[stress testing] Allow default matrix selection override (#9249)

eng/common/scripts/stress-testing/find-all-stress-packages.ps1

@@ -48,11 +48,21 @@ function FindStressPackages(
 
         VerifyAddonsVersion $chart $chartFile
 
+        # Default to "sparse" matrix selection type, unless a default is specified
+        # in Chart.yaml annotations, or an override is passed in from the command line
+        $selection = if ($MatrixSelection) {
+            $MatrixSelection
+        } elseif ($chart['annotations'] -and $chart['annotations']['matrixSelection']) {
+            $chart['annotations']['matrixSelection']
+        } else {
+            "sparse"
+        }
+
         $matrixFilePath = (Join-Path $chartFile.Directory.FullName $MatrixFileName)
         if (Test-Path $matrixFilePath) {
             GenerateScenarioMatrix `
                 -matrixFilePath $matrixFilePath `
-                -Selection $MatrixSelection `
+                -Selection $selection `
                 -DisplayNameFilter $MatrixDisplayNameFilter `
                 -Filters $MatrixFilters `
                 -Replace $MatrixReplace `

eng/common/scripts/stress-testing/stress-test-deployment-lib.ps1

@@ -103,7 +103,7 @@ function DeployStressTests(
     [Parameter(Mandatory=$False)][switch]$Template,
     [Parameter(Mandatory=$False)][switch]$RetryFailedTests,
     [Parameter(Mandatory=$False)][string]$MatrixFileName,
-    [Parameter(Mandatory=$False)][string]$MatrixSelection = "sparse",
+    [Parameter(Mandatory=$False)][string]$MatrixSelection,
     [Parameter(Mandatory=$False)][string]$MatrixDisplayNameFilter,
     [Parameter(Mandatory=$False)][array]$MatrixFilters,
     [Parameter(Mandatory=$False)][array]$MatrixReplace,

tools/stress-cluster/chaos/README.md

@@ -624,6 +624,17 @@ A more detailed information on the logic behind the matrix generation can be fou
 
 The `stress-test-addons` helm library will handle a scenarios matrix automatically, and deploy multiple instances of the stress test job, one for each scenario with customized values.
 
+NOTE: Matrix generation has two modes, 'sparse' and 'all', which generate either the minimum set of tests covering all parameters or an exhaustive set. See https://github.com/Azure/azure-sdk-tools/blob/main/doc/common/matrix_generator.md#matrix-generation-behavior for more details. The deploy script defaults to 'sparse' mode, but this can be customized either by passing `-MatrixSelection <mode>` to the deploy script or overriding the default selection via `annotations.matrixSelection` under Chart.yaml:
+
+```
+# Chart.yaml
+...
+annotations:
+  stressTest: 'true'
+  namespace: 'examples'
+  matrixSelection: 'all'
+```
+
 ### Node Size Requirements
 
 The stress test cluster may be deployed with several node SKUs (see [agentPoolProfiles declaration and