Add Context.attributes(). (#24)

* Add `Context.attributes()`.

The main purpose is to reflect attributes defined by the CloudEvents spec
when the event source conforms to that spec.

Author: eamonnmcmanus

functions-framework-api/pom.xml

@@ -24,7 +24,7 @@
 
   <groupId>com.google.cloud.functions</groupId>
   <artifactId>functions-framework-api</artifactId>
-  <version>1.0.0-alpha-2-rc3-SNAPSHOT</version>
+  <version>1.0.0-alpha-2-rc4-SNAPSHOT</version>
 
   <properties>
     <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
@@ -65,6 +65,7 @@
       <plugin>
         <groupId>org.apache.maven.plugins</groupId>
         <artifactId>maven-source-plugin</artifactId>
+        <version>3.2.1</version>
         <executions>
           <execution>
             <id>attach-sources</id>
@@ -139,7 +140,7 @@
           <plugin>
             <groupId>org.apache.maven.plugins</groupId>
             <artifactId>maven-source-plugin</artifactId>
-            <version>3.0.1</version>
+            <version>3.2.1</version>
             <executions>
               <execution>
                 <id>attach-sources</id>

functions-framework-api/src/main/java/com/google/cloud/functions/Context.java

@@ -14,6 +14,9 @@
 
 package com.google.cloud.functions;
 
+import java.util.Collections;
+import java.util.Map;
+
 /** An interface for event function context. */
 public interface Context {
   /** Returns event ID. */
@@ -27,4 +30,20 @@ public interface Context {
 
   /** Returns event resource. */
   String resource();
+
+  /**
+   * Returns additional attributes from this event. For CloudEvents, the entries in this map will
+   * include the
+   * <a href="https://github.com/cloudevents/spec/blob/v1.0/spec.md#required-attributes">required
+   * attributes</a> and may include
+   * <a href="https://github.com/cloudevents/spec/blob/v1.0/spec.md#required-attributes">optional
+   * attributes</a> and
+   * <a href="https://github.com/cloudevents/spec/blob/v1.0/spec.md#extension-context-attributes">
+   * extension attributes</a>.
+   *
+   * <p>The map returned by this method may be empty but is never null.</p>
+   */
+  default Map<String, String> attributes() {
+    return Collections.emptyMap();
+  }
 }

invoker/core/src/main/java/com/google/cloud/functions/invoker/CloudFunctionsContext.java

@@ -20,6 +20,8 @@
 import com.google.gson.TypeAdapter;
 import java.lang.annotation.Retention;
 import java.lang.annotation.RetentionPolicy;
+import java.util.Collections;
+import java.util.Map;
 
 /** Event context (metadata) for events handled by Cloud Functions. */
 @AutoValue
@@ -28,24 +30,32 @@ abstract class CloudFunctionsContext implements Context {
   @Retention(RetentionPolicy.SOURCE)
   @interface Nullable {}
 
+  @Override
   @Nullable
   public abstract String eventId();
 
+  @Override
   @Nullable
   public abstract String timestamp();
 
+  @Override
   @Nullable
   public abstract String eventType();
 
+  @Override
   @Nullable
   public abstract String resource();
 
+  @Override
+  public abstract Map<String, String> attributes();
+
   public static TypeAdapter<CloudFunctionsContext> typeAdapter(Gson gson) {
     return new AutoValue_CloudFunctionsContext.GsonTypeAdapter(gson);
   }
 
   static Builder builder() {
-    return new AutoValue_CloudFunctionsContext.Builder();
+    return new AutoValue_CloudFunctionsContext.Builder()
+        .setAttributes(Collections.emptyMap());
   }
 
   @AutoValue.Builder
@@ -54,6 +64,8 @@ abstract static class Builder {
     abstract Builder setTimestamp(String x);
     abstract Builder setEventType(String x);
     abstract Builder setResource(String x);
+    abstract Builder setAttributes(Map<String, String> value);
+
     abstract CloudFunctionsContext build();
   }
 }

invoker/core/src/main/java/com/google/cloud/functions/invoker/NewBackgroundFunctionExecutor.java

@@ -133,11 +133,13 @@ private static Context contextFromCloudEvent(CloudEvent<AttributesImpl, ?> cloud
     // We don't have an obvious replacement for the Context.resource field, which with legacy events
     // corresponded to a value present for some proprietary Google event types.
     String resource = "{}";
+    Map<String, String> attributesMap = AttributesImpl.marshal(attributes);
     return CloudFunctionsContext.builder()
         .setEventId(attributes.getId())
         .setEventType(attributes.getType())
         .setResource(resource)
         .setTimestamp(timestampString)
+        .setAttributes(attributesMap)
         .build();
   }
 

invoker/core/src/test/java/com/google/cloud/functions/invoker/IntegrationTest.java

@@ -115,6 +115,18 @@ private static CloudEventImpl<Map<String, Object>> sampleCloudEvent(File snoopFi
         .build();
   }
 
+  private static JsonObject expectedCloudEventAttributes() {
+    JsonObject attributes = new JsonObject();
+    attributes.addProperty("datacontenttype", "application/json");
+    attributes.addProperty("specversion", "1.0");
+    attributes.addProperty("id", "B234-1234-1234");
+    attributes.addProperty("source", "/source");
+    attributes.addProperty("time", "2018-04-05T17:31:00Z");
+    attributes.addProperty("type", "com.example.someevent.new");
+    attributes.addProperty("dataschema", "/schema");
+    return attributes;
+  }
+
   private static int serverPort;
 
   /**
@@ -144,7 +156,7 @@ abstract static class TestCase {
 
     abstract Optional<String> expectedResponseText();
 
-    abstract Optional<String> expectedJsonString();
+    abstract Optional<JsonObject> expectedJson();
 
     abstract Optional<String> expectedContentType();
 
@@ -183,7 +195,7 @@ abstract static class Builder {
 
       abstract Builder setExpectedOutput(String x);
 
-      abstract Builder setExpectedJsonString(String x);
+      abstract Builder setExpectedJson(JsonObject x);
 
       abstract Builder setHttpContentType(String x);
 
@@ -319,7 +331,7 @@ public void background() throws Exception {
     TestCase testCase = TestCase.builder()
         .setRequestText(requestText)
         .setSnoopFile(snoopFile)
-        .setExpectedJsonString(requestText)
+        .setExpectedJson(new Gson().fromJson(requestText, JsonObject.class))
         .build();
     backgroundTest(fullTarget("BackgroundSnoop.snoop"), ImmutableList.of(testCase));
   }
@@ -337,24 +349,28 @@ public void newTypedBackground() throws Exception {
   private void newBackgroundTest(String target) throws Exception {
     File snoopFile = snoopFile();
     String gcfRequestText = sampleLegacyEvent(snoopFile);
+    JsonObject expectedJson = new Gson().fromJson(gcfRequestText, JsonObject.class);
+    // We don't currently put anything in the attributes() map for legacy events.
+    expectedJson.add("attributes", new JsonObject());
     TestCase gcfTestCase = TestCase.builder()
         .setRequestText(gcfRequestText)
         .setSnoopFile(snoopFile)
-        .setExpectedJsonString(gcfRequestText)
+        .setExpectedJson(expectedJson)
         .build();
 
     // A CloudEvent using the "structured content mode", where both the metadata and the payload
     // are in the body of the HTTP request.
     String cloudEventRequestText = Json.encode(sampleCloudEvent(snoopFile));
     // For CloudEvents, we don't currently populate Context#getResource with anything interesting,
     // so we excise that from the expected text we would have with legacy events.
-    String cloudEventExpectedJsonString =
-        gcfRequestText.replaceAll("\"resource\":\\s*\\{[^}]*\\}", "\"resource\":{}");
+    JsonObject cloudEventExpectedJson = new Gson().fromJson(gcfRequestText, JsonObject.class);
+    cloudEventExpectedJson.getAsJsonObject("context").add("resource", new JsonObject());
+    cloudEventExpectedJson.add("attributes", expectedCloudEventAttributes());
     TestCase cloudEventsStructuredTestCase = TestCase.builder()
         .setSnoopFile(snoopFile)
         .setRequestText(cloudEventRequestText)
         .setHttpContentType("application/cloudevents+json; charset=utf-8")
-        .setExpectedJsonString(cloudEventExpectedJsonString)
+        .setExpectedJson(cloudEventExpectedJson)
         .build();
 
     // A CloudEvent using the "binary content mode", where the metadata is in HTTP headers and the
@@ -367,7 +383,7 @@ private void newBackgroundTest(String target) throws Exception {
         .setRequestText(wire.getPayload().get())
         .setHttpContentType("application/json")
         .setHttpHeaders(ImmutableMap.copyOf(wire.getHeaders()))
-        .setExpectedJsonString(cloudEventExpectedJsonString)
+        .setExpectedJson(cloudEventExpectedJson)
         .build();
     // TODO(emcmanus): Update the Content-Type to "application/json; charset=utf-8" when
     // https://github.com/cloudevents/sdk-java/issues/89 has been fixed.
@@ -458,19 +474,19 @@ private void backgroundTest(String functionTarget, List<TestCase> testCases) thr
       String snooped = new String(Files.readAllBytes(snoopFile.toPath()), StandardCharsets.UTF_8);
       Gson gson = new Gson();
       JsonObject snoopedJson = gson.fromJson(snooped, JsonObject.class);
-      String expectedJsonString = testCase.expectedJsonString().get();
-      JsonObject expectedJson = gson.fromJson(expectedJsonString, JsonObject.class);
+      JsonObject expectedJson = testCase.expectedJson().get();
       expect.withMessage("Testing %s with %s", functionTarget, testCase)
           .that(snoopedJson).isEqualTo(expectedJson);
     }
   }
 
-  private void checkSnoopFile(File snoopFile, String expectedJsonString) throws IOException {
+  private void checkSnoopFile(TestCase testCase) throws IOException {
+    File snoopFile = testCase.snoopFile().get();
+    JsonObject expectedJson = testCase.expectedJson().get();
     String snooped = new String(Files.readAllBytes(snoopFile.toPath()), StandardCharsets.UTF_8);
     Gson gson = new Gson();
     JsonObject snoopedJson = gson.fromJson(snooped, JsonObject.class);
-    JsonObject expectedJson = gson.fromJson(expectedJsonString, JsonObject.class);
-    expect.that(snoopedJson).isEqualTo(expectedJson);
+    expect.withMessage("Testing with %s", testCase).that(snoopedJson).isEqualTo(expectedJson);
   }
 
   private void testHttpFunction(String target, List<TestCase> testCases) throws Exception {
@@ -518,7 +534,7 @@ private void testFunction(
         testCase.expectedContentType()
             .ifPresent(type -> expect.that(response.getMediaType()).isEqualTo(type));
         if (testCase.snoopFile().isPresent()) {
-          checkSnoopFile(testCase.snoopFile().get(), testCase.expectedJsonString().get());
+          checkSnoopFile(testCase);
         }
         testCase.expectedOutput()
             .ifPresent(output -> expect.that(serverProcess.output().toString()).contains(output));

invoker/core/src/test/java/com/google/cloud/functions/invoker/testfunctions/NewBackgroundSnoop.java

@@ -34,6 +34,7 @@ public void accept(String json, Context context) {
     JsonObject contextAndPayloadJson = new JsonObject();
     contextAndPayloadJson.add("data", jsonObject);
     contextAndPayloadJson.add("context", contextJson);
+    contextAndPayloadJson.add("attributes", gson.toJsonTree(context.attributes()));
     try (FileWriter fileWriter = new FileWriter(targetFile);
         PrintWriter writer = new PrintWriter(fileWriter)) {
       writer.println(contextAndPayloadJson);

invoker/core/src/test/java/com/google/cloud/functions/invoker/testfunctions/NewTypedBackgroundSnoop.java

@@ -40,6 +40,7 @@ public void accept(Payload payload, Context context) {
     JsonObject contextAndPayloadJson = new JsonObject();
     contextAndPayloadJson.add("data", gson.toJsonTree(payload));
     contextAndPayloadJson.add("context", contextJson);
+    contextAndPayloadJson.add("attributes", gson.toJsonTree(context.attributes()));
     try (FileWriter fileWriter = new FileWriter(targetFile);
         PrintWriter writer = new PrintWriter(fileWriter)) {
       writer.println(contextAndPayloadJson);

invoker/pom.xml

@@ -42,7 +42,7 @@
       <dependency>
         <groupId>com.google.cloud.functions</groupId>
         <artifactId>functions-framework-api</artifactId>
-        <version>1.0.0-alpha-2-rc3</version>
+        <version>1.0.0-alpha-2-rc4-SNAPSHOT</version>
       </dependency>
     </dependencies>
   </dependencyManagement>