add support for shallow substitution (#11058)

* add support for shallow substitution

Signed-off-by: Jim Bugwadia <jim@nirmata.com>

* linter issue

Signed-off-by: Jim Bugwadia <jim@nirmata.com>

* exclude EphemeralReport and ClusterEphemeralReport

Signed-off-by: Jim Bugwadia <jim@nirmata.com>

* update codegen

Signed-off-by: Jim Bugwadia <jim@nirmata.com>

---------

Signed-off-by: Jim Bugwadia <jim@nirmata.com>
Co-authored-by: Charles-Edouard Brétéché <charles.edouard@nirmata.com>

charts/kyverno/values.yaml

@@ -224,6 +224,8 @@ config:
     - '[Pod/binding,*,*]'
     - '[ReplicaSet,*,*]'
     - '[ReplicaSet/*,*,*]'
+    - '[EphemeralReport,*,*]'
+    - '[ClusterEphemeralReport,*,*]'
     # exclude resources from the chart
     - '[ClusterRole,*,{{ template "kyverno.admission-controller.roleName" . }}]'
     - '[ClusterRole,*,{{ template "kyverno.admission-controller.roleName" . }}:core]'

config/install-latest-testing.yaml

@@ -86,6 +86,8 @@ data:
     [Pod/binding,*,*]
     [ReplicaSet,*,*]
     [ReplicaSet/*,*,*]
+    [EphemeralReport,*,*]
+    [ClusterEphemeralReport,*,*]
     [ClusterRole,*,kyverno:admission-controller]
     [ClusterRole,*,kyverno:admission-controller:core]
     [ClusterRole,*,kyverno:admission-controller:additional]

pkg/engine/variables/regex/vars.go

@@ -3,10 +3,9 @@ package regex
 import "regexp"
 
 var (
+	// RegexVariables is the Regex for '{{...}}' at the beginning of the string, and 'x{{...}}' where 'x' is not '\'
 	RegexVariables = regexp.MustCompile(`(^|[^\\])(\{\{(?:\{[^{}]*\}|[^{}])*\}\})`)
 
-	RegexEscpVariables = regexp.MustCompile(`\\\{\{(\{[^{}]*\}|[^{}])*\}\}`)
-
 	// RegexReferences is the Regex for '$(...)' at the beginning of the string, and 'x$(...)' where 'x' is not '\'
 	RegexReferences = regexp.MustCompile(`^\$\(.[^\ ]*\)|[^\\]\$\(.[^\ ]*\)`)
 
@@ -16,6 +15,4 @@ var (
 	RegexVariableInit = regexp.MustCompile(`^\{\{(\{[^{}]*\}|[^{}])*\}\}`)
 
 	RegexElementIndex = regexp.MustCompile(`{{\s*elementIndex\d*\s*}}`)
-
-	RegexVariableKey = regexp.MustCompile(`\{{(.*?)\}}`)
 )

pkg/engine/variables/vars.go

@@ -222,7 +222,7 @@ func validateElementInForEach() jsonUtils.Action {
 				v = v[1:]
 			}
 
-			variable := replaceBracesAndTrimSpaces(v)
+			variable, _ := replaceBracesAndTrimSpaces(v)
 			isElementVar := strings.HasPrefix(variable, "element") || variable == "elementIndex"
 			if isElementVar && !strings.Contains(data.Path, "/foreach/") {
 				return nil, fmt.Errorf("variable '%v' present outside of foreach at path %s", variable, data.Path)
@@ -308,7 +308,7 @@ func DefaultVariableResolver(ctx context.EvalInterface, variable string) (interf
 	return ctx.Query(variable)
 }
 
-func substituteVariablesIfAny(log logr.Logger, ctx context.EvalInterface, vr VariableResolver) jsonUtils.Action {
+func substituteVariablesIfAny(log logr.Logger, ctx context.EvalInterface, lookupVar VariableResolver) jsonUtils.Action {
 	isDeleteRequest := isDeleteRequest(ctx)
 	return jsonUtils.OnlyForLeafsAndKeys(func(data *jsonUtils.ActionData) (interface{}, error) {
 		value, ok := data.Element.(string)
@@ -319,16 +319,16 @@ func substituteVariablesIfAny(log logr.Logger, ctx context.EvalInterface, vr Var
 		vars := regex.RegexVariables.FindAllString(value, -1)
 		for len(vars) > 0 {
 			originalPattern := value
+			shallowSubstitution := false
+			var variable string
 			for _, v := range vars {
 				initial := len(regex.RegexVariableInit.FindAllString(v, -1)) > 0
 				old := v
-
 				if !initial {
 					v = v[1:]
 				}
 
-				variable := replaceBracesAndTrimSpaces(v)
-
+				variable, shallowSubstitution = replaceBracesAndTrimSpaces(v)
 				if variable == "@" {
 					pathPrefix := "target"
 					if _, err := ctx.Query("target"); err != nil {
@@ -339,7 +339,6 @@ func substituteVariablesIfAny(log logr.Logger, ctx context.EvalInterface, vr Var
 					// Skip 2 elements (e.g. mutate.overlay | validate.pattern) plus "foreach" if it is part of the pointer.
 					// Prefix the pointer with pathPrefix.
 					val := jsonpointer.ParsePath(data.Path).SkipPast("foreach").SkipN(2).Prepend(strings.Split(pathPrefix, ".")...).JMESPath()
-
 					variable = strings.Replace(variable, "@", val, -1)
 				}
 
@@ -347,7 +346,7 @@ func substituteVariablesIfAny(log logr.Logger, ctx context.EvalInterface, vr Var
 					variable = strings.ReplaceAll(variable, "request.object", "request.oldObject")
 				}
 
-				substitutedVar, err := vr(ctx, variable)
+				substitutedVar, err := lookupVar(ctx, variable)
 				if err != nil {
 					switch err.(type) {
 					case context.InvalidVariableError, gojmespath.NotFoundError:
@@ -368,6 +367,10 @@ func substituteVariablesIfAny(log logr.Logger, ctx context.EvalInterface, vr Var
 					prefix = string(old[0])
 				}
 
+				if shallowSubstitution {
+					substitutedVar = strings.ReplaceAll(substitutedVar.(string), "{{", "\\{{")
+				}
+
 				if value, err = substituteVarInPattern(prefix, value, v, substitutedVar); err != nil {
 					return nil, fmt.Errorf("failed to resolve %v at path %s: %s", variable, data.Path, err.Error())
 				}
@@ -375,14 +378,16 @@ func substituteVariablesIfAny(log logr.Logger, ctx context.EvalInterface, vr Var
 				continue
 			}
 
-			// check for nested variables in strings
-			vars = regex.RegexVariables.FindAllString(value, -1)
-		}
-
-		for _, v := range regex.RegexEscpVariables.FindAllString(value, -1) {
-			value = strings.Replace(value, v, v[1:], -1)
+			if shallowSubstitution {
+				vars = []string{}
+			} else {
+				// check for nested variables in strings
+				vars = regex.RegexVariables.FindAllString(value, -1)
+			}
 		}
 
+		// Unescape escaped braces
+		value = strings.ReplaceAll(value, "\\{{", "{{")
 		return value, nil
 	})
 }
@@ -418,11 +423,16 @@ func substituteVarInPattern(prefix, pattern, variable string, value interface{})
 	return strings.Replace(pattern, variable, stringToSubstitute, 1), nil
 }
 
-func replaceBracesAndTrimSpaces(v string) string {
-	variable := strings.ReplaceAll(v, "{{", "")
+func replaceBracesAndTrimSpaces(v string) (variable string, isShallow bool) {
+	variable = strings.ReplaceAll(v, "{{", "")
 	variable = strings.ReplaceAll(variable, "}}", "")
 	variable = strings.TrimSpace(variable)
-	return variable
+	if strings.HasPrefix(variable, "-") {
+		variable = strings.TrimSpace(variable[1:])
+		return variable, true
+	}
+
+	return variable, false
 }
 
 func resolveReference(fullDocument interface{}, reference, absolutePath string) (interface{}, error) {

pkg/engine/variables/vars_test.go

@@ -544,6 +544,50 @@ func Test_SubstituteRecursive(t *testing.T) {
 	}
 }
 
+func Test_SubstituteShallow(t *testing.T) {
+	ctx := context.NewContext(jp)
+	data := map[string]interface{}{
+		"variableWithVariables": "{{ DO_NOT_SUBSTITUTE_ME {{OR_ME}} }}",
+		"foo":                   "bar",
+		"foo2":                  "bar2",
+		"variablesNested":       "{{foo2}}",
+	}
+
+	assert.NilError(t, context.AddJSONObject(ctx, data))
+
+	patternRaw := []byte(`"{{- variableWithVariables }} {{foo}} {{variablesNested}}"`)
+	action := substituteVariablesIfAny(logr.Discard(), ctx, DefaultVariableResolver)
+	results, err := action(&ju.ActionData{
+		Document: nil,
+		Element:  string(patternRaw),
+		Path:     "/",
+	})
+
+	assert.NilError(t, err)
+	assert.Equal(t, results.(string), "\"{{ DO_NOT_SUBSTITUTE_ME {{OR_ME}} }} bar bar2\"")
+
+	patternRaw = []byte(`"{{foo}} {{- variableWithVariables }} {{variablesNested}}"`)
+	action = substituteVariablesIfAny(logr.Discard(), ctx, DefaultVariableResolver)
+	results, err = action(&ju.ActionData{
+		Document: nil,
+		Element:  string(patternRaw),
+		Path:     "/",
+	})
+
+	assert.NilError(t, err)
+	assert.Equal(t, results.(string), "\"bar {{ DO_NOT_SUBSTITUTE_ME {{OR_ME}} }} bar2\"")
+
+	patternRaw = []byte(`"{{- variableWithVariables {{foo}} {{variablesNested}} }}"`)
+	action = substituteVariablesIfAny(logr.Discard(), ctx, DefaultVariableResolver)
+	_, err = action(&ju.ActionData{
+		Document: nil,
+		Element:  string(patternRaw),
+		Path:     "/",
+	})
+
+	assert.ErrorContains(t, err, "failed to resolve variableWithVariables bar bar2")
+}
+
 func Test_policyContextValidation(t *testing.T) {
 	policyContext := []byte(`
 	{