeEventSubscriptions — returns empty list
DescribeDBLogFiles — returns empty list

Curl Examples

bash

# 1. Create a PostgreSQL instance
curl -s -X POST http://localhost:4566 \
  -H "Content-Type: application/x-www-form-urlencoded" \
  -H "Authorization: AWS4-HMAC-SHA256 Credential=test/20260421/us-east-1/rds/aws4_request, SignedHeaders=host, Signature=fake" \
  --data-urlencode 'Action=CreateDBInstance' \
  --data-urlencode 'DBInstanceIdentifier=mypostgres' \
  --data-urlencode 'DBInstanceClass=db.t3.small' \
  --data-urlencode 'Engine=postgres' \
  --data-urlencode 'MasterUsername=dbadmin' \
  --data-urlencode 'MasterUserPassword=SuperSecret123!' \
  --data-urlencode 'AllocatedStorage=20' \
  --data-urlencode 'DBName=appdb' \
  --data-urlencode 'EngineVersion=15.4'

# 2. Describe all instances
curl -s -X POST http://localhost:4566 \
  -H "Content-Type: application/x-www-form-urlencoded" \
  -H "Authorization: AWS4-HMAC-SHA256 Credential=test/20260421/us-east-1/rds/aws4_request, SignedHeaders=host, Signature=fake" \
  --data-urlencode 'Action=DescribeDBInstances'

# 3. Tag an instance
curl -s -X POST http://localhost:4566 \
  -H "Content-Type: application/x-www-form-urlencoded" \
  -H "Authorization: AWS4-HMAC-SHA256 Credential=test/20260421/us-east-1/rds/aws4_request, SignedHeaders=host, Signature=fake" \
  --data-urlencode 'Action=AddTagsToResource' \
  --data-urlencode 'ResourceName=arn:aws:rds:us-east-1:000000000000:db:mydb' \
  --data-urlencode 'Tags.member.1.Key=environment' \
  --data-urlencode 'Tags.member.1.Value=staging'

SDK Example

typescript

import {
  RDSClient,
  CreateDBInstanceCommand,
  DescribeDBInstancesCommand,
  ModifyDBInstanceCommand,
  StopDBInstanceCommand,
} from '@aws-sdk/client-rds';

const rds = new RDSClient({
  region: 'us-east-1',
  endpoint: 'http://localhost:4566',
  credentials: { accessKeyId: 'test', secretAccessKey: 'test' },
});

// Create DB instance
const { DBInstance } = await rds.send(new CreateDBInstanceCommand({
  DBInstanceIdentifier: 'mydb',
  DBInstanceClass: 'db.t3.micro',
  Engine: 'mysql',
  MasterUsername: 'admin',
  MasterUserPassword: 'password123',
  AllocatedStorage: 20,
  DBName: 'myapp',
  Tags: [{ Key: 'environment', Value: 'staging' }],
}));

console.log('Instance ID:', DBInstance?.DBInstanceIdentifier);
console.log('Status:', DBInstance?.DBInstanceStatus); // creating
console.log('ARN:', DBInstance?.DBInstanceArn);

// Describe instances
const { DBInstances } = await rds.send(new DescribeDBInstancesCommand({
  DBInstanceIdentifier: 'mydb',
}));

const instance = DBInstances?.[0];
console.log('Endpoint:', instance?.Endpoint?.Address, ':', instance?.Endpoint?.Port);

// Modify instance
await rds.send(new ModifyDBInstanceCommand({
  DBInstanceIdentifier: 'mydb',
  AllocatedStorage: 50,
  ApplyImmediately: true,
}));

// Stop instance
await rds.send(new StopDBInstanceCommand({
  DBInstanceIdentifier: 'mydb',
}));

Behavior Notes

RDS in AWSim tracks instance metadata and state transitions only — no actual database engine is started.
Connecting to the Endpoint.Address returned by RDS will fail — it is a placeholder address, not a real database server.
Persistence is enabled: instances, clusters, subnet groups, and parameter groups survive AWSim restarts.
Engine types (mysql, postgres, aurora, etc.) and engine versions are accepted without validation.
Status transitions (creating → available) happen quickly (simulated); real AWS may take several minutes.
MultiAZ instances are tracked but no actual failover or replication occurs.

RDS ​

Configuration ​

Quick Start ​

Operations ​

DB Instances ​

DB Clusters (Aurora) ​

DB Subnet Groups ​

DB Parameter Groups ​

DB Cluster Parameter Groups (Aurora) ​

DB Snapshots ​

DB Cluster Snapshots (Aurora) ​

Engine Versions & Options ​

DB Cluster Endpoints ​

Stubs ​

Tags ​

Curl Examples ​

SDK Example ​

Behavior Notes ​

RDS