coder · Emyrk · May 28, 2025 · May 27, 2025 · May 27, 2025 · May 27, 2025
diff --git a/coderd/parameters_test.go b/coderd/parameters_test.go
@@ -15,6 +15,7 @@ import (
 	"github.com/coder/coder/v2/coderd/database/dbtestutil"
 	"github.com/coder/coder/v2/coderd/database/pubsub"
 	"github.com/coder/coder/v2/coderd/rbac"
+	"github.com/coder/coder/v2/coderd/util/ptr"
 	"github.com/coder/coder/v2/codersdk"
 	"github.com/coder/coder/v2/codersdk/wsjson"
 	"github.com/coder/coder/v2/provisioner/echo"
@@ -211,6 +212,86 @@ func TestDynamicParametersWithTerraformValues(t *testing.T) {
 		require.Zero(t, setup.api.FileCache.Count())
 	})
 
+	t.Run("RebuildParameters", func(t *testing.T) {
+		t.Parallel()
+
+		dynamicParametersTerraformSource, err := os.ReadFile("testdata/parameters/modules/main.tf")
+		require.NoError(t, err)
+
+		modulesArchive, err := terraform.GetModulesArchive(os.DirFS("testdata/parameters/modules"))
+		require.NoError(t, err)
+
+		setup := setupDynamicParamsTest(t, setupDynamicParamsTestParams{
+			provisionerDaemonVersion: provProto.CurrentVersion.String(),
+			mainTF:                   dynamicParametersTerraformSource,
+			modulesArchive:           modulesArchive,
+			plan:                     nil,
+			static:                   nil,
+		})
+
+		ctx := testutil.Context(t, testutil.WaitMedium)
+		stream := setup.stream
+		previews := stream.Chan()
+
+		// Should see the output of the module represented
+		preview := testutil.RequireReceive(ctx, t, previews)
+		require.Equal(t, -1, preview.ID)
+		require.Empty(t, preview.Diagnostics)
+
+		require.Len(t, preview.Parameters, 1)
+		require.Equal(t, "jetbrains_ide", preview.Parameters[0].Name)
+		require.True(t, preview.Parameters[0].Value.Valid)
+		require.Equal(t, "CL", preview.Parameters[0].Value.Value)
+		_ = stream.Close(websocket.StatusGoingAway)
+
+		wrk := coderdtest.CreateWorkspace(t, setup.client, setup.template.ID, func(request *codersdk.CreateWorkspaceRequest) {
+			request.RichParameterValues = []codersdk.WorkspaceBuildParameter{
+				{
+					Name:  preview.Parameters[0].Name,
+					Value: "GO",
+				},
+			}
+		})
+		coderdtest.AwaitWorkspaceBuildJobCompleted(t, setup.client, wrk.LatestBuild.ID)
+
+		params, err := setup.client.WorkspaceBuildParameters(ctx, wrk.LatestBuild.ID)
+		require.NoError(t, err)
+		require.Len(t, params, 1)
+		require.Equal(t, "jetbrains_ide", params[0].Name)
+		require.Equal(t, "GO", params[0].Value)
+
+		// A helper function to assert params
+		doTransition := func(t *testing.T, trans codersdk.WorkspaceTransition) {
+			t.Helper()
+
+			fooVal := coderdtest.RandomUsername(t)
+			bld, err := setup.client.CreateWorkspaceBuild(ctx, wrk.ID, codersdk.CreateWorkspaceBuildRequest{
+				TemplateVersionID: setup.template.ActiveVersionID,
+				Transition:        trans,
+				RichParameterValues: []codersdk.WorkspaceBuildParameter{
+					// No validation, so this should work as is.
+					// Overwrite the value on each transition
+					{Name: "foo", Value: fooVal},
+				},
+				EnableDynamicParameters: ptr.Ref(true),
+			})
+			require.NoError(t, err)
+			coderdtest.AwaitWorkspaceBuildJobCompleted(t, setup.client, wrk.LatestBuild.ID)
+
+			latestParams, err := setup.client.WorkspaceBuildParameters(ctx, bld.ID)
+			require.NoError(t, err)
+			require.ElementsMatch(t, latestParams, []codersdk.WorkspaceBuildParameter{
+				{Name: "jetbrains_ide", Value: "GO"},
+				{Name: "foo", Value: fooVal},
+			})
+		}
+
+		// Restart the workspace, then delete. Asserting params on all builds.
+		doTransition(t, codersdk.WorkspaceTransitionStop)
+		doTransition(t, codersdk.WorkspaceTransitionStart)
+		doTransition(t, codersdk.WorkspaceTransitionDelete)
+	})
+
 	t.Run("BadOwner", func(t *testing.T) {
 		t.Parallel()
 
@@ -266,9 +347,10 @@ type setupDynamicParamsTestParams struct {
 }
 
 type dynamicParamsTest struct {
-	client *codersdk.Client
-	api    *coderd.API
-	stream *wsjson.Stream[codersdk.DynamicParametersResponse, codersdk.DynamicParametersRequest]
+	client   *codersdk.Client
+	api      *coderd.API
+	stream   *wsjson.Stream[codersdk.DynamicParametersResponse, codersdk.DynamicParametersRequest]
+	template codersdk.Template
 }
 
 func setupDynamicParamsTest(t *testing.T, args setupDynamicParamsTestParams) dynamicParamsTest {
@@ -300,7 +382,7 @@ func setupDynamicParamsTest(t *testing.T, args setupDynamicParamsTestParams) dyn
 
 	version := coderdtest.CreateTemplateVersion(t, templateAdmin, owner.OrganizationID, files)
 	coderdtest.AwaitTemplateVersionJobCompleted(t, templateAdmin, version.ID)
-	_ = coderdtest.CreateTemplate(t, templateAdmin, owner.OrganizationID, version.ID)
+	tpl := coderdtest.CreateTemplate(t, templateAdmin, owner.OrganizationID, version.ID)
 
 	ctx := testutil.Context(t, testutil.WaitShort)
 	stream, err := templateAdmin.TemplateVersionDynamicParameters(ctx, version.ID)
@@ -321,9 +403,10 @@ func setupDynamicParamsTest(t *testing.T, args setupDynamicParamsTestParams) dyn
 	})
 
 	return dynamicParamsTest{
-		client: ownerClient,
-		stream: stream,
-		api:    api,
+		client:   ownerClient,
+		api:      api,
+		stream:   stream,
+		template: tpl,
 	}
 }
 

diff --git a/coderd/wsbuilder/wsbuilder.go b/coderd/wsbuilder/wsbuilder.go
@@ -623,6 +623,11 @@ func (b *Builder) getParameters() (names, values []string, err error) {
 		return nil, nil, BuildError{http.StatusBadRequest, "Unable to build workspace with unsupported parameters", err}
 	}
 
+	lastBuildParameterValues := db2sdk.WorkspaceBuildParameters(lastBuildParameters)
+	resolver := codersdk.ParameterResolver{
+		Rich: lastBuildParameterValues,
+	}
+
 	// Dynamic parameters skip all parameter validation.
 	// Deleting a workspace also should skip parameter validation.
 	// Pass the user's input as is.
@@ -632,19 +637,34 @@ func (b *Builder) getParameters() (names, values []string, err error) {
 		//  conditional parameter existence, the static frame of reference
 		//  is not sufficient. So assume the user is correct, or pull in the
 		//  dynamic param code to find the actual parameters.
+		latestValues := make(map[string]string, len(b.richParameterValues))
+		for _, latest := range b.richParameterValues {
+			latestValues[latest.Name] = latest.Value
+		}
+
+		// Merge the inputs with values from the previous build.
+		for _, last := range lastBuildParameterValues {
+			// TODO: Ideally we use the resolver here and look at parameter
+			//   fields such as 'ephemeral'. This requires loading the terraform
+			//   files. For now, just send the previous inputs as is.
+			if _, exists := latestValues[last.Name]; exists {
+				// latestValues take priority, so skip this previous value.
+				continue
+			}
+			names = append(names, last.Name)
+			values = append(values, last.Value)
+		}
+
 		for _, value := range b.richParameterValues {
 			names = append(names, value.Name)
 			values = append(values, value.Value)
 		}
+
 		b.parameterNames = &names
 		b.parameterValues = &values
 		return names, values, nil
 	}
 
-	resolver := codersdk.ParameterResolver{
-		Rich: db2sdk.WorkspaceBuildParameters(lastBuildParameters),
-	}
-
 	for _, templateVersionParameter := range templateVersionParameters {
 		tvp, err := db2sdk.TemplateVersionParameter(templateVersionParameter)
 		if err != nil {