/rds-sqlserver

name: rds-sqlserver
version: 1
description: Provides connectivity, authentication, and troubleshooting guidance for Amazon RDS for SQL Server. Applicable when users ask about SSMS times out connecting from EC2, Cannot generate SSPI context with Windows auth, connect RDS SQL Server from Lambda with pymssql, auth_scheme shows NTLM instead of KERBEROS on ECS Fargate, SSM tunnel to RDS SQL Server from laptop, port 1433 security group, TrustServerCertificate=True for localhost tunnels, SPN MSSQLSvc, AWS Managed Microsoft AD, CNAME not RDS endpoint for Kerberos, tds_version='7.4', encryption='require', port-as-string for pymssql, Secrets Manager credential caching in Lambda, error 18456 login failed. Covers Python (pymssql, pyodbc), .NET (Microsoft.Data.SqlClient), Java (JDBC mssql-jdbc), Node.js (tedious), IAM auth via RDS Proxy, and VPC/ECS/EKS/Lambda deployment.

Amazon RDS for SQL Server

Safety guidance

This skill covers creating and modifying RDS for SQL Server resources when the user requests it. The agent MUST confirm the action with the user before executing. Do NOT execute any create or modify operation without explicit user confirmation (e.g., "yes", "proceed", "confirmed", "go ahead"). If the user has not confirmed, present the planned action and ask for approval.

Execute these operations (after user confirmation)

• Create an instance: `create-db-instance` (requires a DB subnet group; RDS SQL Server is VPC-only and not publicly accessible by default)
• Create a custom parameter group: `create-db-parameter-group` (family `sqlserver-ex-15.00`, `sqlserver-se-15.00`, etc.) — needed to set `rds.force_ssl=1` among others
• Create an option group: `create-option-group` (for TDE, S3 integration, SQLServer Audit, Native Backup/Restore, SSIS, SSAS, SSRS)
• Create an RDS Proxy: `create-db-proxy`, `register-db-proxy-targets` (for IAM DB auth in front of SQL Server — see the rds-proxy reference)
• Create an AWS Managed Microsoft AD directory for Windows auth: `create-directory` (then associate via `modify-db-instance --domain`)
• Create a Secrets Manager secret with rotation: `create-secret`, `rotate-secret --rotation-rules AutomaticallyAfterDays=N`
• Change backup retention, deletion protection, log exports: `modify-db-instance --backup-retention-period` / `--deletion-protection` / `--cloudwatch-logs-export-configuration`
• Attach/detach parameter group or option group: `modify-db-instance --db-parameter-group-name / --option-group-name`
• Tag resources: `add-tags-to-resource`, `remove-tags-from-resource`

Resource tagging (always apply on resource creation)

When creating any RDS for SQL Server resource (`create-db-instance`, `create-db-parameter-group`, `create-option-group`, `create-db-proxy`, `create-secret` for RDS credentials, `create-directory` for Windows auth), ALWAYS include these tags using the RDS list-of-records `--tags` syntax (AWS Directory Service and Secrets Manager use the same shape):

`--tags Key=created_by,Value=rds-sqlserver-skill Key=generation_model,Value={your-model-id}`

Example: `--tags Key=created_by,Value=rds-sqlserver-skill Key=generation_model,Value=claude-sonnet-4-20250514`

Include these tags even if the user does not mention tagging, so that they can identify the resources created via this skill. If the user provides additional tags, append these to their tags rather than replacing them. The same applies when tagging via `add-tags-to-resource` on existing resources.

Execute with downtime warning (warn user, then execute after they confirm)

• Change instance class: `modify-db-instance --db-instance-class` — warn: "This causes a failover in Multi-AZ configurations and brief unavailability on single-AZ instances."
• Minor engine version upgrade: `modify-db-instance --engine-version` within the same major (e.g., 15.00.4X → 15.00.4Y) — warn: "This triggers a restart and may cause a brief outage."
• Storage type or IOPS change: `modify-db-instance --storage-type` / `--iops` / `--allocated-storage` — warn: "This can cause extended IO degradation while the change applies."
• Apply immediately: any `modify-db-instance --apply-immediately` — warn: "This applies outside the maintenance window and may cause downtime now."
• Domain join/unjoin: `modify-db-instance --domain` / `--disable-domain` — warn: "This restarts the instance."

Do NOT execute (refuse, explain why, offer assessment instead)

• Delete instance: `delete-db-instance` — irreversible data loss
• Delete automated backups: `delete-db-instance --delete-automated-backups` — destroys point-in-time recovery history
• Failover: `reboot-db-instance --force-failover` — production impact
• Major version upgrade: `modify-db-instance --engine-version` across major versions (e.g., 15.0 → 16.0) — requires prechecks and a rollback plan; should go through change-control
• Reboot: `reboot-db-instance` — production impact
• Enable public accessibility: `modify-db-instance --publicly-accessible true` — security regression; use SSM port forwarding, VPN, or Direct Connect

When refusing, explain why and offer the matching assessment workflow: > "I can't perform [action] because [reason]. I can run an assessment to help you decide. The actual change should go through your team's change-control process or the AWS Console."

Overview

Amazon RDS for SQL Server is the managed SQL Server service from AWS. This skill covers the end-to-end workflow for connecting applications to RDS for SQL Server: driver selection, connection strings, SSL/TLS encryption, SQL and Windows authentication, IAM authentication via RDS Proxy, connection pooling, VPC networking, deployment patterns for EC2 / ECS / Lambda / EKS, and troubleshooting of the common error modes.

This skill works with the AWS CLI directly. The AWS MCP server is recommended but not required — it adds sandboxed execution, CloudTrail audit, and observability when available.

Common Tasks

1. Verify Dependencies

Check for required tools an