diff --git a/README.md b/README.md
index 7e31a47..ca616ae 100644
--- a/README.md
+++ b/README.md
@@ -60,6 +60,7 @@ Supported environment parameters:
 - PROCESSORS_PATH - path where result processors can be found. If not specified, "processors" directory is used
 - PROCESSORS_PARALLELISM - number of data processors that can be executed in parallel. If not present, number of CPU cores is used.
 - METRICS_BATCH_SIZE - batch size to use when sending data to metrics gateway
+- LOG_LEVEL configures log level. TRACE, DEBUG, INFO, WARN, ERROR, FATAL are valid values.
 
 ## Building
 
@@ -96,5 +97,4 @@ Unless at least one processor is available the process will exit immediately. No
   - related to the fact we don't store processor execution state/result
 - currently there is no way for processor to tell the service version of the produced content. All result processors must thus produce data of the same version. Metrics gateway service may support multiple data format versions (i.e v1, v2 on its REST). If case of change we have to update code of all result processors.
   - if needed this could be solved by processor descriptor saying what data it produces on STDOUT and for whom
-- log level is not passed to data processor, it may result in unnecessary messages being sent to STDERR then being filtered out
 - no support for chaining multiple processors after each other. Celery supports this. We could use more streams than STDOUT and processor descriptor could specify where the stream output should go (i.e metrics-gateway or other processor).
diff --git a/server.js b/server.js
index e21e613..2dcec80 100644
--- a/server.js
+++ b/server.js
@@ -10,6 +10,9 @@
 var log4js = require('log4js');
 // replaces console.log function with log4j
 log4js.replaceConsole();
+if (process.env.LOG_LEVEL) {
+    log4js.setGlobalLogLevel(process.env.LOG_LEVEL);
+}
 var logger = log4js.getLogger('server.js');
 
 var grace = require('grace');
diff --git a/service/manager.js b/service/manager.js
index f35efd3..194efa5 100644
--- a/service/manager.js
+++ b/service/manager.js
@@ -47,7 +47,12 @@ function getProcessorNames(processorDescs) {
  */
 function msgConsumer(msg, ackControl) {
     var contentStr = msg.content.toString();
-    logger.debug(" [x] Received '%s'", contentStr);
+    if (logger.isLevelEnabled(log4js.levels.TRACE)) {
+        logger.trace(" [x] Received '%s'", contentStr);
+    } else if (logger.isLevelEnabled(log4js.levels.DEBUG)) {
+        // with debug level log less
+        logger.debug(" [x] Received '%s...'", contentStr.substr(0, 50));
+    }
     // process file
     var processingMetadata = msg.properties.headers; // path, accessToken, tenantId
     var contentMetadata = JSON.parse(contentStr);
diff --git a/service/metrics-gateway.js b/service/metrics-gateway.js
index a7f1ea7..8a4b3be 100644
--- a/service/metrics-gateway.js
+++ b/service/metrics-gateway.js
@@ -31,8 +31,10 @@ function getSendUri() {
  * @param callback callback that will be notified upon success/error
  */
 function send(processingMetadata, data, callback) {
-    if (logger.level.level <= log4js.levels.DEBUG.level) {
+    if (logger.isLevelEnabled(log4js.levels.TRACE)) {
         logger.debug('Sending to /mgs/rest/v1/gateway/event: ' + JSON.stringify(data));
+    } else if (logger.isLevelEnabled(log4js.levels.DEBUG)) {
+        logger.debug('Sending to /mgs/rest/v1/gateway/event: ' + JSON.stringify(data).substr(0, 50) + '...');
     }
 
     var body = JSON.stringify(Array.isArray(data) ? data : [data]);
diff --git a/service/processors.js b/service/processors.js
index 8142ec5..5c43089 100644
--- a/service/processors.js
+++ b/service/processors.js
@@ -30,9 +30,15 @@ var processorsMap = {};
 var childLogRegExp = new RegExp('([A-Z]+):([^:]+):(.*)');
 
 /**
- * Map of supported data processor log levels. Corresponds to Python logger log levels.
+ * Map of Python log levels used by child processor logger to log4js log levels.
  */
-var childLogLevelMap = {'DEBUG': 'debug', 'INFO': 'info', 'WARNING': 'warn', 'ERROR': 'error', 'CRITICAL': 'fatal'};
+var childLogLevelMap = {'DEBUG': 'DEBUG', 'INFO': 'INFO', 'WARNING': 'WARN', 'ERROR': 'ERROR', 'CRITICAL': 'FATAL'};
+
+/**
+ * Map of log4js level strings to Python log levels used by child processor logger.
+ */
+var log4jsToChildLogLevelMap = {'ALL': 'DEBUG', 'TRACE': 'DEBUG', 'DEBUG': 'DEBUG', 'INFO': 'INFO', 'WARN': 'WARNING',
+    'ERROR': 'ERROR', 'FATAL': 'CRITICAL', 'MARK': 'CRITICAL', 'OFF': 'CRITICAL'};
 
 /**
  * Verifies processor at given path with given descriptor. Performs verification of the descriptor and test execution of
@@ -185,9 +191,10 @@ function onLogFromChild(processorDesc, str) {
  * has to use specialized argument parsing libraries which may be buggy or work differently. Its much easier to access
  * process environment variables. Environment variables will be prefixed with P_. String case is preserved.
  *
+ * @param processorDesc
  * @param contentMetadata
  */
-function getEnvParams(contentMetadata) {
+function getEnvParams(processorDesc, contentMetadata) {
     var envParams = util._extend({}, process.env);
     var keys = Object.keys(contentMetadata);
     for (var i = 0; i < keys.length; i++) {
@@ -195,6 +202,9 @@ function getEnvParams(contentMetadata) {
         // we convert key to uppercase since in Windows env variable keys are not case sensitive, while in Linux they are
         envParams['P_' + key.toUpperCase()] = contentMetadata[key];
     }
+    // translate log level
+    var log4jsLevel = processorDesc.logger.level.levelStr;
+    envParams['P_LOG_LEVEL'] = log4jsToChildLogLevelMap[log4jsLevel];
     return envParams;
 }
 
@@ -232,7 +242,7 @@ function exec(command, options) {
 function executeProcessor(processorDesc, processingMetadata, contentMetadata) {
     logger.debug('Executing processor ' + processorDesc.name);
     var readStream = fs.createReadStream(processingMetadata.path);
-    var envParams = getEnvParams(contentMetadata);
+    var envParams = getEnvParams(processorDesc, contentMetadata);
     var child = exec(processorDesc.command, {cwd: processorDesc.path, env: envParams});
     child.once('error', function(err) {
         logger.debug('Execution of processor failed ', err);
diff --git a/tests/system/dev-processors/dummy/processor.js b/tests/system/dev-processors/dummy/processor.js
index 219ac8f..2137212 100644
--- a/tests/system/dev-processors/dummy/processor.js
+++ b/tests/system/dev-processors/dummy/processor.js
@@ -1,23 +1,27 @@
 'use strict';
 
-console.error('Some sample logging');
+var logLevelsMap = {
+    'DEBUG': 1, 'INFO': 2, 'WARNING': 3, 'ERROR': 4, 'CRITICAL': 5
+};
+
+log('DEBUG', 'processor.js', 'Some sample logging');
 
 var paramCount = 0;
-console.error('Process parameters:');
+log('DEBUG', 'processor.js', 'Process parameters:');
 var keys = Object.keys(process.env);
 for (var i = 0; i < keys.length; i++) {
     var key = keys[i];
     if (key.lastIndexOf('P_', 0) === 0) {
         var value = process.env[key];
         paramCount++;
-        console.error(key.substr(2) + ' = ' + value);
+        log('DEBUG', 'processor.js', key.substr(2) + ' = ' + value);
     }
 }
 
-console.error('Process stdin:');
+log('DEBUG', 'processor.js', 'Process stdin:');
 process.stdin.setEncoding('utf8');
 process.stdin.on('data', function(str) {
-    console.error(str);
+    log('DEBUG', 'processor.js', str);
 });
 process.stdin.on('end', function() {
     process.exit(0);
@@ -46,3 +50,11 @@ for (var i = 0; i < 50; i++) {
     }));
 }
 console.log(']');
+
+function log(level, location, message) {
+    var logLevel = logLevelsMap[level];
+    var configuredLogLevel = logLevelsMap[process.env.P_LOG_LEVEL || 'DEBUG'];
+    if (logLevel >=  configuredLogLevel) {
+        console.error(level + ':' + location + ':' + message);
+    }
+}