feat(xr): Introduce xr patch --xrd

cmd/crossplane/render/xr/cmd.go

@@ -35,13 +35,13 @@ import (
 	"github.com/crossplane/crossplane-runtime/v2/pkg/errors"
 	"github.com/crossplane/crossplane-runtime/v2/pkg/logging"
 	"github.com/crossplane/crossplane-runtime/v2/pkg/resource/unstructured/composed"
-	"github.com/crossplane/crossplane-runtime/v2/pkg/xcrd"
 
 	apiextensionsv1 "github.com/crossplane/crossplane/apis/v2/apiextensions/v1"
 	pkgv1 "github.com/crossplane/crossplane/apis/v2/pkg/v1"
 
 	"github.com/crossplane/cli/v2/cmd/crossplane/render"
 	"github.com/crossplane/cli/v2/cmd/crossplane/render/contextfn"
+	xrcmd "github.com/crossplane/cli/v2/cmd/crossplane/xr"
 	"github.com/crossplane/cli/v2/internal/async"
 	"github.com/crossplane/cli/v2/internal/dependency"
 	"github.com/crossplane/cli/v2/internal/project"
@@ -169,13 +169,8 @@ func (c *Cmd) Run(k *kong.Context, log logging.Logger, sp terminal.SpinnerPrinte
 			return errors.Wrapf(err, "cannot load XRD from %q", c.XRD)
 		}
 
-		crd, err := xcrd.ForCompositeResource(xrd)
-		if err != nil {
-			return errors.Wrapf(err, "cannot derive composite CRD from XRD %q", xrd.GetName())
-		}
-
-		if err := render.DefaultValues(xr.UnstructuredContent(), xr.GetAPIVersion(), *crd); err != nil {
-			return errors.Wrapf(err, "cannot default values for XR %q", xr.GetName())
+		if err := xrcmd.ApplyXRDDefaults(xr.GetUnstructured(), xrd); err != nil {
+			return errors.Wrapf(err, "cannot apply XRD defaults to XR %q", xr.GetName())
 		}
 	}
 

cmd/crossplane/xr/help/patch.md

@@ -0,0 +1,26 @@
+The `xr patch` command applies XR-level patches to a Composite Resource (XR).
+
+It reads the XR from a file (or stdin), applies the requested patches, and
+writes the result to stdout or to a file. At least one patching flag must be
+set; today the only one is `--xrd`, which applies default values from an XRD's
+`openAPIV3Schema` to the XR. More patching flags will be added in the future.
+
+## Examples
+
+Apply default values from an XRD to an XR:
+
+```shell
+crossplane xr patch xr.yaml --xrd xrd.yaml
+```
+
+Patch an XR from stdin:
+
+```shell
+cat xr.yaml | crossplane xr patch - --xrd xrd.yaml
+```
+
+Write the patched XR to a file:
+
+```shell
+crossplane xr patch xr.yaml --xrd xrd.yaml -o patched.yaml
+```

cmd/crossplane/xr/patch.go

@@ -0,0 +1,104 @@
+/*
+Copyright 2026 The Crossplane Authors.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+package xr
+
+import (
+	"github.com/alecthomas/kong"
+	"github.com/spf13/afero"
+	"k8s.io/apimachinery/pkg/apis/meta/v1/unstructured"
+	"sigs.k8s.io/yaml"
+
+	"github.com/crossplane/crossplane-runtime/v2/pkg/errors"
+
+	commonIO "github.com/crossplane/cli/v2/cmd/crossplane/convert/io"
+	"github.com/crossplane/cli/v2/cmd/crossplane/render"
+
+	_ "embed"
+)
+
+//go:embed help/patch.md
+var patchHelp string
+
+type patchCmd struct {
+	// Arguments.
+	InputFile string `arg:"" default:"-" help:"The XR YAML file to patch, or '-' for stdin." optional:"" predictor:"file" type:"path"`
+
+	// Output flags.
+	OutputFile string `help:"The file to write the patched XR YAML to. Defaults to stdout." placeholder:"PATH" predictor:"file" short:"o" type:"path"`
+
+	// Patching flags.
+	XRD string `help:"A YAML file specifying the CompositeResourceDefinition (XRD) whose schema defaults are applied to the XR." name:"xrd" placeholder:"PATH" predictor:"file" type:"path"`
+
+	fs afero.Fs
+}
+
+func (c *patchCmd) Help() string {
+	return patchHelp
+}
+
+// AfterApply implements kong.AfterApply.
+func (c *patchCmd) AfterApply() error {
+	c.fs = afero.NewOsFs()
+	return nil
+}
+
+// Run runs the patch command.
+func (c *patchCmd) Run(k *kong.Context) error {
+	if c.XRD == "" {
+		return errors.New("no patching flag provided: at least one of --xrd must be set")
+	}
+
+	xrData, err := commonIO.Read(c.fs, c.InputFile)
+	if err != nil {
+		return err
+	}
+
+	xr := &unstructured.Unstructured{}
+	if err := yaml.Unmarshal(xrData, xr); err != nil {
+		return errors.Wrap(err, "cannot unmarshal XR")
+	}
+
+	xrd, err := render.LoadXRD(c.fs, c.XRD)
+	if err != nil {
+		return errors.Wrapf(err, "cannot load XRD from %q", c.XRD)
+	}
+
+	if err := ApplyXRDDefaults(xr, xrd); err != nil {
+		return errors.Wrapf(err, "cannot apply XRD defaults to XR %q", xr.GetName())
+	}
+
+	b, err := yaml.Marshal(xr)
+	if err != nil {
+		return errors.Wrap(err, "cannot marshal patched XR")
+	}
+
+	data := append([]byte("---\n"), b...)
+
+	if c.OutputFile != "" {
+		if err := afero.WriteFile(c.fs, c.OutputFile, data, 0o644); err != nil {
+			return errors.Wrapf(err, "cannot write output file %q", c.OutputFile)
+		}
+
+		return nil
+	}
+
+	if _, err := k.Stdout.Write(data); err != nil {
+		return errors.Wrap(err, "cannot write output")
+	}
+
+	return nil
+}

cmd/crossplane/xr/xr.go

@@ -20,4 +20,5 @@ package xr
 // Cmd contains XR subcommands.
 type Cmd struct {
 	Generate generateCmd `cmd:"" help:"Generate a Composite Resource (XR) from a Claim."`
+	Patch    patchCmd    `cmd:"" help:"Patch a Composite Resource (XR) with additional configurations."`
 }

cmd/crossplane/xr/xrd.go

@@ -0,0 +1,81 @@
+/*
+Copyright 2026 The Crossplane Authors.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+package xr
+
+import (
+	"k8s.io/apiextensions-apiserver/pkg/apis/apiextensions"
+	extv1 "k8s.io/apiextensions-apiserver/pkg/apis/apiextensions/v1"
+	schema "k8s.io/apiextensions-apiserver/pkg/apiserver/schema"
+	structuraldefaulting "k8s.io/apiextensions-apiserver/pkg/apiserver/schema/defaulting"
+	"k8s.io/apimachinery/pkg/apis/meta/v1/unstructured"
+
+	"github.com/crossplane/crossplane-runtime/v2/pkg/errors"
+	"github.com/crossplane/crossplane-runtime/v2/pkg/xcrd"
+
+	apiextensionsv1 "github.com/crossplane/crossplane/apis/v2/apiextensions/v1"
+)
+
+// ApplyXRDDefaults applies default values from an XRD's openAPIV3Schema to an
+// XR. The XR is mutated in place.
+//
+// This is the canonical XRD-defaulting entry point for the cli; downstream
+// commands and tools (e.g. `crossplane render xr --xrd`) call into this
+// function rather than re-implementing the schema-defaulting routine.
+func ApplyXRDDefaults(xr *unstructured.Unstructured, xrdef *apiextensionsv1.CompositeResourceDefinition) error {
+	crd, err := xcrd.ForCompositeResource(xrdef)
+	if err != nil {
+		return errors.Wrapf(err, "cannot derive CRD from XRD %q", xrdef.GetName())
+	}
+
+	return DefaultValues(xr.UnstructuredContent(), xr.GetAPIVersion(), *crd)
+}
+
+// DefaultValues sets default values on the XR based on the CRD schema.
+//
+// Callers starting from an XRD should prefer ApplyXRDDefaults; this is the
+// lower-level routine for callers that already have a CRD in hand.
+func DefaultValues(xr map[string]any, apiVersion string, crd extv1.CustomResourceDefinition) error {
+	var (
+		k       apiextensions.JSONSchemaProps
+		version *extv1.CustomResourceDefinitionVersion
+	)
+
+	for _, vr := range crd.Spec.Versions {
+		checkAPIVersion := crd.Spec.Group + "/" + vr.Name
+		if checkAPIVersion == apiVersion {
+			version = &vr
+			break
+		}
+	}
+
+	if version == nil {
+		return errors.Errorf("the specified API version '%s' does not exist in the XRD", apiVersion)
+	}
+
+	if err := extv1.Convert_v1_JSONSchemaProps_To_apiextensions_JSONSchemaProps(version.Schema.OpenAPIV3Schema, &k, nil); err != nil {
+		return err
+	}
+
+	crdWithDefaults, err := schema.NewStructural(&k)
+	if err != nil {
+		return err
+	}
+
+	structuraldefaulting.Default(xr, crdWithDefaults)
+
+	return nil
+}

cmd/crossplane/render/xrd_test.go → cmd/crossplane/xr/xrd_test.go

@@ -1,4 +1,20 @@
-package render
+/*
+Copyright 2026 The Crossplane Authors.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+package xr
 
 import (
 	"testing"