diff --git a/config/config.sample.php b/config/config.sample.php
index 45aaf6a107..9a40f82252 100644
--- a/config/config.sample.php
+++ b/config/config.sample.php
@@ -486,6 +486,27 @@ $CONFIG = array(
  */
 'loglevel' => 2,
 
+/**
+ * Log condition for log level increase based on conditions. Once one of these
+ * conditions is met, the required log level is set to debug. This allows to
+ * debug specific requests, users or apps
+ *
+ * Supported conditions:
+ *  - ``shared_secret``: if a request parameter with the name `log_secret` is set to
+ *                this value the condition is met
+ *  - ``users``:  if the current request is done by one of the specified users,
+ *                this condition is met
+ *  - ``apps``:   if the log message is invoked by one of the specified apps,
+ *                this condition is met
+ *
+ * Defaults to an empty array.
+ */
+'log.condition' => [
+	'shared_secret' => '57b58edb6637fe3059b3595cf9c41b9',
+	'users' => ['sample-user'],
+	'apps' => ['files'],
+],
+
 /**
  * This uses PHP.date formatting; see http://php.net/manual/en/function.date.php
  */
diff --git a/lib/private/log.php b/lib/private/log.php
index 56f36787e0..840713b2ed 100644
--- a/lib/private/log.php
+++ b/lib/private/log.php
@@ -28,6 +28,7 @@
 namespace OC;
 
 use \OCP\ILogger;
+use OCP\Security\StringUtils;
 
 /**
  * logging utilities
@@ -41,15 +42,29 @@ use \OCP\ILogger;
 
 class Log implements ILogger {
 
+	/** @var string */
 	private $logger;
+	/** @var SystemConfig */
+	private $config;
+
+	/** @var boolean|null cache the result of the log condition check for the request */
+	private $logConditionSatisfied = null;
 
 	/**
 	 * @param string $logger The logger that should be used
+	 * @param SystemConfig $config the system config object
 	 */
-	public function __construct($logger=null) {
+	public function __construct($logger=null, SystemConfig $config=null) {
+		// FIXME: Add this for backwards compatibility, should be fixed at some point probably
+		if($config === null) {
+			$config = \OC::$server->getSystemConfig();
+		}
+
+		$this->config = $config;
+
 		// FIXME: Add this for backwards compatibility, should be fixed at some point probably
 		if($logger === null) {
-			$this->logger = 'OC_Log_'.ucfirst(\OC_Config::getValue('log_type', 'owncloud'));
+			$this->logger = 'OC_Log_'.ucfirst($this->config->getValue('log_type', 'owncloud'));
 			call_user_func(array($this->logger, 'init'));
 		} else {
 			$this->logger = $logger;
@@ -158,8 +173,22 @@ class Log implements ILogger {
 	 * @param array $context
 	 */
 	public function log($level, $message, array $context = array()) {
+		$minLevel = min($this->config->getValue('loglevel', \OC_Log::WARN), \OC_Log::ERROR);
+		$logCondition = $this->config->getValue('log.condition', []);
+
 		if (isset($context['app'])) {
 			$app = $context['app'];
+
+			/**
+			 * check log condition based on the context of each log message
+			 * once this is met -> change the required log level to debug
+			 */
+			if(!empty($logCondition)
+				&& isset($logCondition['apps'])
+				&& in_array($app, $logCondition['apps'], true)) {
+				$minLevel = \OC_Log::DEBUG;
+			}
+
 		} else {
 			$app = 'no app in context';
 		}
@@ -172,7 +201,45 @@ class Log implements ILogger {
 		// interpolate replacement values into the message and return
 		$message = strtr($message, $replace);
 
-		$logger = $this->logger;
-		call_user_func(array($logger, 'write'), $app, $message, $level);
+		/**
+		 * check for a special log condition - this enables an increased log on
+		 * a per request/user base
+		 */
+		if($this->logConditionSatisfied === null) {
+			// default to false to just process this once per request
+			$this->logConditionSatisfied = false;
+			if(!empty($logCondition)) {
+
+				// check for secret token in the request
+				if(isset($logCondition['shared_secret'])) {
+					$request = \OC::$server->getRequest();
+
+					// if token is found in the request change set the log condition to satisfied
+					if($request && StringUtils::equals($request->getParam('log_secret'), $logCondition['shared_secret'])) {
+						$this->logConditionSatisfied = true;
+					}
+				}
+
+				// check for user
+				if(isset($logCondition['users'])) {
+					$user = \OC::$server->getUserSession()->getUser();
+
+					// if the user matches set the log condition to satisfied
+					if($user !== null && in_array($user->getUID(), $logCondition['users'], true)) {
+						$this->logConditionSatisfied = true;
+					}
+				}
+			}
+		}
+
+		// if log condition is satisfied change the required log level to DEBUG
+		if($this->logConditionSatisfied) {
+			$minLevel = \OC_Log::DEBUG;
+		}
+
+		if ($level >= $minLevel) {
+			$logger = $this->logger;
+			call_user_func(array($logger, 'write'), $app, $message, $level);
+		}
 	}
 }
diff --git a/lib/private/log/errorlog.php b/lib/private/log/errorlog.php
index 007ab30772..ad3605136d 100644
--- a/lib/private/log/errorlog.php
+++ b/lib/private/log/errorlog.php
@@ -39,10 +39,7 @@ class OC_Log_Errorlog {
 	 * @param int $level
 	 */
 	public static function write($app, $message, $level) {
-		$minLevel = min(OC_Config::getValue("loglevel", OC_Log::WARN), OC_Log::ERROR);
-		if ($level >= $minLevel) {
-			error_log('[owncloud]['.$app.'] '.$message);
-		}
+		error_log('[owncloud]['.$app.']['.$level.'] '.$message);
 	}
 }
 
diff --git a/lib/private/log/owncloud.php b/lib/private/log/owncloud.php
index 049b8dbdfa..0125164394 100644
--- a/lib/private/log/owncloud.php
+++ b/lib/private/log/owncloud.php
@@ -69,40 +69,40 @@ class OC_Log_Owncloud {
 	 * @param int $level
 	 */
 	public static function write($app, $message, $level) {
-		$minLevel=min(OC_Config::getValue( "loglevel", OC_Log::WARN ), OC_Log::ERROR);
-		if($level>=$minLevel) {
-			// default to ISO8601
-			$format = OC_Config::getValue('logdateformat', 'c');
-			$logtimezone=OC_Config::getValue( "logtimezone", 'UTC' );
-			try {
-				$timezone = new DateTimeZone($logtimezone);
-			} catch (Exception $e) {
-				$timezone = new DateTimeZone('UTC');
-			}
-			$time = new DateTime(null, $timezone);
-			$request = \OC::$server->getRequest();
-			$reqId = $request->getId();
-			$remoteAddr = $request->getRemoteAddress();
-			// remove username/passwords from URLs before writing the to the log file
-			$time = $time->format($format);
-			if($minLevel == OC_Log::DEBUG) {
-				$url = isset($_SERVER['REQUEST_URI']) ? $_SERVER['REQUEST_URI'] : '--';
-				$method = isset($_SERVER['REQUEST_METHOD']) ? $_SERVER['REQUEST_METHOD'] : '--';
-				$entry = compact('reqId', 'remoteAddr', 'app', 'message', 'level', 'time', 'method', 'url');
-			}
-			else {
-				$entry = compact('reqId', 'remoteAddr', 'app', 'message', 'level', 'time');
-			}
-			$entry = json_encode($entry);
-			$handle = @fopen(self::$logFile, 'a');
-			@chmod(self::$logFile, 0640);
-			if ($handle) {
-				fwrite($handle, $entry."\n");
-				fclose($handle);
-			} else {
-				// Fall back to error_log
-				error_log($entry);
-			}
+		$config = \OC::$server->getSystemConfig();
+
+		// default to ISO8601
+		$format = $config->getValue('logdateformat', 'c');
+		$logtimezone = $config->getValue( "logtimezone", 'UTC' );
+		try {
+			$timezone = new DateTimeZone($logtimezone);
+		} catch (Exception $e) {
+			$timezone = new DateTimeZone('UTC');
+		}
+		$time = new DateTime(null, $timezone);
+		$request = \OC::$server->getRequest();
+		$reqId = $request->getId();
+		$remoteAddr = $request->getRemoteAddress();
+		// remove username/passwords from URLs before writing the to the log file
+		$time = $time->format($format);
+		$minLevel=min($config->getValue( "loglevel", OC_Log::WARN ), OC_Log::ERROR);
+		if($minLevel == OC_Log::DEBUG) {
+			$url = isset($_SERVER['REQUEST_URI']) ? $_SERVER['REQUEST_URI'] : '--';
+			$method = isset($_SERVER['REQUEST_METHOD']) ? $_SERVER['REQUEST_METHOD'] : '--';
+			$entry = compact('reqId', 'remoteAddr', 'app', 'message', 'level', 'time', 'method', 'url');
+		}
+		else {
+			$entry = compact('reqId', 'remoteAddr', 'app', 'message', 'level', 'time');
+		}
+		$entry = json_encode($entry);
+		$handle = @fopen(self::$logFile, 'a');
+		@chmod(self::$logFile, 0640);
+		if ($handle) {
+			fwrite($handle, $entry."\n");
+			fclose($handle);
+		} else {
+			// Fall back to error_log
+			error_log($entry);
 		}
 	}
 
diff --git a/lib/private/log/syslog.php b/lib/private/log/syslog.php
index 1763e6de6d..8595b707d5 100644
--- a/lib/private/log/syslog.php
+++ b/lib/private/log/syslog.php
@@ -47,10 +47,7 @@ class OC_Log_Syslog {
 	 * @param int $level
 	 */
 	public static function write($app, $message, $level) {
-		$minLevel = min(OC_Config::getValue("loglevel", OC_Log::WARN), OC_Log::ERROR);
-		if ($level >= $minLevel) {
-			$syslog_level = self::$levels[$level];
-			syslog($syslog_level, '{'.$app.'} '.$message);
-		}
+		$syslog_level = self::$levels[$level];
+		syslog($syslog_level, '{'.$app.'} '.$message);
 	}
 }
diff --git a/tests/lib/logger.php b/tests/lib/logger.php
index 700a847917..9a9f5be12f 100644
--- a/tests/lib/logger.php
+++ b/tests/lib/logger.php
@@ -21,14 +21,38 @@ class Logger extends TestCase {
 		parent::setUp();
 
 		self::$logs = array();
-		$this->logger = new Log('Test\Logger');
+		$this->config = $this->getMockBuilder(
+			'\OC\SystemConfig')
+			->disableOriginalConstructor()
+			->getMock();
+		$this->logger = new Log('Test\Logger', $this->config);
 	}
 
 	public function testInterpolation() {
 		$logger = $this->logger;
-		$logger->info('{Message {nothing} {user} {foo.bar} a}', array('user' => 'Bob', 'foo.bar' => 'Bar'));
+		$logger->warning('{Message {nothing} {user} {foo.bar} a}', array('user' => 'Bob', 'foo.bar' => 'Bar'));
 
-		$expected = array('1 {Message {nothing} Bob Bar a}');
+		$expected = array('2 {Message {nothing} Bob Bar a}');
+		$this->assertEquals($expected, $this->getLogs());
+	}
+
+	public function testAppCondition() {
+		$this->config->expects($this->any())
+			->method('getValue')
+			->will(($this->returnValueMap([
+				['loglevel', \OC_Log::WARN, \OC_Log::WARN],
+				['log.condition', [], ['apps' => ['files']]]
+			])));
+		$logger = $this->logger;
+
+		$logger->info('Don\'t display info messages');
+		$logger->info('Show info messages of files app', ['app' => 'files']);
+		$logger->warning('Show warning messages of other apps');
+
+		$expected = [
+			'1 Show info messages of files app',
+			'2 Show warning messages of other apps',
+		];
 		$this->assertEquals($expected, $this->getLogs());
 	}