Added loggers for App Engine flexible environment.

composer.json

@@ -26,6 +26,7 @@
     "google/auth": "0.7",
     "guzzlehttp/guzzle": "~5.2|~6.0",
     "guzzlehttp/psr7": "1.2.*",
+    "monolog/monolog": "~1",
     "psr/http-message": "1.0.*"
   },
   "require-dev": {

src/Logger/AppEngineFlexFormatter.php

@@ -0,0 +1,64 @@
+<?php
+/*
+ * Copyright 2016 Google Inc. All Rights Reserved.
+ *
+ * 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.
+ */
+namespace Google\Cloud\Logger;
+
+use Monolog\Formatter\LineFormatter;
+
+/**
+ * Class for formatting logs on App Engine flexible environment.
+ */
+class AppEngineFlexFormatter extends LineFormatter
+{
+    /**
+     * @param string $format The format of the message
+     * @param string $dateFormat The format of the timestamp
+     * @param bool $ignoreEmptyContextAndExtra
+     */
+    public function __construct($format = null, $dateFormat = null, $ignoreEmptyContextAndExtra = false)
+    {
+        parent::__construct($format, $dateFormat, true, $ignoreEmptyContextAndExtra);
+    }
+
+    /**
+     * Get the plain text message with LineFormatter's format method and add
+     * metadata including the trace id then return the json string.
+     *
+     * @param array $record A record to format
+     * @return mixed The formatted record
+     */
+    public function format(array $record)
+    {
+        $message = parent::format($record);
+        list($usec, $sec) = explode(" ", microtime());
+        $usec = (int)(((float)$usec)*1000000000);
+        $sec = (int)$sec;
+        $payload = [
+            'message' => $message,
+            'timestamp'=> ['seconds' => $sec,
+                           'nanos' => $usec],
+            'thread' => '',
+            'severity' => $record['level_name'],
+        ];
+        if (isset($_SERVER['HTTP_X_CLOUD_TRACE_CONTEXT'])) {
+            $payload['traceId'] = explode(
+                "/",
+                $_SERVER['HTTP_X_CLOUD_TRACE_CONTEXT']
+            )[0];
+        }
+        return "\n" . json_encode($payload);
+    }
+}

src/Logger/AppEngineFlexHandler.php

@@ -0,0 +1,63 @@
+<?php
+/*
+ * Copyright 2016 Google Inc. All Rights Reserved.
+ *
+ * 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.
+ */
+namespace Google\Cloud\Logger;
+
+use Monolog\Handler\StreamHandler;
+use Monolog\Logger;
+
+/**
+ * Class for logging on App Engine flexible environment.
+ */
+class AppEngineFlexHandler extends StreamHandler
+{
+    /**
+     * @param int $level The minimum logging level at which this handler will be triggered.
+     * @param Boolean $bubble Whether the messages that are handled can bubble up the stack or not.
+     * @param int|null $filePermission Optional file permissions (default (0640) are only for owner read/write).
+     * @param Boolean $useLocking Try to lock log file before doing any writes.
+     * @param resource|string|null $stream
+     */
+    public function __construct(
+        $level = Logger::INFO,
+        $bubble = true,
+        $filePermission = 0640,
+        $useLocking = false,
+        $stream = null
+    ) {
+        if ($stream === null) {
+            $pid = posix_getpid();
+            $stream = "file:///var/log/app_engine/app.$pid.json";
+        }
+        parent::__construct(
+            $stream,
+            $level,
+            $bubble,
+            $filePermission,
+            $useLocking
+        );
+    }
+
+    /**
+     * Get the default formatter.
+     *
+     * @return FormatterInterface
+     */
+    protected function getDefaultFormatter()
+    {
+        return new AppEngineFlexFormatter();
+    }
+}

tests/Logger/AppEngineFlexHandlerTest.php

@@ -0,0 +1,55 @@
+<?php
+/**
+ * Copyright 2016 Google 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.
+ */
+
+namespace Google\Cloud\Tests\Logger;
+
+use Google\Cloud\Logger\AppEngineFlexHandler;
+use Monolog\Logger;
+
+class AppEngineFlexHandlerTest extends \PHPUnit_Framework_TestCase
+{
+    private $path;
+    private $log;
+
+    public function setUp()
+    {
+        $dir = sys_get_temp_dir();
+        $this->path = tempnam($dir, "log");
+        $handler = new AppEngineFlexHandler(
+            Logger::DEBUG, true, 0640, false, $this->path
+        );
+        $this->log = new Logger('gcloud-test');
+        $this->log->pushHandler($handler);
+    }
+
+    public function tearDown()
+    {
+        unlink($this->path);
+    }
+
+    public function testOneLine()
+    {
+        $msg = 'Error message';
+        $this->log->addError($msg);
+        $log_text = file_get_contents($this->path);
+        $log_array = json_decode($log_text, true);
+        $this->assertContains($msg, $log_array['message']);
+        $this->assertInternalType('int', $log_array['timestamp']['seconds']);
+        $this->assertInternalType('int', $log_array['timestamp']['nanos']);
+        $this->assertEquals('ERROR', $log_array['severity']);
+    }
+}