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Troubleshooting webserver issues

Report table

Issue How to find Time to find How to fix Time to fix
Connection timed out netstat -tulnap iptables -L -n 5m Open required ports on firewall 10m
Connection timeout after server reboot iptables -L -n Rules are not saved Trying "service iptables save" Error: cannot write to iptables file. Check syslinux permissions, check extended file attributes ls -la iptables ls -lZ iptables lsattr iptables Immutable attribute was set. 2h chattr -i iptables 5m
1 Redirected to http://mntlab while accessing webserver address. http://mntlab - server not found Check httpd/vhost configs for Redirect directive 5m Replace Redirect directive with ProxyPass ProxyPass "/" "http://mntlab" 5m
2 Warning "ServerName is not set..." during httpd reload Check httpd.conf for ServerName directive 5m Add ServerName directive ServerName 127.0.0.1 5m
3 Still no page in browser Check mod_jk logs and config files: /var/log/httpd/modjk.log vhost.conf workers.properties mod_jk is not configured correctly. 15m Correct worker definition worker.list=tomcatworker worker.template.type=ajp13worker.template.ping_mode=A worker.template.socket_connect_timeout=1000 worker.template.connection_pool_timeout=60 worker.template.socket_keepalive=True worker.tomcatworker.port=8009 worker.tomcatworker.host=192.168.56.10 15m
4 Still no page in browser Check tomcat is running service tomcat status sudo netstat -tulnap Status is running, no ports are listening. cat /etc/init.d/tomcat 15m Correct tomcat startup script Remove /dev/null redirection, remove "success" in order to get output from script 10m
5 Still no page in browser Tomcat is not running. Trying to start. Error: classpath file not found. Checking logs for any error. Logs folder is empty. Checking logs folder attributes. Checking environment variables required for tomcat. setenv.sh, tomcat user's .bashrc file. 20m Set log files folder ownership. Set correct environment variables in setenv.sh 15m
6 Java is broken java -version alternatives --config java 15m Configure java via alternatives 15m
7 503 error after server reboot service tomcat status tomcat is stopped. 5m chkconfig tomcat on 5m

Additional questions

  • What java version is installed?
[vagrant@mntlab ~]$ java -version
java version "1.7.0_79"
Java(TM) SE Runtime Environment (build 1.7.0_79-b15)
Java HotSpot(TM) 64-Bit Server VM (build 24.79-b02, mixed mode)
  • How was it installed and configured?

It was installed using archive binary file jdk-7u79-linux-(i586|x64).tar.gz, because there is no info about it in rpm database. Installation directory is /opt/oracle/java/(i586|x64)/jdk1.7.0_79. In order to use this java version it was configured using alternatives.

  • Where are log files of tomcat and httpd?

tomcat: /opt/apache/tomcat/current/logs/

httpd: /var/log/httpd/

  • Where is JAVA_HOME and what is it?

JAVA_HOME is an environment variable that points to the path where java is installed. In our case it is: /opt/oracle/java/x64/jdk1.7.0_79

  • Where is tomcat installed?

/opt/apache/tomcat/7.0.62/

  • What is CATALINA_HOME?

Environment variable that points to tomcat installation directory.

  • What users run httpd and tomcat processes? How is it configured?

Httpd parent process is run by root, because it is required to bind to privileged port (80). Child processes are run by user "apache". It is configured in httpd.conf.

Tomcat runs with privileges of user "tomcat". It is configured in tomcat init script.

  • What configuration files are used to make components work with each other?

httpd:

-- httpd.conf: include vhost.conf

-- vhost.conf: load and configure mod_jk module, define vhost

-- workers.properties: define workers

tomcat:

-- server.xml: define ajp connector

-- setenv.sh: define environment variables required by tomcat

  • What does it mean: “load average: 1.18, 0.95, 0.83”?

First, lets assume the given values are from single CPU machine.

Over the last minute the system was overloaded by 18%, on average 0.18 processes were waiting for CPU.

Over the last 5 minutes the CPU was idle for 5% of time.

Over the last 15 minutes the CPU was idle for 17% of time.

  • In what cases does cp prompt to overwrite file and in what not?

will prompt: -- cp -i