Add config.Resource. ServerSideApplyMergeStrategies to configure the SSA Merge Strategies

pkg/config/common.go

@@ -77,17 +77,18 @@ func DefaultResource(name string, terraformSchema *schema.Resource, terraformReg
 	}
 
 	r := &Resource{
-		Name:                 name,
-		TerraformResource:    terraformSchema,
-		MetaResource:         terraformRegistry,
-		ShortGroup:           group,
-		Kind:                 kind,
-		Version:              "v1alpha1",
-		ExternalName:         NameAsIdentifier,
-		References:           map[string]Reference{},
-		Sensitive:            NopSensitive,
-		UseAsync:             true,
-		SchemaElementOptions: make(map[string]*SchemaElementOption),
+		Name:                           name,
+		TerraformResource:              terraformSchema,
+		MetaResource:                   terraformRegistry,
+		ShortGroup:                     group,
+		Kind:                           kind,
+		Version:                        "v1alpha1",
+		ExternalName:                   NameAsIdentifier,
+		References:                     make(References),
+		Sensitive:                      NopSensitive,
+		UseAsync:                       true,
+		SchemaElementOptions:           make(SchemaElementOptions),
+		ServerSideApplyMergeStrategies: make(ServerSideApplyMergeStrategies),
 	}
 	for _, f := range opts {
 		f(r)

pkg/config/common_test.go

@@ -33,15 +33,16 @@ func TestDefaultResource(t *testing.T) {
 				name: "aws_ec2_instance",
 			},
 			want: &Resource{
-				Name:                 "aws_ec2_instance",
-				ShortGroup:           "ec2",
-				Kind:                 "Instance",
-				Version:              "v1alpha1",
-				ExternalName:         NameAsIdentifier,
-				References:           map[string]Reference{},
-				Sensitive:            NopSensitive,
-				UseAsync:             true,
-				SchemaElementOptions: SchemaElementOptions{},
+				Name:                           "aws_ec2_instance",
+				ShortGroup:                     "ec2",
+				Kind:                           "Instance",
+				Version:                        "v1alpha1",
+				ExternalName:                   NameAsIdentifier,
+				References:                     map[string]Reference{},
+				Sensitive:                      NopSensitive,
+				UseAsync:                       true,
+				SchemaElementOptions:           SchemaElementOptions{},
+				ServerSideApplyMergeStrategies: ServerSideApplyMergeStrategies{},
 			},
 		},
 		"TwoSectionsName": {
@@ -50,15 +51,16 @@ func TestDefaultResource(t *testing.T) {
 				name: "aws_instance",
 			},
 			want: &Resource{
-				Name:                 "aws_instance",
-				ShortGroup:           "aws",
-				Kind:                 "Instance",
-				Version:              "v1alpha1",
-				ExternalName:         NameAsIdentifier,
-				References:           map[string]Reference{},
-				Sensitive:            NopSensitive,
-				UseAsync:             true,
-				SchemaElementOptions: SchemaElementOptions{},
+				Name:                           "aws_instance",
+				ShortGroup:                     "aws",
+				Kind:                           "Instance",
+				Version:                        "v1alpha1",
+				ExternalName:                   NameAsIdentifier,
+				References:                     map[string]Reference{},
+				Sensitive:                      NopSensitive,
+				UseAsync:                       true,
+				SchemaElementOptions:           SchemaElementOptions{},
+				ServerSideApplyMergeStrategies: ServerSideApplyMergeStrategies{},
 			},
 		},
 		"NameWithPrefixAcronym": {
@@ -67,15 +69,16 @@ func TestDefaultResource(t *testing.T) {
 				name: "aws_db_sql_server",
 			},
 			want: &Resource{
-				Name:                 "aws_db_sql_server",
-				ShortGroup:           "db",
-				Kind:                 "SQLServer",
-				Version:              "v1alpha1",
-				ExternalName:         NameAsIdentifier,
-				References:           map[string]Reference{},
-				Sensitive:            NopSensitive,
-				UseAsync:             true,
-				SchemaElementOptions: SchemaElementOptions{},
+				Name:                           "aws_db_sql_server",
+				ShortGroup:                     "db",
+				Kind:                           "SQLServer",
+				Version:                        "v1alpha1",
+				ExternalName:                   NameAsIdentifier,
+				References:                     map[string]Reference{},
+				Sensitive:                      NopSensitive,
+				UseAsync:                       true,
+				SchemaElementOptions:           SchemaElementOptions{},
+				ServerSideApplyMergeStrategies: ServerSideApplyMergeStrategies{},
 			},
 		},
 		"NameWithSuffixAcronym": {
@@ -84,15 +87,16 @@ func TestDefaultResource(t *testing.T) {
 				name: "aws_db_server_id",
 			},
 			want: &Resource{
-				Name:                 "aws_db_server_id",
-				ShortGroup:           "db",
-				Kind:                 "ServerID",
-				Version:              "v1alpha1",
-				ExternalName:         NameAsIdentifier,
-				References:           map[string]Reference{},
-				Sensitive:            NopSensitive,
-				UseAsync:             true,
-				SchemaElementOptions: SchemaElementOptions{},
+				Name:                           "aws_db_server_id",
+				ShortGroup:                     "db",
+				Kind:                           "ServerID",
+				Version:                        "v1alpha1",
+				ExternalName:                   NameAsIdentifier,
+				References:                     map[string]Reference{},
+				Sensitive:                      NopSensitive,
+				UseAsync:                       true,
+				SchemaElementOptions:           SchemaElementOptions{},
+				ServerSideApplyMergeStrategies: ServerSideApplyMergeStrategies{},
 			},
 		},
 		"NameWithMultipleAcronyms": {
@@ -101,15 +105,16 @@ func TestDefaultResource(t *testing.T) {
 				name: "aws_db_sql_server_id",
 			},
 			want: &Resource{
-				Name:                 "aws_db_sql_server_id",
-				ShortGroup:           "db",
-				Kind:                 "SQLServerID",
-				Version:              "v1alpha1",
-				ExternalName:         NameAsIdentifier,
-				References:           map[string]Reference{},
-				Sensitive:            NopSensitive,
-				UseAsync:             true,
-				SchemaElementOptions: SchemaElementOptions{},
+				Name:                           "aws_db_sql_server_id",
+				ShortGroup:                     "db",
+				Kind:                           "SQLServerID",
+				Version:                        "v1alpha1",
+				ExternalName:                   NameAsIdentifier,
+				References:                     map[string]Reference{},
+				Sensitive:                      NopSensitive,
+				UseAsync:                       true,
+				SchemaElementOptions:           SchemaElementOptions{},
+				ServerSideApplyMergeStrategies: ServerSideApplyMergeStrategies{},
 			},
 		},
 	}

pkg/config/resource.go

@@ -24,6 +24,54 @@ import (
 	"github.com/crossplane/upjet/pkg/registry"
 )
 
+// A ListType is a type of list.
+type ListType string
+
+// Types of lists.
+const (
+	// ListTypeAtomic means the entire list is replaced during merge. At any
+	// point in time, a single manager owns the list.
+	ListTypeAtomic ListType = "atomic"
+
+	// ListTypeSet can be granularly merged, and different managers can own
+	// different elements in the list. The list can include only scalar
+	// elements.
+	ListTypeSet ListType = "set"
+
+	// ListTypeMap can be granularly merged, and different managers can own
+	// different elements in the list. The list can include only nested types
+	// (i.e. objects).
+	ListTypeMap ListType = "map"
+)
+
+// A MapType is a type of map.
+type MapType string
+
+// Types of maps.
+const (
+	// MapTypeAtomic means that the map can only be entirely replaced by a
+	// single manager.
+	MapTypeAtomic MapType = "atomic"
+
+	// MapTypeGranular means that the map supports separate managers updating
+	// individual fields.
+	MapTypeGranular MapType = "granular"
+)
+
+// A StructType is a type of struct.
+type StructType string
+
+// Struct types.
+const (
+	// StructTypeAtomic means that the struct can only be entirely replaced by a
+	// single manager.
+	StructTypeAtomic StructType = "atomic"
+
+	// StructTypeGranular means that the struct supports separate managers
+	// updating individual fields.
+	StructTypeGranular StructType = "granular"
+)
+
 // SetIdentifierArgumentsFn sets the name of the resource in Terraform attributes map,
 // i.e. Main HCL file.
 type SetIdentifierArgumentsFn func(base map[string]any, externalName string)
@@ -266,6 +314,60 @@ func setExternalTagsWithPaved(externalTags map[string]string, paved *fieldpath.P
 	return pavedByte, nil
 }
 
+type InjectedKey struct {
+	Key          string
+	DefaultValue string
+}
+
+// ListMapKeys is the list map keys when the server-side apply merge strategy
+// islistType=map.
+type ListMapKeys struct {
+	// InjectedKey can be used to inject the specified index key
+	// into the generated CRD schema for the list object when
+	// the SSA merge strategy for the parent list is `map`.
+	// If a non-zero `InjectedKey` is specified, then a field of type string with
+	// the specified name is injected into the Terraform schema and used as
+	// a list map key together with any other existing keys specified in `Keys`.
+	InjectedKey InjectedKey
+	// Keys is the set of list map keys to be used while SSA merges list items.
+	// If InjectedKey is non-zero, then it's automatically put into Keys and
+	// you must not specify the InjectedKey in Keys explicitly.
+	Keys []string
+}
+
+// ListMergeStrategy configures the corresponding field as list
+// and configures its server-side apply merge strategy.
+type ListMergeStrategy struct {
+	// ListMapKeys is the list map keys when the SSA merge strategy is
+	// `listType=map`.  The keys specified here must be a set of scalar Terraform
+	// argument names to be used as the list map keys for the object list.
+	ListMapKeys ListMapKeys
+	// MergeStrategy is the SSA merge strategy for an object list. Valid values
+	// are: `atomic`, `set` and `map`
+	MergeStrategy ListType
+}
+
+// MergeStrategy configures the server-side apply merge strategy for the
+// corresponding field. One and only one of the pointer members can be set
+// and the specified merge strategy configuration must match the field's
+// type, e.g., you cannot set MapMergeStrategy for a field of type list.
+type MergeStrategy struct {
+	ListMergeStrategy   ListMergeStrategy
+	MapMergeStrategy    MapType
+	StructMergeStrategy StructType
+}
+
+// ServerSideApplyMergeStrategies configures the server-side apply merge strategy
+// for the field at the specified path as the map key. The key is
+// a Terraform configuration argument path such as a.b.c, without any
+// index notation (i.e., array/map components do not need indices).
+// It's an error to set a configuration option which does not match
+// the object type at the specified path or to leave the corresponding
+// configuration entry empty. For example, if the field at path a.b.c is
+// a list, then ListMergeStrategy must be set and it should be the only
+// configuration entry set.
+type ServerSideApplyMergeStrategies map[string]MergeStrategy
+
 // Resource is the set of information that you can override at different steps
 // of the code generation pipeline.
 type Resource struct {
@@ -338,6 +440,12 @@ type Resource struct {
 	// Terraform InstanceDiff is computed during reconciliation.
 	TerraformCustomDiff CustomDiff
 
+	// ServerSideApplyMergeStrategies configures the server-side apply merge
+	// strategy for the fields at the given map keys. The map key is
+	// a Terraform configuration argument path such as a.b.c, without any
+	// index notation (i.e., array/map components do not need indices).
+	ServerSideApplyMergeStrategies ServerSideApplyMergeStrategies
+
 	// useNoForkClient indicates that a no-fork external client should
 	// be generated instead of the Terraform CLI-forking client.
 	useNoForkClient bool

pkg/types/builder.go

@@ -27,6 +27,9 @@ const (
 
 	// ref: https://kubernetes.io/docs/tasks/extend-kubernetes/custom-resources/custom-resource-definitions/#validation-rules
 	celEscapeSequence = "__%s__"
+	// description for an injected list map key field in the context of the
+	// server-side apply object list merging
+	descriptionInjectedKey = "This is an injected field with a default value for being able to merge items of the parent object list."
 )
 
 var (
@@ -67,6 +70,10 @@ func NewBuilder(pkg *types.Package) *Builder {
 
 // Build returns parameters and observation types built out of Terraform schema.
 func (g *Builder) Build(cfg *config.Resource) (Generated, error) {
+	if err := injectServerSideApplyListMergeKeys(cfg); err != nil {
+		return Generated{}, errors.Wrapf(err, "cannot inject server-side apply merge keys for resource %q", cfg.Name)
+	}
+
 	fp, ap, ip, err := g.buildResource(cfg.TerraformResource, cfg, nil, nil, false, cfg.Kind)
 	return Generated{
 		Types:            g.genTypes,
@@ -75,7 +82,46 @@ func (g *Builder) Build(cfg *config.Resource) (Generated, error) {
 		InitProviderType: ip,
 		AtProviderType:   ap,
 		ValidationRules:  g.validationRules,
-	}, errors.Wrapf(err, "cannot build the Types")
+	}, errors.Wrapf(err, "cannot build the Types for resource %q", cfg.Name)
+}
+
+func injectServerSideApplyListMergeKeys(cfg *config.Resource) error { //nolint:gocyclo // Easier to follow the logic in a single function
+	for f, s := range cfg.ServerSideApplyMergeStrategies {
+		if s.ListMergeStrategy.MergeStrategy != config.ListTypeMap {
+			continue
+		}
+		if s.ListMergeStrategy.ListMapKeys.InjectedKey.Key == "" && len(s.ListMergeStrategy.ListMapKeys.Keys) == 0 {
+			return errors.Errorf("list map keys configuration for the object list %q is empty", f)
+		}
+		if s.ListMergeStrategy.ListMapKeys.InjectedKey.Key == "" {
+			continue
+		}
+		sch := config.GetSchema(cfg.TerraformResource, f)
+		if sch == nil {
+			return errors.Errorf("cannot find the Terraform schema for the argument at the path %q", f)
+		}
+		if sch.Type != schema.TypeList && sch.Type != schema.TypeSet {
+			return errors.Errorf("fieldpath %q is not a Terraform list or set", f)
+		}
+		el, ok := sch.Elem.(*schema.Resource)
+		if !ok {
+			return errors.Errorf("fieldpath %q is a Terraform list or set but its element type is not a Terraform *schema.Resource", f)
+		}
+		for k := range el.Schema {
+			if k == s.ListMergeStrategy.ListMapKeys.InjectedKey.Key {
+				return errors.Errorf("element schema for the object list %q already contains the argument key %q", f, k)
+			}
+		}
+		el.Schema[s.ListMergeStrategy.ListMapKeys.InjectedKey.Key] = &schema.Schema{
+			Type:        schema.TypeString,
+			Required:    true,
+			Description: descriptionInjectedKey,
+		}
+		if s.ListMergeStrategy.ListMapKeys.InjectedKey.DefaultValue != "" {
+			el.Schema[s.ListMergeStrategy.ListMapKeys.InjectedKey.Key].Default = s.ListMergeStrategy.ListMapKeys.InjectedKey.DefaultValue
+		}
+	}
+	return nil
 }
 
 func (g *Builder) buildResource(res *schema.Resource, cfg *config.Resource, tfPath []string, xpPath []string, asBlocksMode bool, names ...string) (*types.Named, *types.Named, *types.Named, error) { //nolint:gocyclo

pkg/types/builder_test.go

@@ -314,6 +314,7 @@ func TestBuild(t *testing.T) {
 		"Invalid_Sensitive_Fields": {
 			args: args{
 				cfg: &config.Resource{
+					Name: "test_resource",
 					TerraformResource: &schema.Resource{
 						Schema: map[string]*schema.Schema{
 							"key_1": {
@@ -325,7 +326,7 @@ func TestBuild(t *testing.T) {
 				},
 			},
 			want: want{
-				err: errors.Wrapf(fmt.Errorf(`got type %q for field %q, only types "string", "*string", []string, []*string, "map[string]string" and "map[string]*string" supported as sensitive`, "*float64", "Key1"), "cannot build the Types"),
+				err: errors.Wrapf(fmt.Errorf(`got type %q for field %q, only types "string", "*string", []string, []*string, "map[string]string" and "map[string]*string" supported as sensitive`, "*float64", "Key1"), `cannot build the Types for resource "test_resource"`),
 			},
 		},
 		"References": {
@@ -361,6 +362,7 @@ func TestBuild(t *testing.T) {
 		"Invalid_Schema_Type": {
 			args: args{
 				cfg: &config.Resource{
+					Name: "test_resource",
 					TerraformResource: &schema.Resource{
 						Schema: map[string]*schema.Schema{
 							"name": {
@@ -372,7 +374,7 @@ func TestBuild(t *testing.T) {
 				},
 			},
 			want: want{
-				err: errors.Wrapf(errors.Wrapf(errors.Errorf("invalid schema type %s", "TypeInvalid"), "cannot infer type from schema of field %s", "name"), "cannot build the Types"),
+				err: errors.Wrapf(errors.Wrapf(errors.Errorf("invalid schema type %s", "TypeInvalid"), "cannot infer type from schema of field %s", "name"), `cannot build the Types for resource "test_resource"`),
 			},
 		},
 		"Validation_Rules_With_Keywords": {