MSSQL scaler documentation

Signed-off-by: Chris Gillum <[email protected]>

content/docs/2.2/scalers/mssql.md

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+title = "MSSQL"
+layout = "scaler"
+availability = "v2.2+"
+maintainer = "Microsoft"
+description = "Scale applications based on Microsoft SQL Server (MSSQL) query results."
+go_file = "mssql_scaler"
++++
+
+### Trigger Specification
+
+This specification describes the `mssql` trigger that scales based on the results of a [Microsoft SQL Server](https://www.microsoft.com/sql-server/) (MSSQL) query result.
+
+The `mssql` trigger always requires the following information:
+
+- `query` - a [T-SQL](https://docs.microsoft.com/sql/t-sql/language-reference) query that returns a single numeric value. This can be a regular query or the name of a stored procedure.
+- `targetValue` - a threshold that is used as `targetAverageValue` in the Horizontal Pod Autoscaler (HPA).
+
+To connect to the MSSQL instance you can provide either:
+
+- `connectionStringFromEnv` - The name of an environment variable containing a valid MSSQL connection string.
+
+Or provide more detailed information:
+
+- `host` - The hostname of the MSSQL instance endpoint.
+- `port` - The port number of the MSSQL instance endpoint.
+- `database` - The name of the database to query.
+- `username` - The username credential for connecting to the MSSQL instance.
+- `passwordFromEnv` - The name of an environment variable containing the password credential for connecting to the MSSQL instance.
+
+Connection string values can be either in a URL format (note the URL encoding of special characters):
+
+```
+sqlserver://user1:Password%[email protected]:1433?database=AdventureWorks
+```
+
+Or in a more traditional OLE DB format:
+
+```
+Server=example.database.windows.net;port=1433;Database=AdventureWorks;Persist Security Info=False;User ID=user1;Password=Password#1;MultipleActiveResultSets=False;Encrypt=True;TrustServerCertificate=False;Connection Timeout=30;
+```
+
+Furthermore, you can optionally assign a name to the metric using the `metricName` value. If not specified, the `metricName` will be generated automatically based on the `database` value (if specified), or the `host` value, or will be in the form `mssql-{sha256hash}` where `{sha256hash}` is a SHA-256 hash of the connection string.
+
+The following is an example that uses a connection string to connect to an Azure SQL instance:
+
+```yaml
+triggers:
+- type: mssql
+  metadata:
+    connectionFromEnv: MSSQL_CONNECTION_STRING
+    query: "SELECT CEILING(COUNT(*) / 16.0) FROM task_instance WHERE state='running' OR state='queued'"
+    targetValue: 1
+    metricName: backlog_process_count # optional - the generated value would be `mssql-{sha256hash}`
+```
+
+Alternatively, the following example explicitly specifies the connection information:
+
+```yaml
+triggers:
+- type: mssql
+  metadata:
+    userName: "kedaUser"
+    passwordFromEnv: MSSQL_PASSWORD
+    host: mssql-instance.namespace.cluster.local
+    port: "1433" # optional
+    database: test_db_name
+    query: "SELECT CEILING(COUNT(*) / 16.0) FROM task_instance WHERE state='running' OR state='queued'"
+    targetValue: 1
+    metricName: backlog_process_count # optional - the generated value would be `mssql-test_db_name`
+```
+
+### Authentication parameters
+
+You can authenticate with the MSSQL instance using connection string or password authentication.
+
+**Connection string authentication:**
+
+- `connectionString` - The connection string for the MSSQL instance.
+
+**Password authentication:**
+
+- `password` - The password credential for connecting to the MSSQL instance.
+
+### Example
+
+The following is an example of how to deploy a scaled object with the `mssql` scale trigger that uses `TriggerAuthentication`.
+
+```yaml
+apiVersion: v1
+kind: Secret
+metadata:
+  name: mssql-secrets
+  namespace: my-project
+type: Opaque
+data:
+  mssql_conn_str: "Server=example.database.windows.net;port=1433;Database=AdventureWorks;Persist Security Info=False;User ID=user1;Password=Password#1;Encrypt=True;TrustServerCertificate=False;"
+---
+apiVersion: keda.sh/v1alpha1
+kind: TriggerAuthentication
+metadata:
+  name: keda-trigger-auth-mssql-secret
+  namespace: my-project
+spec:
+  secretTargetRef:
+  - parameter: connectionString
+    name: mssql-secrets
+    key: mssql_conn_str
+---
+apiVersion: keda.sh/v1alpha1
+kind: ScaledObject
+metadata:
+  name: mssql-scaledobject
+  namespace: my-project
+spec:
+  scaleTargetRef:
+    name: worker
+  triggers:
+  - type: mssql
+    metadata:
+      targetValue: 1
+      query: "SELECT CEILING(COUNT(*) / 16.0) FROM task_instance WHERE state='running' OR state='queued'"
+    authenticationRef:
+      name: keda-trigger-auth-mssql-secret
+```