all: Add ValidateActionConfig RPC implementation to mux servers

go.mod

@@ -6,7 +6,7 @@ toolchain go1.23.7
 
 require (
 	github.com/google/go-cmp v0.7.0
-	github.com/hashicorp/terraform-plugin-go v0.29.0-alpha.1.0.20250709165734-a8477a15f806
+	github.com/hashicorp/terraform-plugin-go v0.29.0-alpha.1.0.20250717133739-e33a5336fb19
 	github.com/hashicorp/terraform-plugin-log v0.9.0
 	google.golang.org/grpc v1.73.0
 )

go.sum

@@ -21,8 +21,8 @@ github.com/hashicorp/go-plugin v1.6.3 h1:xgHB+ZUSYeuJi96WtxEjzi23uh7YQpznjGh0U0U
 github.com/hashicorp/go-plugin v1.6.3/go.mod h1:MRobyh+Wc/nYy1V4KAXUiYfzxoYhs7V1mlH1Z7iY2h0=
 github.com/hashicorp/go-uuid v1.0.3 h1:2gKiV6YVmrJ1i2CKKa9obLvRieoRGviZFL26PcT/Co8=
 github.com/hashicorp/go-uuid v1.0.3/go.mod h1:6SBZvOh/SIDV7/2o3Jml5SYk/TvGqwFJ/bN7x4byOro=
-github.com/hashicorp/terraform-plugin-go v0.29.0-alpha.1.0.20250709165734-a8477a15f806 h1:i3kA1sT/Fk8Ex+VVKdjf9sFOPwS7w3Q73pfbnxKwdjg=
-github.com/hashicorp/terraform-plugin-go v0.29.0-alpha.1.0.20250709165734-a8477a15f806/go.mod h1:hL//wLEfYo0YVt0TC/VLzia/ADQQto3HEm4/jX2gkdY=
+github.com/hashicorp/terraform-plugin-go v0.29.0-alpha.1.0.20250717133739-e33a5336fb19 h1:P/ZVGEGXt9xSiLz+CrP/JzV2V8rtlE7994AX4jzcGB8=
+github.com/hashicorp/terraform-plugin-go v0.29.0-alpha.1.0.20250717133739-e33a5336fb19/go.mod h1:hL//wLEfYo0YVt0TC/VLzia/ADQQto3HEm4/jX2gkdY=
 github.com/hashicorp/terraform-plugin-log v0.9.0 h1:i7hOA+vdAItN1/7UrfBqBwvYPQ9TFvymaRGZED3FCV0=
 github.com/hashicorp/terraform-plugin-log v0.9.0/go.mod h1:rKL8egZQ/eXSyDqzLUuwUYLVdlYeamldAHSxjUFADow=
 github.com/hashicorp/terraform-registry-address v0.3.0 h1:HMpK3nqaGFPS9VmgRXrJL/dzHNdheGVKk5k7VlFxzCo=

internal/tf5testserver/tf5testserver.go

@@ -69,6 +69,8 @@ type TestServer struct {
 
 	ListResourceCalled map[string]bool
 
+	ValidateActionConfigCalled map[string]bool
+
 	PlanActionCalled map[string]bool
 
 	InvokeActionCalled map[string]bool
@@ -300,6 +302,15 @@ func (s *TestServer) ListResource(_ context.Context, req *tfprotov5.ListResource
 	return nil, nil
 }
 
+func (s *TestServer) ValidateActionConfig(_ context.Context, req *tfprotov5.ValidateActionConfigRequest) (*tfprotov5.ValidateActionConfigResponse, error) {
+	if s.ValidateActionConfigCalled == nil {
+		s.ValidateActionConfigCalled = make(map[string]bool)
+	}
+
+	s.ValidateActionConfigCalled[req.ActionType] = true
+	return nil, nil
+}
+
 func (s *TestServer) PlanAction(ctx context.Context, req *tfprotov5.PlanActionRequest) (*tfprotov5.PlanActionResponse, error) {
 	if s.PlanActionCalled == nil {
 		s.PlanActionCalled = make(map[string]bool)

internal/tf6testserver/tf6testserver.go

@@ -69,6 +69,8 @@ type TestServer struct {
 
 	ListResourceCalled map[string]bool
 
+	ValidateActionConfigCalled map[string]bool
+
 	PlanActionCalled map[string]bool
 
 	InvokeActionCalled map[string]bool
@@ -300,6 +302,15 @@ func (s *TestServer) ListResource(_ context.Context, req *tfprotov6.ListResource
 	return nil, nil
 }
 
+func (s *TestServer) ValidateActionConfig(_ context.Context, req *tfprotov6.ValidateActionConfigRequest) (*tfprotov6.ValidateActionConfigResponse, error) {
+	if s.ValidateActionConfigCalled == nil {
+		s.ValidateActionConfigCalled = make(map[string]bool)
+	}
+
+	s.ValidateActionConfigCalled[req.ActionType] = true
+	return nil, nil
+}
+
 func (s *TestServer) PlanAction(ctx context.Context, req *tfprotov6.PlanActionRequest) (*tfprotov6.PlanActionResponse, error) {
 	if s.PlanActionCalled == nil {
 		s.PlanActionCalled = make(map[string]bool)

internal/tfprotov5tov6/tfprotov5tov6.go

@@ -1126,6 +1126,27 @@ func LinkedResourceSchema(in *tfprotov5.LinkedResourceSchema) *tfprotov6.LinkedR
 	}
 }
 
+func ValidateActionConfigRequest(in *tfprotov5.ValidateActionConfigRequest) *tfprotov6.ValidateActionConfigRequest {
+	if in == nil {
+		return nil
+	}
+
+	return &tfprotov6.ValidateActionConfigRequest{
+		Config:     DynamicValue(in.Config),
+		ActionType: in.ActionType,
+	}
+}
+
+func ValidateActionConfigResponse(in *tfprotov5.ValidateActionConfigResponse) *tfprotov6.ValidateActionConfigResponse {
+	if in == nil {
+		return nil
+	}
+
+	return &tfprotov6.ValidateActionConfigResponse{
+		Diagnostics: Diagnostics(in.Diagnostics),
+	}
+}
+
 func PlanActionRequest(in *tfprotov5.PlanActionRequest) *tfprotov6.PlanActionRequest {
 	if in == nil {
 		return nil

internal/tfprotov5tov6/tfprotov5tov6_test.go

@@ -3243,6 +3243,78 @@ func TestActionSchema(t *testing.T) {
 	}
 }
 
+func TestValidateActionConfigRequest(t *testing.T) {
+	t.Parallel()
+
+	testCases := map[string]struct {
+		in       *tfprotov5.ValidateActionConfigRequest
+		expected *tfprotov6.ValidateActionConfigRequest
+	}{
+		"nil": {
+			in:       nil,
+			expected: nil,
+		},
+		"all-valid-fields": {
+			in: &tfprotov5.ValidateActionConfigRequest{
+				Config:     &testTfprotov5DynamicValue,
+				ActionType: "test_action",
+			},
+			expected: &tfprotov6.ValidateActionConfigRequest{
+				Config:     &testTfprotov6DynamicValue,
+				ActionType: "test_action",
+			},
+		},
+	}
+
+	for name, testCase := range testCases {
+
+		t.Run(name, func(t *testing.T) {
+			t.Parallel()
+
+			got := tfprotov5tov6.ValidateActionConfigRequest(testCase.in)
+
+			if diff := cmp.Diff(got, testCase.expected); diff != "" {
+				t.Errorf("unexpected difference: %s", diff)
+			}
+		})
+	}
+}
+
+func TestValidateActionConfigResponse(t *testing.T) {
+	t.Parallel()
+
+	testCases := map[string]struct {
+		in       *tfprotov5.ValidateActionConfigResponse
+		expected *tfprotov6.ValidateActionConfigResponse
+	}{
+		"nil": {
+			in:       nil,
+			expected: nil,
+		},
+		"all-valid-fields": {
+			in: &tfprotov5.ValidateActionConfigResponse{
+				Diagnostics: testTfprotov5Diagnostics,
+			},
+			expected: &tfprotov6.ValidateActionConfigResponse{
+				Diagnostics: testTfprotov6Diagnostics,
+			},
+		},
+	}
+
+	for name, testCase := range testCases {
+
+		t.Run(name, func(t *testing.T) {
+			t.Parallel()
+
+			got := tfprotov5tov6.ValidateActionConfigResponse(testCase.in)
+
+			if diff := cmp.Diff(got, testCase.expected); diff != "" {
+				t.Errorf("unexpected difference: %s", diff)
+			}
+		})
+	}
+}
+
 func TestPlanActionRequest(t *testing.T) {
 	t.Parallel()
 

internal/tfprotov6tov5/tfprotov6tov5.go

@@ -1202,6 +1202,27 @@ func LinkedResourceSchema(in *tfprotov6.LinkedResourceSchema) *tfprotov5.LinkedR
 	}
 }
 
+func ValidateActionConfigRequest(in *tfprotov6.ValidateActionConfigRequest) *tfprotov5.ValidateActionConfigRequest {
+	if in == nil {
+		return nil
+	}
+
+	return &tfprotov5.ValidateActionConfigRequest{
+		Config:     DynamicValue(in.Config),
+		ActionType: in.ActionType,
+	}
+}
+
+func ValidateActionConfigResponse(in *tfprotov6.ValidateActionConfigResponse) *tfprotov5.ValidateActionConfigResponse {
+	if in == nil {
+		return nil
+	}
+
+	return &tfprotov5.ValidateActionConfigResponse{
+		Diagnostics: Diagnostics(in.Diagnostics),
+	}
+}
+
 func PlanActionRequest(in *tfprotov6.PlanActionRequest) *tfprotov5.PlanActionRequest {
 	if in == nil {
 		return nil

internal/tfprotov6tov5/tfprotov6tov5_test.go

@@ -3613,6 +3613,78 @@ func TestActionSchema(t *testing.T) {
 	}
 }
 
+func TestValidateActionConfigRequest(t *testing.T) {
+	t.Parallel()
+
+	testCases := map[string]struct {
+		in       *tfprotov6.ValidateActionConfigRequest
+		expected *tfprotov5.ValidateActionConfigRequest
+	}{
+		"nil": {
+			in:       nil,
+			expected: nil,
+		},
+		"all-valid-fields": {
+			in: &tfprotov6.ValidateActionConfigRequest{
+				Config:     &testTfprotov6DynamicValue,
+				ActionType: "test_action",
+			},
+			expected: &tfprotov5.ValidateActionConfigRequest{
+				Config:     &testTfprotov5DynamicValue,
+				ActionType: "test_action",
+			},
+		},
+	}
+
+	for name, testCase := range testCases {
+
+		t.Run(name, func(t *testing.T) {
+			t.Parallel()
+
+			got := tfprotov6tov5.ValidateActionConfigRequest(testCase.in)
+
+			if diff := cmp.Diff(got, testCase.expected); diff != "" {
+				t.Errorf("unexpected difference: %s", diff)
+			}
+		})
+	}
+}
+
+func TestValidateActionConfigResponse(t *testing.T) {
+	t.Parallel()
+
+	testCases := map[string]struct {
+		in       *tfprotov6.ValidateActionConfigResponse
+		expected *tfprotov5.ValidateActionConfigResponse
+	}{
+		"nil": {
+			in:       nil,
+			expected: nil,
+		},
+		"all-valid-fields": {
+			in: &tfprotov6.ValidateActionConfigResponse{
+				Diagnostics: testTfprotov6Diagnostics,
+			},
+			expected: &tfprotov5.ValidateActionConfigResponse{
+				Diagnostics: testTfprotov5Diagnostics,
+			},
+		},
+	}
+
+	for name, testCase := range testCases {
+
+		t.Run(name, func(t *testing.T) {
+			t.Parallel()
+
+			got := tfprotov6tov5.ValidateActionConfigResponse(testCase.in)
+
+			if diff := cmp.Diff(got, testCase.expected); diff != "" {
+				t.Errorf("unexpected difference: %s", diff)
+			}
+		})
+	}
+}
+
 func TestPlanActionRequest(t *testing.T) {
 	t.Parallel()
 

tf5muxserver/mux_server_ValidateActionConfig.go

@@ -0,0 +1,52 @@
+// Copyright (c) HashiCorp, Inc.
+// SPDX-License-Identifier: MPL-2.0
+
+package tf5muxserver
+
+import (
+	"context"
+
+	"github.com/hashicorp/terraform-plugin-go/tfprotov5"
+
+	"github.com/hashicorp/terraform-plugin-mux/internal/logging"
+)
+
+func (s *muxServer) ValidateActionConfig(ctx context.Context, req *tfprotov5.ValidateActionConfigRequest) (*tfprotov5.ValidateActionConfigResponse, error) {
+	rpc := "ValidateActionTypeConfig"
+	ctx = logging.InitContext(ctx)
+	ctx = logging.RpcContext(ctx, rpc)
+
+	server, diags, err := s.getActionServer(ctx, req.ActionType)
+
+	if err != nil {
+		return nil, err
+	}
+
+	if diagnosticsHasError(diags) {
+		return &tfprotov5.ValidateActionConfigResponse{
+			Diagnostics: diags,
+		}, nil
+	}
+
+	// TODO: Remove and call server.ValidateActionConfig below directly once interface becomes required.
+	actionServer, ok := server.(tfprotov5.ActionServer)
+	if !ok {
+		resp := &tfprotov5.ValidateActionConfigResponse{
+			Diagnostics: []*tfprotov5.Diagnostic{
+				{
+					Severity: tfprotov5.DiagnosticSeverityError,
+					Summary:  "ValidateActionConfig Not Implemented",
+					Detail: "A ValidateActionConfig call was received by the provider, however the provider does not implement ValidateActionConfig. " +
+						"Either upgrade the provider to a version that implements ValidateActionConfig or this is a bug in Terraform that should be reported to the Terraform maintainers.",
+				},
+			},
+		}
+
+		return resp, nil
+	}
+
+	ctx = logging.Tfprotov5ProviderServerContext(ctx, server)
+	logging.MuxTrace(ctx, "calling downstream server")
+
+	return actionServer.ValidateActionConfig(ctx, req)
+}