Add SQL Server instance scoping configuration page

config/_default/menus/main.en.yaml

@@ -4635,6 +4635,11 @@ menu:
       parent: dbm
       identifier: dbm_setup_architecture
       weight: 2
+    - name: SQL Server Configurations
+      url: database_monitoring/architecture/sql_server/
+      parent: dbm_setup_architecture
+      identifier: dbm_architecture_sql_server
+      weight: 6
     - name: Setting Up Postgres
       url: database_monitoring/setup_postgres/
       parent: dbm

content/en/database_monitoring/architecture/sql_server.md

@@ -0,0 +1,217 @@
+---
+title: SQL Server Configurations
+description: Configure SQL Server instance scoping for Database Monitoring, covering named instances, port-based instances, and database-level options.
+further_reading:
+- link: "/database_monitoring/architecture/"
+  tag: "Documentation"
+  text: "DBM Setup Architectures"
+- link: "/database_monitoring/setup_sql_server/"
+  tag: "Documentation"
+  text: "Setting up SQL Server"
+---
+
+## Overview
+
+Each check instance in the Datadog Agent configuration creates one Database Monitoring (DBM) instance. The [database_identifier](/database_monitoring/guide/database_identifier/) template determines what the Agent considers a distinct DBM instance.
+
+| Key difference | Details |
+|---|---|
+| Host format | `HOST,PORT` (comma, not colon) |
+| Named instances | Use `HOST\INSTANCENAME` with port `0` to trigger SQL Server Browser Service (SSBS) |
+| DBM scope | DMVs (`sys.dm_exec_*`) are instance-wide. There is no `dbstrict` equivalent |
+
+Available template variables: `$resolved_hostname`, `$host`, `$port`, `$azure_name`, `$database`, `$server_name`, `$instance_name`, `$full_server_name` (from `@@SERVERNAME`), plus any key from tags.
+
+**Scenario**: `sql-prod.example.com` with three SQL Server instances:
+
+| Instance | Port | Databases |
+|---|---|---|
+| Default instance | 1433 | AppDB, ReportsDB |
+| Named instance (SQLEXPRESS) | Dynamic (SSBS) | DevDB, TestDB |
+| Secondary instance | 1434 | LegacyDB |
+
+## Option 1: All instances (recommended)
+
+<div class="alert alert-info">Cover every SQL Server instance on the host with one entry each. Use <code>database_autodiscovery: true</code> on each entry so new databases are picked up automatically. <code>$full_server_name</code> is the best identifier because it encodes <code>@@SERVERNAME</code>, naturally distinguishing named instances from the default instance.</div>
+
+One entry per SQL Server instance, including named instances.
+
+Based on the example scenario above, this counts as three DBM instances.
+
+```yaml
+instances:
+  - host: sql-prod.example.com,1433
+    username: datadog
+    password: "<PASSWORD>"
+    dbm: true
+    database_autodiscovery: true
+    database_identifier:
+      template: "$resolved_hostname:$port"
+
+  - host: sql-prod.example.com,1434
+    username: datadog
+    password: "<PASSWORD>"
+    dbm: true
+    database_autodiscovery: true
+    database_identifier:
+      template: "$resolved_hostname:$port"
+
+  - host: "sql-prod.example.com\\SQLEXPRESS,0"  # port 0 triggers SSBS dynamic port discovery
+    username: datadog
+    password: "<PASSWORD>"
+    dbm: true
+    database_autodiscovery: true
+    database_identifier:
+      template: "$full_server_name"  # → "SQL-PROD\SQLEXPRESS"
+```
+
+## Option 2: Instance level (port-based)
+
+<div class="alert alert-info">Use this option when named instances are not present and only port-based instances need coverage.</div>
+
+Covers port-based instances only. Named instances are not included.
+
+Based on the example scenario above, this counts as two DBM instances.
+
+```yaml
+instances:
+  - host: sql-prod.example.com,1433
+    username: datadog
+    password: "<PASSWORD>"
+    dbm: true
+    database_autodiscovery: true
+    database_identifier:
+      template: "$resolved_hostname:$port"  # → "sql-prod.example.com:1433"
+
+  - host: sql-prod.example.com,1434
+    username: datadog
+    password: "<PASSWORD>"
+    dbm: true
+    database_autodiscovery: true
+    database_identifier:
+      template: "$resolved_hostname:$port"  # → "sql-prod.example.com:1434"
+```
+
+## Option 3: Database level
+
+<div class="alert alert-info">Use database-level scoping only if different teams own different databases and need isolated DBM views, or if billing requires per-database cost attribution. DMV data is always instance-wide regardless of the <code>database</code> field.</div>
+
+One entry per database. Set `instance_metrics.enabled: false` to prevent server-level metrics from being duplicated across entries that share the same SQL Server instance.
+
+**Note**: DBM query metrics and samples remain instance-wide. The `database` field narrows the connection context but does not filter DMV data the way Postgres's `dbstrict` does.
+
+Based on the example scenario above, this counts as five DBM instances.
+
+```yaml
+instances:
+  # Default instance (:1433), AppDB
+  - host: sql-prod.example.com
+    username: datadog
+    password: "<PASSWORD>"
+    dbm: true
+    database: AppDB
+    database_identifier:
+      template: "$full_server_name-$database"  # → "SQL-PROD-AppDB"
+    database_metrics:
+      instance_metrics:
+        enabled: false
+
+  # Default instance (:1433), ReportsDB
+  - host: sql-prod.example.com
+    username: datadog
+    password: "<PASSWORD>"
+    dbm: true
+    database: ReportsDB
+    database_identifier:
+      template: "$full_server_name-$database"  # → "SQL-PROD-ReportsDB"
+    database_metrics:
+      instance_metrics:
+        enabled: false
+
+  # :1434 instance, LegacyDB
+  - host: sql-prod.example.com,1434
+    username: datadog
+    password: "<PASSWORD>"
+    dbm: true
+    database: LegacyDB
+    database_identifier:
+      template: "$full_server_name-$database"  # → "SQL-PROD-LegacyDB"
+    database_metrics:
+      instance_metrics:
+        enabled: false
+
+  # SQLEXPRESS, DevDB
+  - host: "sql-prod.example.com\\SQLEXPRESS,0"
+    username: datadog
+    password: "<PASSWORD>"
+    dbm: true
+    database: DevDB
+    database_identifier:
+      template: "$full_server_name-$database"  # → "SQL-PROD\SQLEXPRESS-DevDB"
+    database_metrics:
+      instance_metrics:
+        enabled: false
+
+  # SQLEXPRESS, TestDB
+  - host: "sql-prod.example.com\\SQLEXPRESS,0"
+    username: datadog
+    password: "<PASSWORD>"
+    dbm: true
+    database: TestDB
+    database_identifier:
+      template: "$full_server_name-$database"  # → "SQL-PROD\SQLEXPRESS-TestDB"
+    database_metrics:
+      instance_metrics:
+        enabled: false
+```
+
+## Managed services
+
+### Amazon RDS for SQL Server
+
+```yaml
+instances:
+  - host: mydb.cfxgae8cilcf.us-east-1.rds.amazonaws.com
+    username: datadog
+    password: "<PASSWORD>"
+    dbm: true
+    database_autodiscovery: true
+    aws:
+      instance_endpoint: mydb.cfxgae8cilcf.us-east-1.rds.amazonaws.com
+    database_identifier:
+      template: "$resolved_hostname"
+```
+
+If connecting through RDS Proxy, set `reported_hostname` to the RDS instance endpoint.
+
+### Google Cloud SQL for SQL Server
+
+`reported_hostname` is required when using the Cloud SQL Auth Proxy. Named instances and custom ports are not supported on Cloud SQL.
+
+```yaml
+instances:
+  - host: 127.0.0.1,1433
+    username: datadog
+    password: "<PASSWORD>"
+    dbm: true
+    reported_hostname: my-instance.us-central1.my-project
+    database_autodiscovery: true
+    gcp:
+      project_id: my-project
+      instance_id: my-instance
+    database_identifier:
+      template: "$resolved_hostname"
+```
+
+For Azure SQL Database, Managed Instance, and Elastic Pools, see [Azure SQL Configurations](/database_monitoring/architecture/azure_sql/).
+
+| | RDS SQL Server | Cloud SQL SQL Server | Azure SQL Managed Instance |
+|---|---|---|---|
+| Config block | `aws` | `gcp` | `azure` |
+| Managed auth | IAM (`aws.managed_authentication`) | None | Managed identity (`managed_identity`) |
+| `database_autodiscovery` | Yes | Yes | Yes |
+| Named instances | No | No | Rare |
+| `reported_hostname` needed | If using RDS Proxy | Yes (Auth Proxy) | No |
+| Recommended identifier | `$resolved_hostname` | `$resolved_hostname` (through `reported_hostname`) | `$azure_name` |
+
+{{< partial name="whats-next/whats-next.html" >}}