Implement JSON Patch in Xds Translator (#1606)

* Implement JSON Patch in Xds Translator

Relates to #24

Signed-off-by: Arko Dasgupta <arko@tetrate.io>

* use temp variable to unmarshal into

Signed-off-by: Arko Dasgupta <arko@tetrate.io>

* lint

Signed-off-by: Arko Dasgupta <arko@tetrate.io>

* fix test

Signed-off-by: Arko Dasgupta <arko@tetrate.io>

* use apiextensionsv1.JSON

Signed-off-by: Arko Dasgupta <arko@tetrate.io>

* routeConfig test

Signed-off-by: Arko Dasgupta <arko@tetrate.io>

* add entire resource and more test cases

Signed-off-by: Arko Dasgupta <arko@tetrate.io>

* lint

Signed-off-by: Arko Dasgupta <arko@tetrate.io>

* move marshaller out of for loop

Signed-off-by: Arko Dasgupta <arko@tetrate.io>

* address comments

Signed-off-by: Arko Dasgupta <arko@tetrate.io>

---------

Signed-off-by: Arko Dasgupta <arko@tetrate.io>
Co-authored-by: zirain <zirain2009@gmail.com>

go.mod

@@ -7,6 +7,7 @@ require (
 	github.com/davecgh/go-spew v1.1.1
 	github.com/envoyproxy/go-control-plane v0.11.1
 	github.com/envoyproxy/ratelimit v1.4.1-0.20230427142404-e2a87f41d3a7
+	github.com/evanphx/json-patch/v5 v5.6.0
 	github.com/go-logr/logr v1.2.4
 	github.com/go-logr/zapr v1.2.4
 	github.com/golang/protobuf v1.5.3
@@ -25,6 +26,7 @@ require (
 	google.golang.org/protobuf v1.31.0
 	gopkg.in/yaml.v3 v3.0.1
 	k8s.io/api v0.27.3
+	k8s.io/apiextensions-apiserver v0.27.2
 	k8s.io/apimachinery v0.27.3
 	k8s.io/cli-runtime v0.27.3
 	k8s.io/client-go v0.27.3
@@ -45,7 +47,6 @@ require (
 	github.com/emicklei/go-restful/v3 v3.9.0 // indirect
 	github.com/envoyproxy/protoc-gen-validate v1.0.1 // indirect
 	github.com/evanphx/json-patch v4.12.0+incompatible // indirect
-	github.com/evanphx/json-patch/v5 v5.6.0 // indirect
 	github.com/exponent-io/jsonpath v0.0.0-20151013193312-d6023ce2651d // indirect
 	github.com/fsnotify/fsnotify v1.6.0 // indirect
 	github.com/go-asn1-ber/asn1-ber v1.5.4 // indirect
@@ -104,7 +105,6 @@ require (
 	google.golang.org/genproto/googleapis/rpc v0.0.0-20230530153820-e85fd2cbaebc // indirect
 	gopkg.in/inf.v0 v0.9.1 // indirect
 	gopkg.in/yaml.v2 v2.4.0 // indirect
-	k8s.io/apiextensions-apiserver v0.27.2 // indirect
 	k8s.io/component-base v0.27.3 // indirect
 	k8s.io/klog/v2 v2.100.1 // indirect
 	k8s.io/kube-openapi v0.0.0-20230501164219-8b0f38b5fd1f // indirect

internal/ir/xds.go

@@ -11,6 +11,7 @@ import (
 
 	"github.com/tetratelabs/multierror"
 
+	apiextensionsv1 "k8s.io/apiextensions-apiserver/pkg/apis/apiextensions/v1"
 	"k8s.io/apimachinery/pkg/apis/meta/v1/unstructured"
 
 	egv1a1 "github.com/envoyproxy/gateway/api/v1alpha1"
@@ -54,6 +55,9 @@ type Xds struct {
 	TCP []*TCPListener
 	// UDP Listeners exposed by the gateway.
 	UDP []*UDPListener
+	// JSONPatches are the JSON Patches that
+	// are to be applied to generaed Xds linked to the gateway.
+	JSONPatches []*JSONPatchConfig
 }
 
 // Validate the fields within the Xds structure.
@@ -792,3 +796,28 @@ type OpenTelemetryAccessLog struct {
 	Port       uint32            `json:"port"`
 	Resources  map[string]string `json:"resources"`
 }
+
+// JSONPatchConfig defines the configuration for patching a Envoy xDS Resource
+// using JSONPatch semantics
+// +k8s:deepcopy-gen=true
+type JSONPatchConfig struct {
+	// Type is the typed URL of the Envoy xDS Resource
+	Type string `json:"type"`
+	// Name is the name of the resource
+	Name string `json:"name"`
+	// Patch defines the JSON Patch Operation
+	Operation JSONPatchOperation `json:"operation"`
+}
+
+// JSONPatchOperation defines the JSON Patch Operation as defined in
+// https://datatracker.ietf.org/doc/html/rfc6902
+// +k8s:deepcopy-gen=true
+type JSONPatchOperation struct {
+	// Op is the type of operation to perform
+	Op string `json:"op"`
+	// Path is the location of the target document/field where the operation will be performed
+	// Refer to https://datatracker.ietf.org/doc/html/rfc6901 for more details.
+	Path string `json:"path"`
+	// Value is the new value of the path location.
+	Value apiextensionsv1.JSON `json:"value"`
+}