Support Support Downloads Knowledge Base Case Manager My Juniper Community

Knowledge Base

Search our Knowledge Base sites to find answers to your questions.

Ask All Knowledge Base Sites All Knowledge Base Sites JunosE Defect (KA)Knowledge BaseSecurity AdvisoriesTechnical BulletinsTechnotes Sign in to display secure content and recently viewed articles

[WebApp Secure/Mykonos] Applications display as “Down” in the JWAS WebUI system status but are reachable



Article ID: KB30317 KB Last Updated: 12 Mar 2015Version: 1.0

The Junos WebApp Secure (JWAS) health check mechanism reaches out to back-end applications to check the status at regular intervals. Back-end applications show the System Status > Backend Health as down, even though the applications are reachable.


JWAS gets the health check report of a back-end application by running the curl command in the background for an HTTP request of the host header of the application. If this command doesn’t fetch the HTTP 200 OK result, then the back-end application is marked as down.

The following is an example of a working health check:

[mykonos@JWAS1-88 ~]$ curl -I --header 'Host:'
HTTP/1.1 200 OK
Server: nginx/1.1.19
Date: Fri, 06 Mar 2015 17:42:03 GMT
Content-Type: text/html; charset=utf-8
Connection: keep-alive
X-Powered-By: PHP/5.3.10-1ubuntu3.9
Set-Cookie: 645ec67d384adf7bccfae1d21da65e23=ej34qjgd3nd1evjpuh20nboem1; path=/; HttpOnly
Expires: Mon, 1 Jan 2001 00:00:00 GMT
Last-Modified: Fri, 06 Mar 2015 17:42:03 GMT
Cache-Control: no-store, no-cache, must-revalidate, post-check=0, pre-check=0
Pragma: no-cache

By default, the global back-end health check settings are applicable for all applications, and the setting is HEAD / HTTP/1.0 under Configuration > Proxy/Backend. However, when multiple applications are configured, the health check URL must be defined as specifically as possible in order for the HTTP request for the host header to go through.


To configure application-level health check settings, go to Configuration > Applications > application_name > Health Check and modify the setting.

To monitor the HTTP host header:
Append \r\nHost: <host-header> for the application; for example, the health check URL will be HEAD / HTTP/1.0\r\nHost: <host-header>.

To monitor the Web page:
If there is a requirement to monitor the Web page instead of the HTTP host header, change the URL from HEAD / HTTP/1.0 to HEAD <webpage_url> HTTP/1.0.
For example, if the Web page to be monitored is /app/app.status, then it would be changed from HEAD / HTTP/1.0 to HEAD /app/app.status HTTP/1.0.

To monitor both the Web page and host header:
If the host header is also needed, then it would be HEAD <webpage_url> HTTP/1.0\r\nHost: <host-header>.
For example, if the Web page to be monitored is, along with the host header, then it would be HEAD /app/app.status HTTP/1.0\r\nHost:

Verify if the health check passes by running the following command:

curl -I --header 'Host: <host_header_of_application>' <application_ip>

If the request results in an HTTP 200 OK result as shown in the example above, then the application will appear as UP in the system status of the WebUI.

Comment on this article > Affected Products Browse the Knowledge Base for more articles related to these product categories. Select a category to begin.

Getting Up and Running with Junos

Getting Up and Running with Junos Security Alerts and Vulnerabilities Product Alerts and Software Release Notices Problem Report (PR) Search Tool EOL Notices and Bulletins JTAC User Guide Customer Care User Guide Pathfinder SRX High Availability Configurator SRX VPN Configurator Training Courses and Videos End User Licence Agreement Global Search