Merge pull request #167 from alphagov/logstash_json

Add json log formatter

.gitignore

@@ -10,7 +10,7 @@ assets/*
 .coverage
 build
 coverage.xml
-*.log
+*.log*
 nosetests.xml
 pep8.out
 tmp/*

backdrop/core/log_handler.py

@@ -1,4 +1,5 @@
 from logging import FileHandler
+from logstash_formatter import LogstashFormatter
 import logging
 from flask import request
 
@@ -11,11 +12,21 @@ def get_log_file_handler(path, log_level=logging.DEBUG):
     return handler
 
 
+def get_json_log_handler(path):
+    handler = FileHandler(path)
+    formatter = LogstashFormatter()
+    handler.setFormatter(formatter)
+    return handler
+
+
 def set_up_logging(app, name, env):
     log_level = logging._levelNames[app.config['LOG_LEVEL']]
     app.logger.addHandler(
         get_log_file_handler("log/%s.log" % env, log_level)
     )
+    app.logger.addHandler(
+        get_json_log_handler("log/%s.log.json" % env)
+    )
     app.logger.setLevel(log_level)
     app.logger.info("Backdrop %s API logging started" % name)
 

requirements.txt

@@ -2,11 +2,12 @@ argh==0.23.3
 Flask==0.10.1
 Flask-FeatureFlags==0.3
 gunicorn==18.0
+invoke
+logstash-formatter==0.5.5
 pip==1.4.1
 pymongo==2.6.1
 python-dateutil==2.1
 pytz==2013b
-statsd==2.0.3
 rauth==0.5.4
+statsd==2.0.3
 xlrd==0.9.2
-invoke

tests/core/test_json_logging.py

@@ -0,0 +1,30 @@
+from hamcrest import assert_that, has_entries
+import os
+import logging
+import json
+from backdrop.core import log_handler
+import unittest
+from flask import Flask
+
+
+class TestJsonLogging(unittest.TestCase):
+
+    def setUp(self):
+        self.app = Flask('json_test_app')
+        self.logger = self.app.logger
+        self.app.config['LOG_LEVEL'] = logging.DEBUG
+
+    def test_json_log_written_when_logger_called(self):
+
+        log_handler.set_up_logging(self.app, 'json_test', 'json_test')
+        self.logger.info('Writing out JSON formatted logs m8')
+
+        with open('log/json_test.log.json') as log_file:
+            data = json.loads(log_file.readlines()[-1])
+
+        assert_that(data, has_entries({
+            '@message': 'Writing out JSON formatted logs m8'
+        }))
+
+        # Only remove file if assertion passes
+        os.remove('log/json_test.log.json')