fix: Logging to stdout in Cloud Run creates a JSON object as "message" (#1305)

losalex · web-flow · commit cb5f424d1d5a · 2022-07-11T13:04:53.000-07:00
* fix: Logging to stdout in Cloud Run creates a JSON object as "message"

* Add test

* Add comments to code

* Add more tests to cover different data types
diff --git a/src/entry.ts b/src/entry.ts
@@ -86,6 +86,8 @@ export interface StructuredJson {
   // Properties not supported by all agents (e.g. Cloud Run, Functions)
   logName?: string;
   resource?: object;
+  // Properties to be stored in jsonPayload when running in serverless (e.g. Cloud Run , Functions)
+  [key: string]: unknown;
 }
 
 export interface ToJsonOptions {
@@ -202,7 +204,7 @@ class Entry {
   toJSON(options: ToJsonOptions = {}, projectId = '') {
     const entry: EntryJson = extend(true, {}, this.metadata) as {} as EntryJson;
     // Format log message
-    if (Object.prototype.toString.call(this.data) === '[object Object]') {
+    if (this.isObject(this.data)) {
       entry.jsonPayload = objToStruct(this.data, {
         removeCircular: !!options.removeCircular,
         stringify: true,
@@ -243,7 +245,7 @@ class Entry {
    * Serialize an entry to a standard format for any transports, e.g. agents.
    * Read more: https://cloud.google.com/logging/docs/structured-logging
    */
-  toStructuredJSON(projectId = '') {
+  toStructuredJSON(projectId = '', useMessageField = true) {
     const meta = this.metadata;
     // Mask out the keys that need to be renamed.
     /* eslint-disable @typescript-eslint/no-unused-vars */
@@ -260,7 +262,7 @@ class Entry {
       ...validKeys
     } = meta;
     /* eslint-enable @typescript-eslint/no-unused-vars */
-    const entry: StructuredJson = extend(true, {}, validKeys) as {};
+    let entry: StructuredJson = extend(true, {}, validKeys) as {};
     // Re-map keys names.
     entry[LABELS_KEY] = meta.labels
       ? Object.assign({}, meta.labels)
@@ -273,9 +275,29 @@ class Entry {
         ? meta.traceSampled
         : undefined;
     // Format log payload.
-    entry.message =
-      meta.textPayload || meta.jsonPayload || meta.protoPayload || undefined;
-    entry.message = this.data || entry.message;
+    const data =
+      this.data ||
+      meta.textPayload ||
+      meta.jsonPayload ||
+      meta.protoPayload ||
+      undefined;
+    if (useMessageField) {
+      /** If useMessageField is set, we add the payload to {@link StructuredJson#message} field.*/
+      entry.message = data;
+    } else {
+      /** useMessageField is false, we add the structured payload to {@link StructuredJson} key-value map.
+       * It could be especially useful for serverless environments like Cloud Run/Functions when stdout transport is used.
+       * Note that text still added to {@link StructuredJson#message} field for text payload since it does not have fields within. */
+      if (data !== undefined && data !== null) {
+        if (this.isObject(data)) {
+          entry = extend(true, {}, entry, data);
+        } else if (typeof data === 'string') {
+          entry.message = data;
+        } else {
+          entry.message = JSON.stringify(data);
+        }
+      }
+    }
     // Format timestamp
     if (meta.timestamp instanceof Date) {
       entry.timestamp = meta.timestamp.toISOString();
@@ -333,6 +355,15 @@ class Entry {
     }
     return serializedEntry;
   }
+
+  /**
+   * Determines whether `value` is a JavaScript object.
+   * @param value The value to be checked
+   * @returns true if `value` is a JavaScript object, false otherwise
+   */
+  private isObject(value: unknown): value is object {
+    return Object.prototype.toString.call(value) === '[object Object]';
+  }
 }
 
 /**
diff --git a/src/log-sync.ts b/src/log-sync.ts
@@ -30,6 +30,12 @@ import {
   WriteOptions,
 } from './utils/log-common';
 
+export interface LogSyncOptions {
+  // The flag indicating if "message" field should be used to store structured,
+  // non-text data inside jsonPayload field. By default this value is true
+  useMessageField?: boolean;
+}
+
 /**
  * A logSync is a named collection of entries in structured log format. In Cloud
  * Logging, structured logs refer to log entries that use the jsonPayload field
@@ -61,9 +67,16 @@ class LogSync implements LogSeverityFunctions {
   logging: Logging;
   name: string;
   transport: Writable;
+  useMessageField_: boolean;
 
   // not projectId, formattedname is expected
-  constructor(logging: Logging, name: string, transport?: Writable) {
+  constructor(
+    logging: Logging,
+    name: string,
+    transport?: Writable,
+    options?: LogSyncOptions
+  ) {
+    options = options || {};
     this.formattedName_ = formatLogName(logging.projectId, name);
     this.logging = logging;
     /**
@@ -73,6 +86,7 @@ class LogSync implements LogSeverityFunctions {
     this.name = this.formattedName_.split('/').pop()!;
     // Default to writing to stdout
     this.transport = transport || process.stdout;
+    this.useMessageField_ = options.useMessageField ?? true;
   }
 
   /**
@@ -417,7 +431,10 @@ class LogSync implements LogSeverityFunctions {
         if (!(entry instanceof Entry)) {
           entry = this.entry(entry);
         }
-        return entry.toStructuredJSON(this.logging.projectId);
+        return entry.toStructuredJSON(
+          this.logging.projectId,
+          this.useMessageField_
+        );
       });
       for (const entry of structuredEntries) {
         entry.logName = this.formattedName_;
diff --git a/test/entry.ts b/test/entry.ts
@@ -368,5 +368,28 @@ describe('Entry', () => {
       assert.strictEqual(json[entryTypes.SPAN_ID_KEY], '1');
       assert.strictEqual(json[entryTypes.TRACE_SAMPLED_KEY], false);
     });
+
+    it('should add message field for structured data', () => {
+      entry.data = {message: 'message', test: 'test'};
+      let json = entry.toStructuredJSON();
+      // eslint-disable-next-line @typescript-eslint/no-explicit-any
+      assert(((json.message as any).message = 'message'));
+      // eslint-disable-next-line @typescript-eslint/no-explicit-any
+      assert(((json.message as any).test = 'test'));
+      json = entry.toStructuredJSON(undefined, false);
+      assert((json.message = 'message'));
+      assert((json.test = 'test'));
+    });
+
+    it('should add message field only when needed', () => {
+      entry.data = 1;
+      let json = entry.toStructuredJSON();
+      assert((json.message = '1'));
+      json = entry.toStructuredJSON(undefined, false);
+      assert((json.message = '1'));
+      entry.data = 'test';
+      json = entry.toStructuredJSON(undefined, false);
+      assert((json.message = 'test'));
+    });
   });
 });
