Only apply CRD API conversions for converting between singleton list …

…and embedded objects APIs

Signed-off-by: Fatih Türken <[email protected]>

config/old-singleton-list-apis.txt

@@ -0,0 +1,6 @@
+azuread_application
+azuread_conditional_access_policy
+azuread_group
+azuread_invitation
+azuread_named_location
+azuread_service_principal

config/provider.go

@@ -6,9 +6,12 @@ package config
 
 import (
 	"context"
+	"strings"
+
 	// Note(turkenh): we are importing this to embed provider schema document
 	_ "embed"
 
+	"github.com/crossplane/upjet/pkg/config"
 	ujconfig "github.com/crossplane/upjet/pkg/config"
 	"github.com/crossplane/upjet/pkg/config/conversion"
 	"github.com/crossplane/upjet/pkg/registry/reference"
@@ -44,6 +47,28 @@ var providerSchema string
 //go:embed provider-metadata.yaml
 var providerMetadata string
 
+// oldSingletonListAPIs is a newline-delimited list of Terraform resource
+// names with converted singleton list APIs with at least CRD API version
+// containing the old singleton list API. This is to prevent the API
+// conversion for the newly added resources whose CRD APIs will already
+// use embedded objects instead of the singleton lists and thus, will
+// not possess a CRD API version with the singleton list. Thus, for
+// the newly added resources (resources added after the singleton lists
+// have been converted), we do not need the CRD API conversion
+// functions that convert between singleton lists and embedded objects,
+// but we need only the Terraform conversion functions.
+// This list is immutable and represents the set of resources with the
+// already generated CRD API versions with now converted singleton lists.
+// Because new resources should never have singleton lists in their
+// generated APIs, there should be no need to add them to this list.
+// However, bugs might result in exceptions in the future.
+// Please see:
+// https://github.com/crossplane-contrib/provider-upjet-azuread/pull/123
+// for more context on singleton list to embedded object conversions.
+//
+//go:embed old-singleton-list-apis.txt
+var oldSingletonListAPIs string
+
 // workaround for the TF Google v2.41.0-based no-fork release: We would like to
 // keep the types in the generated CRDs intact
 // (prevent number->int type replacements).
@@ -136,22 +161,41 @@ func resourceList(t map[string]ujconfig.ExternalName) []string {
 }
 
 func bumpVersionsWithEmbeddedLists(pc *ujconfig.Provider) {
+	l := strings.Split(strings.TrimSpace(oldSingletonListAPIs), "\n")
+	oldSLAPIs := make(map[string]struct{}, len(l))
+	for _, n := range l {
+		oldSLAPIs[n] = struct{}{}
+	}
+
 	for name, r := range pc.Resources {
 		r := r
 		// nothing to do if no singleton list has been converted to
 		// an embedded object
 		if len(r.CRDListConversionPaths()) == 0 {
 			continue
 		}
-		r.Version = "v1beta2"
-		// we would like to set the storage version to v1beta1 to facilitate
-		// downgrades.
-		r.SetCRDStorageVersion("v1beta1")
-		r.ControllerReconcileVersion = "v1beta1"
-		r.Conversions = []conversion.Conversion{
-			conversion.NewIdentityConversionExpandPaths(conversion.AllVersions, conversion.AllVersions, []string{"spec.forProvider", "spec.initProvider", "status.atProvider"}, r.CRDListConversionPaths()...),
-			conversion.NewSingletonListConversion("v1beta1", "v1beta2", conversion.DefaultPathPrefixes(), r.CRDListConversionPaths(), conversion.ToEmbeddedObject),
-			conversion.NewSingletonListConversion("v1beta2", "v1beta1", conversion.DefaultPathPrefixes(), r.CRDListConversionPaths(), conversion.ToSingletonList)}
+		if _, ok := oldSLAPIs[name]; ok {
+			r.Version = "v1beta2"
+			r.PreviousVersions = []string{"v1beta1"}
+			// we would like to set the storage version to v1beta1 to facilitate
+			// downgrades.
+			r.SetCRDStorageVersion("v1beta1")
+			// because the controller reconciles on the API version with the singleton list API,
+			// no need for a Terraform conversion.
+			r.ControllerReconcileVersion = "v1beta1"
+			r.Conversions = []conversion.Conversion{
+				conversion.NewIdentityConversionExpandPaths(conversion.AllVersions, conversion.AllVersions, conversion.DefaultPathPrefixes(), r.CRDListConversionPaths()...),
+				conversion.NewSingletonListConversion("v1beta1", "v1beta2", conversion.DefaultPathPrefixes(), r.CRDListConversionPaths(), conversion.ToEmbeddedObject),
+				conversion.NewSingletonListConversion("v1beta2", "v1beta1", conversion.DefaultPathPrefixes(), r.CRDListConversionPaths(), conversion.ToSingletonList)}
+		} else {
+			// the controller will be reconciling on the CRD API version
+			// with the converted API (with embedded objects in place of
+			// singleton lists), so we need the appropriate Terraform
+			// converter in this case.
+			r.TerraformConversions = []config.TerraformConversion{
+				config.NewTFSingletonConversion(),
+			}
+		}
 		pc.Resources[name] = r
 	}
 }