Add CEL function to parse YAML

Added a CEL function named parseYAML that can parse an YAML string into a map of strings to dynamic values Syntax: <string>.parseYAML() -> map<string, dyn>
tektoncd · Jun 26, 2020 · 5348837 · 5348837
1 parent fa3a902
commit 5348837
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Showing 4 changed files with 70 additions and 3 deletions.
diff --git a/docs/cel_expressions.md b/docs/cel_expressions.md
@@ -276,6 +276,20 @@ interceptor.
      <pre>'{"testing":"value"}'.parseJSON().testing == "value"</pre>
     </td>
   </tr>
+  <tr>
+    <th>
+     parseYAML()
+    </th>
+    <td>
+     <pre>&lt;string&gt;.parseYAML() -> map&lt;string, dyn&gt;</pre>
+    </td>
+    <td>
+     This parses a string that contains a YAML body into a map which which can be subsequently used in other expressions.
+    </td>
+    <td>
+     <pre>'key1: value1\nkey2: value2\n'.parseYAML().key1 == "value"</pre>
+    </td>
+  </tr>
   <tr>
     <th>
      parseURL()

diff --git a/go.mod b/go.mod
@@ -35,7 +35,7 @@ require (
 	k8s.io/utils v0.0.0-20200324210504-a9aa75ae1b89 // indirect
 	knative.dev/caching v0.0.0-20200228235451-13d271455c74
 	knative.dev/pkg v0.0.0-20200207155214-fef852970f43
-	sigs.k8s.io/yaml v1.2.0 // indirect
+	sigs.k8s.io/yaml v1.2.0
 )
 
 // Knative deps (release-0.12)

diff --git a/pkg/interceptors/cel/cel_test.go b/pkg/interceptors/cel/cel_test.go
@@ -329,6 +329,7 @@ func TestExpressionEvaluation(t *testing.T) {
 		},
 		"b64value":  "ZXhhbXBsZQ==",
 		"json_body": `{"testing": "value"}`,
+		"yaml_body": "key1: value1\nkey2: value2\nkey3: value3\n",
 		"testURL":   "https://user:password@site.example.com/path/to?query=search#first",
 		"multiURL":  "https://user:password@site.example.com/path/to?query=search&query=results",
 	}
@@ -426,6 +427,11 @@ func TestExpressionEvaluation(t *testing.T) {
 			expr: "body.json_body.parseJSON().testing == 'value'",
 			want: types.Bool(true),
 		},
+		{
+			name: "parse YAML body in a string",
+			expr: "body.yaml_body.parseYAML().key1 == 'value1'",
+			want: types.Bool(true),
+		},
 		{
 			name: "parse URL",
 			expr: "body.testURL.parseURL().path == '/path/to'",
@@ -477,8 +483,10 @@ func TestExpressionEvaluation(t *testing.T) {
 func TestExpressionEvaluation_Error(t *testing.T) {
 	testSHA := "ec26c3e57ca3a959ca5aad62de7213c562f8c821"
 	jsonMap := map[string]interface{}{
-		"value": "testing",
-		"sha":   testSHA,
+		"value":        "testing",
+		"sha":          testSHA,
+		"valid_yaml":   "key1: value1\nkey2: value2\n",
+		"invalid_yaml": "key1: value1key2: value2\n",
 		"pull_request": map[string]interface{}{
 			"commits": []string{},
 		},
@@ -547,6 +555,21 @@ func TestExpressionEvaluation_Error(t *testing.T) {
 			expr: "body.pull_request.parseJSON().test == 'test'",
 			want: "unexpected type 'map' passed to parseJSON",
 		},
+		{
+			name: "parseYAML decoding non-string",
+			expr: "body.pull_request.parseYAML().key1 == 'value1'",
+			want: "unexpected type 'map' passed to parseYAML",
+		},
+		{
+			name: "unknown key",
+			expr: "body.valid_yaml.parseYAML().key3 == 'value3'",
+			want: "no such key: key3",
+		},
+		{
+			name: "invalid YAML body",
+			expr: "body.invalid_yaml.parseYAML().key1 == 'value1'",
+			want: "failed to decode 'key1: value1key2: value2\n' in parseYAML:",
+		},
 	}
 	for _, tt := range tests {
 		t.Run(tt.name, func(rt *testing.T) {

diff --git a/pkg/interceptors/cel/triggers.go b/pkg/interceptors/cel/triggers.go
@@ -31,6 +31,7 @@ import (
 	"github.com/google/cel-go/interpreter/functions"
 	"github.com/tektoncd/triggers/pkg/interceptors"
 	"k8s.io/client-go/kubernetes"
+	"sigs.k8s.io/yaml"
 
 	triggersv1 "github.com/tektoncd/triggers/pkg/apis/triggers/v1alpha1"
 	exprpb "google.golang.org/genproto/googleapis/api/expr/v1alpha1"
@@ -137,6 +138,16 @@ import (
 // Examples:
 //
 //     'https://example.com/testing'.parseURL().host == 'example.com'
+//
+// parseYAML
+//
+// Parses a YAML string into a map of strings to dynamic values
+//
+// 		<string>.parseYAML() -> map<string, dyn>
+//
+// Examples:
+//
+// 		body.field.parseYAML().item
 
 // Triggers creates and returns a new cel.Lib with the triggers extensions.
 func Triggers(request *http.Request, ns string, k kubernetes.Interface) cel.EnvOption {
@@ -171,6 +182,9 @@ func (triggersLib) CompileOptions() []cel.EnvOption {
 			decls.NewFunction("parseJSON",
 				decls.NewInstanceOverload("parseJSON_string",
 					[]*exprpb.Type{decls.String}, mapStrDyn)),
+			decls.NewFunction("parseYAML",
+				decls.NewInstanceOverload("parseYAML_string",
+					[]*exprpb.Type{decls.String}, mapStrDyn)),
 			decls.NewFunction("parseURL",
 				decls.NewInstanceOverload("parseURL_string",
 					[]*exprpb.Type{decls.String}, mapStrDyn)),
@@ -197,6 +211,9 @@ func (t triggersLib) ProgramOptions() []cel.ProgramOption {
 			&functions.Overload{
 				Operator: "parseJSON",
 				Unary:    parseJSONString},
+			&functions.Overload{
+				Operator: "parseYAML",
+				Unary:    parseYAMLString},
 			&functions.Overload{
 				Operator: "parseURL",
 				Unary:    parseURLString},
@@ -322,6 +339,19 @@ func parseJSONString(val ref.Val) ref.Val {
 	return types.NewDynamicMap(types.NewRegistry(), decodedVal)
 }
 
+func parseYAMLString(val ref.Val) ref.Val {
+	str, ok := val.(types.String)
+	if !ok {
+		return types.ValOrErr(str, "unexpected type '%v' passed to parseYAML", val.Type())
+	}
+	decodedVal := map[string]interface{}{}
+	err := yaml.Unmarshal([]byte(str), &decodedVal)
+	if err != nil {
+		return types.NewErr("failed to decode '%v' in parseYAML: %w", str, err)
+	}
+	return types.NewDynamicMap(types.NewRegistry(), decodedVal)
+}
+
 func parseURLString(val ref.Val) ref.Val {
 	str, ok := val.(types.String)
 	if !ok {