RDS

Overview

CloudMock emulates Amazon RDS management operations, supporting DB instance, cluster, snapshot, and subnet group lifecycle. Instances are metadata-only records — no database engine is started.

Supported Operations

Operation	Status	Notes
CreateDBInstance	Supported	Creates a DB instance record
DeleteDBInstance	Supported	Deletes a DB instance
DescribeDBInstances	Supported	Returns all DB instances
ModifyDBInstance	Supported	Updates instance attributes
CreateDBCluster	Supported	Creates an Aurora cluster
DeleteDBCluster	Supported	Deletes a cluster
DescribeDBClusters	Supported	Returns all clusters
CreateDBSnapshot	Supported	Creates a snapshot of a DB instance
DeleteDBSnapshot	Supported	Deletes a snapshot
DescribeDBSnapshots	Supported	Returns all snapshots
CreateDBSubnetGroup	Supported	Creates a subnet group
DescribeDBSubnetGroups	Supported	Returns all subnet groups
DeleteDBSubnetGroup	Supported	Deletes a subnet group
AddTagsToResource	Supported	Adds tags to a resource
RemoveTagsFromResource	Supported	Removes tags
ListTagsForResource	Supported	Returns tags for a resource

Quick Start

curl

# Create a DB instance
curl -X POST "http://localhost:4566/?Action=CreateDBInstance&DBInstanceIdentifier=my-db&DBInstanceClass=db.t3.micro&Engine=mysql&MasterUsername=admin&MasterUserPassword=Password123&AllocatedStorage=20"

# Describe instances
curl -X POST "http://localhost:4566/?Action=DescribeDBInstances"

Node.js

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

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

await rds.send(new CreateDBInstanceCommand({
  DBInstanceIdentifier: 'test-db',
  DBInstanceClass: 'db.t3.micro',
  Engine: 'postgres',
  MasterUsername: 'postgres',
  MasterUserPassword: 'postgres123',
  AllocatedStorage: 20,
}));

const { DBInstances } = await rds.send(new DescribeDBInstancesCommand({}));
DBInstances?.forEach(db => console.log(db.DBInstanceIdentifier, db.DBInstanceStatus));

Python

import boto3

rds = boto3.client('rds', endpoint_url='http://localhost:4566',
                   aws_access_key_id='test', aws_secret_access_key='test',
                   region_name='us-east-1')

rds.create_db_instance(
    DBInstanceIdentifier='test-db',
    DBInstanceClass='db.t3.micro',
    Engine='postgres',
    MasterUsername='postgres',
    MasterUserPassword='postgres123',
    AllocatedStorage=20,
)

response = rds.describe_db_instances()
for db in response['DBInstances']:
    print(db['DBInstanceIdentifier'], db['DBInstanceStatus'])

Configuration

cloudmock.yml

services:
  rds:
    enabled: true

No additional service-specific configuration is required.

Known Differences from AWS

• DB instances are metadata-only records. No actual database engine is started.
• Connection strings and endpoints returned in DescribeDBInstances are synthetic and not connectable.
• Parameter groups, option groups, and enhanced monitoring are accepted but not enforced.
• Aurora serverless v2, Proxy, and Blue/Green deployments are not implemented.
• Instance status immediately transitions to available after creation.

Error Codes

Code	HTTP Status	Description
DBInstanceNotFound	404	The specified DB instance does not exist
DBInstanceAlreadyExists	400	A DB instance with this identifier already exists
DBSnapshotNotFound	404	The specified snapshot does not exist
InvalidDBInstanceState	400	The DB instance is not in a valid state for this operation