feat: add jsonpatch library

Taskfile.yaml

@@ -5,5 +5,7 @@ includes:
     taskfile: hack/common/Taskfile_library.yaml
     flatten: true
     vars:
-      CODE_DIRS: '{{.ROOT_DIR}}/pkg/...'
+      NESTED_MODULES: api
+      API_DIRS: '{{.ROOT_DIR}}/api/...'
+      CODE_DIRS: '{{.ROOT_DIR}}/pkg/... {{.ROOT_DIR}}/api/...'
       GENERATE_DOCS_INDEX: "true"

api/go.mod

@@ -0,0 +1,27 @@
+module github.com/openmcp-project/controller-utils/api
+
+go 1.24.2
+
+require github.com/fluxcd/pkg/apis/kustomize v1.10.0
+
+require (
+	github.com/fxamacker/cbor/v2 v2.7.0 // indirect
+	github.com/go-logr/logr v1.4.2 // indirect
+	github.com/gogo/protobuf v1.3.2 // indirect
+	github.com/json-iterator/go v1.1.12 // indirect
+	github.com/kr/pretty v0.3.1 // indirect
+	github.com/modern-go/concurrent v0.0.0-20180306012644-bacd9c7ef1dd // indirect
+	github.com/modern-go/reflect2 v1.0.2 // indirect
+	github.com/x448/float16 v0.8.4 // indirect
+	golang.org/x/net v0.38.0 // indirect
+	golang.org/x/text v0.23.0 // indirect
+	gopkg.in/inf.v0 v0.9.1 // indirect
+	k8s.io/apiextensions-apiserver v0.33.2 // indirect
+	k8s.io/apimachinery v0.33.2 // indirect
+	k8s.io/klog/v2 v2.130.1 // indirect
+	k8s.io/utils v0.0.0-20241104100929-3ea5e8cea738 // indirect
+	sigs.k8s.io/json v0.0.0-20241010143419-9aa6b5e7a4b3 // indirect
+	sigs.k8s.io/randfill v1.0.0 // indirect
+	sigs.k8s.io/structured-merge-diff/v4 v4.6.0 // indirect
+	sigs.k8s.io/yaml v1.4.0 // indirect
+)

api/go.sum

@@ -0,0 +1,98 @@
+github.com/creack/pty v1.1.9/go.mod h1:oKZEueFk5CKHvIhNR5MUki03XCEU+Q6VDXinZuGJ33E=
+github.com/davecgh/go-spew v1.1.0/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
+github.com/davecgh/go-spew v1.1.1 h1:vj9j/u1bqnvCEfJOwUhtlOARqs3+rkHYY13jYWTU97c=
+github.com/davecgh/go-spew v1.1.1/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
+github.com/fluxcd/pkg/apis/kustomize v1.10.0 h1:47EeSzkQvlQZdH92vHMe2lK2iR8aOSEJq95avw5idts=
+github.com/fluxcd/pkg/apis/kustomize v1.10.0/go.mod h1:UsqMV4sqNa1Yg0pmTsdkHRJr7bafBOENIJoAN+3ezaQ=
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+github.com/go-logr/logr v1.4.2 h1:6pFjapn8bFcIbiKo3XT4j/BhANplGihG6tvd+8rYgrY=
+github.com/go-logr/logr v1.4.2/go.mod h1:9T104GzyrTigFIr8wt5mBrctHMim0Nb2HLGrmQ40KvY=
+github.com/gogo/protobuf v1.3.2 h1:Ov1cvc58UF3b5XjBnZv7+opcTcQFZebYjWzi34vdm4Q=
+github.com/gogo/protobuf v1.3.2/go.mod h1:P1XiOD3dCwIKUDQYPy72D8LYyHL2YPYrpS2s69NZV8Q=
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api/jsonpatch/types.go

@@ -0,0 +1,30 @@
+// +kubebuilder:object:generate=true
+package jsonpatch
+
+import (
+	"github.com/fluxcd/pkg/apis/kustomize"
+)
+
+// JSONPatch represents a JSON patch operation.
+// Technically, a single JSON patch (as defined by RFC 6902) is a list of patch operations.
+// Opposed to that, this type represents a single operation. Use the JSONPatches type for a list of operations instead.
+type JSONPatch = kustomize.JSON6902
+
+// JSONPatches is a list of JSON patch operations.
+// This is technically a 'JSON patch' as defined in RFC 6902.
+type JSONPatches []JSONPatch
+
+const (
+	// ADD is the constant for the JSONPatch 'add' operation.
+	ADD = "add"
+	// REMOVE is the constant for the JSONPatch 'remove' operation.
+	REMOVE = "remove"
+	// REPLACE is the constant for the JSONPatch 'replace' operation.
+	REPLACE = "replace"
+	// MOVE is the constant for the JSONPatch 'move' operation.
+	MOVE = "move"
+	// COPY is the constant for the JSONPatch 'copy' operation.
+	COPY = "copy"
+	// TEST is the constant for the JSONPatch 'test' operation.
+	TEST = "test"
+)

docs/README.md

@@ -9,6 +9,7 @@
 - [Controller Utility Functions](libs/controller.md)
 - [Custom Resource Definitions](libs/crds.md)
 - [Error Handling](libs/errors.md)
+- [JSON Patch](libs/jsonpatch.md)
 - [Logging](libs/logging.md)
 - [Key-Value Pairs](libs/pairs.md)
 - [Readiness Checks](libs/readiness.md)

docs/libs/jsonpatch.md

@@ -0,0 +1,115 @@
+# JSON Patch
+
+The `api/jsonpatch` package contains a `JSONPatches` type that represents a [JSON Patch](https://datatracker.ietf.org/doc/html/rfc6902).
+The type is ready to be used in a kubernetes resource type.
+
+The corresponding `pkg/jsonpatch` package contains helper functions to apply JSON patches specified via the aforementioned API type to a given JSON document or arbitrary go type.
+
+## Embedding the API Type
+
+```golang
+import jpapi "github.com/openmcp-project/controller-utils/api/jsonpatch"
+
+type MyTypeSpec struct {
+  Patches jpapi.JSONPatches `json:"patches"`
+}
+```
+
+## Patch Syntax
+
+The `pkg/jsonpatch` package handles JSON patches in form of the `JSONPatches` type from the `api/jsonpatch` package. The type can be safely embedded in k8s resources.
+```yaml
+patches:
+- op: add
+  path: /foo/bar
+  value: foobar
+- op: copy
+  path: /foo/baz
+  from: /foo/bar
+```
+
+`op` and `path` are required for each patch, `value` and `from` depend on the chosen operation.
+Valid operations are `add`, `remove`, `replace`, `move`, `copy`, and `test`.
+
+### Path Notation
+
+The are two options for the notation of the `path` attribute:
+
+#### JSON Pointer Notation
+
+The first option is the JSON Pointer notation as described in [RFC 6901](https://datatracker.ietf.org/doc/html/rfc6901). Basically, each path segment is prefixed with `/`, with no differentiation between object fields and array indices. 
+
+There are two special characters which need to be substituted:
+- `~` has to be written as `~0`
+- `/` has to be written as `~1`
+
+Examples:
+- `/foo/bar`
+- `/mylist/0/asdf`
+- `/metadata/annotations/foo.bar.baz~1foobar`
+
+#### JSON Path Notation
+
+The second option is a simplified variant of the JSON Path notation as described in [RFC 9535](https://datatracker.ietf.org/doc/html/rfc9535). While the RFC specifies a full query language with function evaluation, the implementation here just allows referencing a single path.
+
+In short:
+- path segments are separated by `.` or by using `[...]`
+  - the leading `.` is optional
+- backslashes `\` are used to escape the special characters `\`, `.`, `[`, `]`, `'`, and `"`
+- if the bracket notation is used to separate a path segment, single `'` or double `"` quotes may be used within the brackets
+  - the quote character has to immediately follow the opening bracket and immediately precede the closing bracket
+  - no escaping is required within brackets with quotes
+
+The table below shows a few examples of paths in the JSON Path notation and the corresponding JSON Pointer notation they are converted into.
+| JSON Path Notation | JSON Pointer Notation |
+| --- | --- |
+| `.metadata.annotations.foo\.bar\.baz/foobar` | `/metadata/annotations/foo.bar.baz~1foobar` |
+| `metadata.annotations.foo\.bar\.baz/foobar` | `/metadata/annotations/foo.bar.baz~1foobar` |
+| `.metadata.annotations[foo\.bar\.baz/foobar]` | `/metadata/annotations/foo.bar.baz~1foobar` |
+| `metadata.annotations["foo.bar.baz/foobar"]` | `/metadata/annotations/foo.bar.baz~1foobar` |
+| `.metadata[annotations]['foo.bar.baz/foobar']` | `/metadata/annotations/foo.bar.baz~1foobar` |
+| `.mylist[0].asdf` | `/mylist/0/asdf` |
+| `mylist.0.asdf` | `/mylist/0/asdf` |
+
+## Applying the Patches
+
+### To a JSON Document
+
+```golang
+import "github.com/openmcp-project/controller-utils/pkg/jsonpatch"
+
+// mytype.Spec is of type MyTypeSpec as defined in the above example
+patch := jsonpatch.New(mytype.Spec.Patches)
+// doc and modified are of type []byte
+modified, err := patch.Apply(doc)
+```
+
+### To an Arbitrary Type
+
+The library supports applying JSON patches to arbitrary types. Internally, the object is marshalled to JSON, then the patch is applied, and then the object is unmarshalled into its original type again. The usual limitations of JSON (un)marshalling (no cyclic structures, etc.) apply.
+
+```golang
+import "github.com/openmcp-project/controller-utils/pkg/jsonpatch"
+
+// mytype.Spec is of type MyTypeSpec as defined in the above example
+patch := jsonpatch.NewTyped[MyPatchedType](mytype.Spec.Patches)
+// obj and modified are of type MyPatchedType
+modified, err := patch.Apply(doc)
+```
+
+### Options
+
+The `Apply` method optionally takes some options which can be constructed from functions contained in the package:
+```golang
+modified, err := patch.Apply(doc, jsonpatch.Indent("  "))
+```
+
+The available options are:
+- `SupportNegativeIndices`
+- `AccumulatedCopySizeLimit`
+- `AllowMissingPathOnRemove`
+- `EnsurePathExistsOnAdd`
+- `EscapeHTML`
+- `Indent`
+
+The options are simply passed into the [library which is used internally](https://github.com/evanphx/json-patch).

go.mod

@@ -2,12 +2,16 @@ module github.com/openmcp-project/controller-utils
 
 go 1.24.2
 
+replace github.com/openmcp-project/controller-utils/api => ./api
+
 require (
+	github.com/evanphx/json-patch/v5 v5.9.11
 	github.com/go-logr/logr v1.4.3
 	github.com/go-logr/zapr v1.3.0
 	github.com/onsi/ginkgo v1.16.5
 	github.com/onsi/ginkgo/v2 v2.23.4
 	github.com/onsi/gomega v1.37.0
+	github.com/openmcp-project/controller-utils/api v0.0.0-00010101000000-000000000000
 	github.com/spf13/pflag v1.0.6
 	github.com/stretchr/testify v1.10.0
 	go.uber.org/zap v1.27.0
@@ -29,7 +33,7 @@ require (
 	github.com/davecgh/go-spew v1.1.2-0.20180830191138-d8f796af33cc // indirect
 	github.com/emicklei/go-restful/v3 v3.12.1 // indirect
 	github.com/evanphx/json-patch v4.12.0+incompatible // indirect
-	github.com/evanphx/json-patch/v5 v5.9.11 // indirect
+	github.com/fluxcd/pkg/apis/kustomize v1.10.0 // indirect
 	github.com/fsnotify/fsnotify v1.8.0 // indirect
 	github.com/fxamacker/cbor/v2 v2.7.0 // indirect
 	github.com/go-openapi/jsonpointer v0.21.0 // indirect

go.sum

@@ -14,6 +14,8 @@ github.com/evanphx/json-patch v4.12.0+incompatible h1:4onqiflcdA9EOZ4RxV643DvftH
 github.com/evanphx/json-patch v4.12.0+incompatible/go.mod h1:50XU6AFN0ol/bzJsmQLiYLvXMP4fmwYFNcr97nuDLSk=
 github.com/evanphx/json-patch/v5 v5.9.11 h1:/8HVnzMq13/3x9TPvjG08wUGqBTmZBsCWzjTM0wiaDU=
 github.com/evanphx/json-patch/v5 v5.9.11/go.mod h1:3j+LviiESTElxA4p3EMKAB9HXj3/XEtnUf6OZxqIQTM=
+github.com/fluxcd/pkg/apis/kustomize v1.10.0 h1:47EeSzkQvlQZdH92vHMe2lK2iR8aOSEJq95avw5idts=
+github.com/fluxcd/pkg/apis/kustomize v1.10.0/go.mod h1:UsqMV4sqNa1Yg0pmTsdkHRJr7bafBOENIJoAN+3ezaQ=
 github.com/fsnotify/fsnotify v1.4.7/go.mod h1:jwhsz4b93w/PPRr/qN1Yymfu8t87LnFCMoQvtojpjFo=
 github.com/fsnotify/fsnotify v1.4.9/go.mod h1:znqG4EE+3YCdAaPaxE2ZRY/06pZUdp0tY4IgpuI1SZQ=
 github.com/fsnotify/fsnotify v1.8.0 h1:dAwr6QBTBZIkG8roQaJjGof0pp0EeF+tNV7YBP3F/8M=