Add MySQL instance scoping configuration page

config/_default/menus/main.en.yaml

@@ -4635,6 +4635,11 @@ menu:
       parent: dbm
       identifier: dbm_setup_architecture
       weight: 2
+    - name: MySQL Configurations
+      url: database_monitoring/architecture/mysql/
+      parent: dbm_setup_architecture
+      identifier: dbm_architecture_mysql
+      weight: 3
     - name: Setting Up Postgres
       url: database_monitoring/setup_postgres/
       parent: dbm

content/en/database_monitoring/architecture/mysql.md

@@ -0,0 +1,143 @@
+---
+title: MySQL Configurations
+description: Configure MySQL instance scoping for Database Monitoring across self-hosted, RDS, Aurora, Cloud SQL, and Azure managed services.
+further_reading:
+- link: "/database_monitoring/architecture/"
+  tag: "Documentation"
+  text: "DBM Setup Architectures"
+- link: "/database_monitoring/setup_mysql/"
+  tag: "Documentation"
+  text: "Setting up MySQL"
+---
+
+## 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.
+
+MySQL DBM data comes from `performance_schema`, which is instance-wide. There is no `dbstrict` equivalent. DBM query metrics and samples always cover all schemas on an instance regardless of configuration.
+
+Available template variables: `$resolved_hostname`, `$host`, `$port`, `$mysql_sock`, plus any key from tags.
+
+**Scenario**: `mysql-prod.example.com` with two MySQL instances:
+
+| Instance | Port | Schemas |
+|---|---|---|
+| Production | 3306 | app, users, orders |
+| Reporting | 3307 | reports, archive |
+
+## Instance level
+
+<div class="alert alert-info">Use one entry per MySQL process (<code>$resolved_hostname:$port</code>). <code>performance_schema</code> is instance-wide. Database-level scoping is not supported.</div>
+
+One entry per MySQL instance, with port included in the identifier.
+
+Based on the example scenario above, this counts as two DBM instances.
+
+```yaml
+instances:
+  - host: mysql-prod.example.com
+    port: 3306
+    username: datadog
+    password: "<PASSWORD>"
+    dbm: true
+    database_identifier:
+      template: "$resolved_hostname:$port"  # → "mysql-prod.example.com:3306"
+
+  - host: mysql-prod.example.com
+    port: 3307
+    username: datadog
+    password: "<PASSWORD>"
+    dbm: true
+    database_identifier:
+      template: "$resolved_hostname:$port"  # → "mysql-prod.example.com:3307"
+```
+
+## Managed services
+
+### Amazon Aurora (MySQL-compatible)
+
+Use one entry per Aurora instance (writer + each reader). Never use the cluster or reader endpoint. The check logs a warning when `SHOW ENGINE INNODB STATUS` returns no data on Aurora reader instances. InnoDB metrics are not available on Aurora readers.
+
+```yaml
+instances:
+  # Writer instance
+  - host: mydb-instance-1.cfxgae8cilcf.us-east-1.rds.amazonaws.com
+    port: 3306
+    username: datadog
+    password: "<PASSWORD>"
+    dbm: true
+    aws:
+      instance_endpoint: mydb-instance-1.cfxgae8cilcf.us-east-1.rds.amazonaws.com
+    database_identifier:
+      template: "$resolved_hostname:$port"
+
+  # Reader instance
+  - host: mydb-instance-2.cfxgae8cilcf.us-east-1.rds.amazonaws.com
+    port: 3306
+    username: datadog
+    password: "<PASSWORD>"
+    dbm: true
+    aws:
+      instance_endpoint: mydb-instance-2.cfxgae8cilcf.us-east-1.rds.amazonaws.com
+    database_identifier:
+      template: "$resolved_hostname:$port"
+```
+
+### Amazon RDS for MySQL
+
+One entry per RDS instance.
+
+```yaml
+instances:
+  - host: mydb.cfxgae8cilcf.us-east-1.rds.amazonaws.com
+    port: 3306
+    username: datadog
+    password: "<PASSWORD>"
+    dbm: true
+    aws:
+      instance_endpoint: mydb.cfxgae8cilcf.us-east-1.rds.amazonaws.com
+      region: us-east-1
+      managed_authentication:
+        enabled: true
+    database_identifier:
+      template: "$resolved_hostname:$port"
+```
+
+### Azure Database for MySQL (Flexible Server)
+
+Single Server is deprecated by Microsoft. Use Flexible Server only.
+
+```yaml
+instances:
+  - host: myserver.mysql.database.azure.com
+    port: 3306
+    username: datadog
+    password: "<PASSWORD>"
+    dbm: true
+    azure:
+      deployment_type: flexible_server
+      fully_qualified_domain_name: myserver.mysql.database.azure.com
+    database_identifier:
+      template: "$resolved_hostname:$port"
+```
+
+### Google Cloud SQL for MySQL
+
+`reported_hostname` is required when using the Cloud SQL Auth Proxy.
+
+```yaml
+instances:
+  - host: 127.0.0.1
+    port: 3306
+    username: datadog
+    password: "<PASSWORD>"
+    dbm: true
+    reported_hostname: my-instance.us-central1.my-project
+    gcp:
+      project_id: my-project
+      instance_id: my-instance
+    database_identifier:
+      template: "$resolved_hostname:$port"
+```
+
+{{< partial name="whats-next/whats-next.html" >}}