[AIRFLOW-566] Add timeout while fetching logs

Closes apache#1834 from msumit/AIRFLOW-566

airflow/configuration.py

@@ -251,6 +251,10 @@ def run_command(command):
 # privacy.
 demo_mode = False
 
+# The amount of time (in secs) webserver will wait for initial handshake
+# while fetching logs from other worker machine
+log_fetch_timeout_sec = 5
+
 [email]
 email_backend = airflow.utils.email.send_email_smtp
 
@@ -427,6 +431,7 @@ def run_command(command):
 web_server_host = 0.0.0.0
 web_server_port = 8080
 dag_orientation = LR
+log_fetch_timeout_sec = 5
 
 [email]
 email_backend = airflow.utils.email.send_email_smtp

airflow/www/views.py

@@ -75,6 +75,7 @@
 from airflow.utils import logging as log_utils
 from airflow.www import utils as wwwutils
 from airflow.www.forms import DateTimeForm, DateTimeWithNumRunsForm
+from airflow.configuration import AirflowConfigException
 
 QUERY_LIMIT = 100000
 CHART_LIMIT = 200000
@@ -759,7 +760,13 @@ def log(self):
                 log += "*** Fetching here: {url}\n".format(**locals())
                 try:
                     import requests
-                    response = requests.get(url)
+                    timeout = None  # No timeout
+                    try:
+                        timeout = conf.getint('webserver', 'log_fetch_timeout_sec')
+                    except (AirflowConfigException, ValueError):
+                        pass
+
+                    response = requests.get(url, timeout=timeout)
                     response.raise_for_status()
                     log += '\n' + response.text
                     log_loaded = True