feat: add --username-infix to scaletest create-users (#28514)

cli/exp_scaletest_createusers.go

@@ -23,6 +23,7 @@ func (r *RootCmd) scaletestCreateUsers() *serpent.Command {
 	var (
 		count                   int64
 		templateAdminPercentage float64
+		usernameInfix           string
 		noCleanup               bool
 
 		tracingFlags    = &scaletestTracingFlags{}
@@ -93,6 +94,15 @@ func (r *RootCmd) scaletestCreateUsers() *serpent.Command {
 
 			th := harness.NewTestHarness(strategy.toStrategy(), cleanupStrategy.toStrategy())
 
+			// The scaletest- root is always kept so the cleanup command still
+			// finds these users; --username-infix is inserted between it and the
+			// random suffix, e.g. --username-infix asdf produces usernames like
+			// scaletest-asdf-<random>-<id>.
+			userPrefix := loadtestutil.ScaleTestPrefix + "-"
+			if usernameInfix != "" {
+				userPrefix += usernameInfix + "-"
+			}
+
 			_, _ = fmt.Fprintln(inv.Stderr, "Creating users...")
 			for i := range count {
 				id := strconv.FormatInt(i, 10)
@@ -110,9 +120,15 @@ func (r *RootCmd) scaletestCreateUsers() *serpent.Command {
 					return xerrors.Errorf("create runner client: %w", err)
 				}
 
-				// Username and email are generated by createusers when left empty.
+				username, email, err := loadtestutil.GenerateUserIdentifierWithPrefix(userPrefix, id)
+				if err != nil {
+					return xerrors.Errorf("generate user identifier: %w", err)
+				}
+
 				config := createusers.Config{
 					OrganizationID: me.OrganizationIDs[0],
+					Username:       username,
+					Email:          email,
 				}
 				if err := config.Validate(); err != nil {
 					return xerrors.Errorf("validate config: %w", err)
@@ -191,6 +207,12 @@ func (r *RootCmd) scaletestCreateUsers() *serpent.Command {
 			Description: "Percentage of users to assign the Template Admin role to (0-100).",
 			Value:       serpent.Float64Of(&templateAdminPercentage),
 		},
+		{
+			Flag:        "username-infix",
+			Env:         "CODER_SCALETEST_CREATE_USERS_USERNAME_INFIX",
+			Description: "Optional infix inserted between the mandatory \"scaletest-\" root and the rest of each generated username. For example --username-infix asdf produces usernames like scaletest-asdf-<random>-<id>; leave empty for the default scaletest-<random>-<id> names. Use it to partition users into disjoint pools that a matching --reuse-users run can select. The scaletest- root is always kept so the cleanup command still discovers the users.",
+			Value:       serpent.StringOf(&usernameInfix),
+		},
 		{
 			Flag:        "no-cleanup",
 			Env:         "CODER_SCALETEST_NO_CLEANUP",