feat(SpelHelpers): Support parsing multi-document yaml strings (#3973)

* feat(SpelHelpers): Support parsing multi-document yaml strings

* Amend review sugestions

* Fix naming

orca-core/src/main/java/com/netflix/spinnaker/orca/pipeline/expressions/functions/UrlExpressionFunctionProvider.java

@@ -27,10 +27,7 @@
 import java.io.ByteArrayInputStream;
 import java.io.IOException;
 import java.net.URL;
-import java.util.HashMap;
-import java.util.List;
-import java.util.Map;
-import java.util.Properties;
+import java.util.*;
 import java.util.concurrent.atomic.AtomicReference;
 import org.jetbrains.annotations.NotNull;
 import org.jetbrains.annotations.Nullable;
@@ -80,7 +77,11 @@ public Functions getFunctions() {
             new FunctionParameter(String.class, "value", "A String containing JSON text")),
         new FunctionDefinition(
             "readYaml",
-            "Parses YAML from a string to be accessed, parsed JSON can be accessed as an object",
+            "Parses YAML from a string to be accessed, parsed YAML can be accessed as an object",
+            new FunctionParameter(String.class, "value", "A String containing YAML text")),
+        new FunctionDefinition(
+            "readAllYaml",
+            "Parses multi-doc YAML from a string to be accessed, list of parsed YAML can be accessed as objects",
             new FunctionParameter(String.class, "value", "A String containing YAML text")));
   }
 
@@ -136,6 +137,26 @@ public static Object readYaml(String text) {
     }
   }
 
+  /**
+   * Attempts to read a multi-doc yaml from a text String. Will throw a parsing exception on bad
+   * yaml
+   *
+   * @param text text to read as yaml
+   * @return a list of the object representations of the yaml text
+   */
+  public static Object readAllYaml(String text) {
+    try {
+      List<Object> yamlDocs = new ArrayList<>();
+      Iterable<Object> iterable = new Yaml().loadAll(text);
+      for (Object o : iterable) {
+        yamlDocs.add(o);
+      }
+      return yamlDocs;
+    } catch (Exception e) {
+      throw new SpelHelperFunctionException(format("#readAllYaml(%s) failed", text), e);
+    }
+  }
+
   /**
    * Reads a properties file stored at a url
    *

orca-core/src/test/groovy/com/netflix/spinnaker/orca/pipeline/expressions/functions/UrlExpressionFunctionProviderSpec.groovy

@@ -0,0 +1,55 @@
+/*
+ * Copyright 2020 Adevinta, Inc.
+ *
+ * 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 com.netflix.spinnaker.orca.pipeline.expressions.functions
+
+import com.netflix.spinnaker.kork.expressions.SpelHelperFunctionException
+import spock.lang.Specification
+import spock.lang.Unroll
+
+class UrlExpressionFunctionProviderSpec extends Specification {
+
+  @Unroll
+  def "test readYaml"() {
+    expect:
+    UrlExpressionFunctionProvider.readYaml(currentYaml) == expectedYaml
+
+    where:
+    currentYaml               || expectedYaml
+    "a: 1\nb: 2\n"            || [a: 1, b: 2]
+    "---\na: 1\nb: 2\n"       || [a: 1, b: 2]
+  }
+
+  def "readYaml returns exception on multi-doc YAML"() {
+    when:
+    UrlExpressionFunctionProvider.readYaml("a: 1\nb: 2\n---\nc: 3\n")
+
+    then:
+      thrown(SpelHelperFunctionException)
+  }
+
+  @Unroll
+  def "test readAllYaml"() {
+    expect:
+    UrlExpressionFunctionProvider.readAllYaml(currentYaml) == expectedYaml
+
+    where:
+    currentYaml               || expectedYaml
+    "a: 1\nb: 2\n"            || [[a: 1, b: 2]]
+    "---\na: 1\nb: 2\n"       || [[a: 1, b: 2]]
+    "a: 1\nb: 2\n---\nc: 3\n" || [[a: 1, b: 2],[c: 3]]
+  }
+}