Make App Lock timeout configurable (#982)

[thecrockster]

Add configurable AppLockTimeoutMs setting for the SQL trigger binding's application lock timeout. Previously hardcoded to 30 seconds, the timeout can now be configured via:

• Sql_Trigger_AppLockTimeoutMs app setting
• AppLockTimeoutMs property in host.json SqlOptions

The default remains 30000ms (30 seconds) with a minimum of 1000ms (1 second).

Changes:

• Convert static AppLockStatements field to GetAppLockStatements(int) method
• Add AppLockTimeoutMs property to SqlOptions with validation
• Read config from app settings with SqlOptions fallback in SqlTableChangeMonitor, SqlTriggerListener, and SqlScalerProvider
• Pass appLockTimeoutMs through ScaleMonitor/TargetScaler/MetricsProvider chain
• Add telemetry for HasConfiguredAppLockTimeout and AppLockTimeoutMs
• Add unit tests for new config and GetAppLockStatements method
• Update documentation in BindingsOverview.md and TriggerBinding.md

Closes #982

Description

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why it's being changed, and any links to relevant issues. If this is closing an existing issue use one of the issue linking keywords to link the issue to this PR and have it automatically close when completed.

In addition, go through the checklist below and check each item as you validate it is either handled or not applicable to this change.

Code Changes

• Unit tests are added, if possible
• Integration tests are added if the change is modifying existing behavior of one or more of the bindings
• New or changed code follows the C# style guidelines defined in .editorconfig
• All changes MUST be backwards compatible and changes to the shared az_func.GlobalState table must be compatible with all prior versions of the extension
• Use the ILogger instance to log relevant information, especially information useful for debugging or troubleshooting
• Use async and await for all long-running operations
• Ensure proper usage and propagation of CancellationToken
• T-SQL is safe from SQL Injection attacks through the use of SqlParameters and proper escaping/sanitization of input

Dependencies

• If updating dependencies, run dotnet restore --force-evaluate to update the lock files and ensure that there are NO major versions updates in either src/packages.lock.json or Worker.Extensions.Sql/src/packages.lock.json. If there are, contact the dev team for instructions.

Documentation

• Add samples if the change is modifying or adding functionality
• Update relevant documentation in the docs

[Copilot]

Pull request overview

This pull request adds configurable AppLockTimeoutMs setting for SQL trigger bindings to allow users to adjust the application lock timeout based on their specific server resource conditions. Previously hardcoded at 30 seconds, the timeout can now be configured via app settings (Sql_Trigger_AppLockTimeoutMs) or host.json (AppLockTimeoutMs in SqlOptions), with the same 30-second default and a validated minimum of 1 second.

Changes:

• Converted static AppLockStatements field to GetAppLockStatements(int) method to accept dynamic timeout values
• Added AppLockTimeoutMs property to SqlOptions with validation logic ensuring values are >= 1000ms
• Updated SQL trigger components (SqlTableChangeMonitor, SqlTriggerListener, SqlScalerProvider, and metrics/scaling classes) to read configuration and pass the timeout through the call chain
• Added telemetry tracking for HasConfiguredAppLockTimeout and AppLockTimeoutMs metrics
• Updated documentation to explain the new configuration option

Reviewed changes

Copilot reviewed 15 out of 15 changed files in this pull request and generated 4 comments.

Show a summary per file

File	Description
src/Common/SqlOptions.cs	Added AppLockTimeoutMs property with validation (min 1000ms, default 30000ms)
src/TriggerBinding/SqlTriggerConstants.cs	Converted AppLockStatements static field to GetAppLockStatements(int) method
src/TriggerBinding/SqlTableChangeMonitor.cs	Added config reading and telemetry for app lock timeout
src/TriggerBinding/SqlTriggerListener.cs	Added config reading and app lock statements generation with configured timeout
src/TriggerBinding/SqlTriggerMetricsProvider.cs	Added appLockTimeoutMs parameter and field to store generated statements
src/TriggerBinding/SqlTriggerScaleMonitor.cs	Added appLockTimeoutMs parameter passed to metrics provider
src/TriggerBinding/SqlTriggerTargetScaler.cs	Added appLockTimeoutMs parameter passed to metrics provider
src/TriggerBinding/SqlScalerProvider.cs	Added config reading and validation for app lock timeout
src/Telemetry/Telemetry.cs	Added HasConfiguredAppLockTimeout property and AppLockTimeoutMs measure
test/Unit/SqlOptionsTests.cs	Added tests for AppLockTimeoutMs property validation and JSON serialization
test/Unit/TriggerBinding/SqlTriggerConstantsTests.cs	Added tests for GetAppLockStatements method
test/Unit/TriggerBinding/SqlTriggerScaleMonitorTests.cs	Updated test helpers to pass default app lock timeout
test/Integration/SqlTriggerBindingIntegrationTests.cs	Updated metrics provider instantiation with timeout parameter
docs/TriggerBinding.md	Updated documentation to mention configurable timeout
docs/BindingsOverview.md	Added section documenting Sql_Trigger_AppLockTimeoutMs setting

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[thecrockster]

@Charles-Gagnon @VasuBhog thanks for reviewing. I've applied those changes