/*
* Weblounge: Web Content Management System
* Copyright (c) 2011 The Weblounge Team
* http://weblounge.o2it.ch
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public License
* as published by the Free Software Foundation; either version 2
* of the License, or (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public License
* along with this program; if not, write to the Free Software Foundation
* Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
*/
package ch.entwine.weblounge.kernel.http;
import ch.entwine.weblounge.common.site.Site;
import ch.entwine.weblounge.kernel.site.SiteManager;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import java.io.IOException;
import java.util.Iterator;
import javax.servlet.Filter;
import javax.servlet.FilterChain;
import javax.servlet.FilterConfig;
import javax.servlet.ServletException;
import javax.servlet.ServletRequest;
import javax.servlet.ServletResponse;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
/**
* Filter that will answer health checks typically sent by load balancers or
* service monitors.
*/
public class HealthCheckFilter implements Filter {
/** The logger */
protected static final Logger logger = LoggerFactory.getLogger(HealthCheckFilter.class);
/** URI for the health of this instance */
private static final String HEALTHCHECK_URI = "/weblounge-health";
/** The sites that are online */
protected SiteManager sites = null;
/**
* Creates a new weblounge health request filter.
*/
public HealthCheckFilter() {
}
/**
* {@inheritDoc}
*
* @see javax.servlet.Filter#init(javax.servlet.FilterConfig)
*/
public void init(FilterConfig filterConfig) throws ServletException {
// Is not being called
}
/**
* {@inheritDoc}
*
* @see javax.servlet.Filter#doFilter(javax.servlet.ServletRequest,
* javax.servlet.ServletResponse, javax.servlet.FilterChain)
*/
public void doFilter(ServletRequest request, ServletResponse response,
FilterChain chain) throws IOException, ServletException {
// Make sure the site manager has been set
if (sites == null) {
logger.trace("All sites are currently offline");
((HttpServletResponse) response).setStatus(HttpServletResponse.SC_CONFLICT);
return;
}
// Extract site from the request
if (request instanceof HttpServletRequest) {
HttpServletRequest httpRequest = (HttpServletRequest) request;
if (HEALTHCHECK_URI.equals(httpRequest.getRequestURI())) {
Iterator<Site> si = sites.sites();
while (si.hasNext()) {
Site site = si.next();
if (!site.isOnline()) {
logger.trace("Site {} is marked as offline", site.getIdentifier());
logger.trace("Reporting bad health to {}", httpRequest.getRemoteHost());
((HttpServletResponse) response).setStatus(HttpServletResponse.SC_CONFLICT);
return;
}
}
logger.trace("Reporting good health to {}", httpRequest.getRemoteHost());
((HttpServletResponse) response).setStatus(HttpServletResponse.SC_OK);
return;
}
}
// No health check, resume as usual
chain.doFilter(request, response);
}
/**
* {@inheritDoc}
*
* @see javax.servlet.Filter#destroy()
*/
public void destroy() {
// Nothing to do
}
/**
* Callback for OSGi to set the site manager.
*
* @param siteManager
* the site manager
*/
void setSiteManager(SiteManager siteManager) {
this.sites = siteManager;
}
/**
* {@inheritDoc}
*
* @see java.lang.Object#toString()
*/
@Override
public String toString() {
return "Healtch check filter";
}
}