CentOS check system info

Show system inf for a CentOS server:

# CPU info
 more /proc/cpuinfo

# Memory info
 dmidecode -t memory
 dmidecode -t memory | grep -i "installed size"

# Operatin System
 cat /etc/os-release
 hostnamectl
 uname -r

SoapUI escape dollar variable "${}"

If you need to escape "${some-text}" you have to put "$${some-text}"

Axis 1 - SLF4J Logging

In this post I´ll show you how to configure Axis 1 Logging with SLF4J-Log4j. The main purpose is to trace incoming and outcoming messages.

Axis uses Apache commons-logging as logging implementation. This dependecy is configured as runtime in Axis pom, so it will not be imported as transitive.
Any way, if you have commons-logging library in your project, exclude it.

As you exclude commons-logging, you need to add the corresponding slf4j bridge, i.e., jcl-over-slf4j library.

Add a file called common-logging.properties in src/main/resoruces with the following content:

org.apache.commons.logging.LogFactory=org.apache.commons.logging.impl.SLF4JLogFactory

When you configure log4j logging, for example in log4j.xml file,  add the following categories:

<logger name="org.apache.axis.providers" additivity="false">
 <level value="debug"/>
 <appender-ref ref="FILE"/>
</logger>

<logger name="org.apache.axis.transport.http" additivity="false">
 <level value="debug"/>
 <appender-ref ref="FILE"/>
</logger>

org.apache.axis.providers is used by web service providers in order to trace incoming messages and outcoming responses.

org.apache.axis.transport.http is used by web service clientes in order to trace outcoming messages and incoming responses.

CentOS 6 - Port forwarding

I have the following scenario:

1. My computer
2. CentOS 6.5 intermediate server IP_CENTOS
3. Third party service: https://IP_SERVICE/domain/service-path 

From my computer I can reach the CentOS server, but not the third party service.

From CentOS server you can reach the third party service.

I want to use CentOS server as a bridge in order to forward traffic from my computer to the third party service and vice versa.

Set configuration

Step 1

Enable ip forward in iptables:

 
    echo 1 >/proc/sys/net/ipv4/ip_forward

Step 2

Configure forwarding:

    iptables -t nat -A PREROUTING -p tcp --dport 9443 -j DNAT --to-destination [IP_SERVICE]:443
    iptables -t nat -A POSTROUTING -p tcp -d [IP_SERVICE] --dport 443 -j SNAT --to-source [IP_CENTOS]

Here you have:

• 9443 is the fake port used in CentOS server.
• IP_SERVICE is the IP address of the third party service
• 443 is the default HTTPS port, as the third party service is in https://xxxxxx
• IP_CENTOS is the IP address of the CentOS server

Step 3

Save the rules:

    service iptables save
    service iptables reload

You can check the configuration as follow:

    iptables -t nat --line-numbers -L

    more /etc/sysconfig/iptables

Test

From My Computer you can check to access to https://IP_CENTOS:9443/domain/service-path 

Rollback configuration

In order to restore configuration and delete all previous work, do as follows:

    echo 0 >/proc/sys/net/ipv4/ip_forward

Check the rules and delete them one by one:

    iptables -t nat --line-numbers -L

    iptables -t nat -D PREROUTING|POSTROUTING [num]

Apache Camel - Proxy route

In this example I will configure a Camel route proxy. Camel will publish a http servlet and redirect all request to a external provider.

Configuration

You need to configure as follow:

• Configure dependencies
• Configure Camel servlet
• Configure Camel route

Configure dependencies

In pom.xml:

<dependency>
 <groupId>org.apache.camel</groupId>
 <artifactId>camel-servlet</artifactId>
 <version>${camel.version}</version> 
</dependency>

<dependency>
 <groupId>org.apache.camel</groupId>
 <artifactId>camel-http4</artifactId>
 <version>${camel.version}</version> 
</dependency>

Configure Camel servlet

In web.xml:

<servlet>
 <servlet-name>CamelServlet</servlet-name>
 <display-name>Camel Http Transport Servlet</display-name>
 <servlet-class>org.apache.camel.component.servlet.CamelHttpTransportServlet</servlet-class>
</servlet>

<servlet-mapping>
 <servlet-name>CamelServlet</servlet-name>
 <url-pattern>/services/*</url-pattern>
</servlet-mapping>

Or, alternatively, in java:

import javax.servlet.annotation.WebServlet;

@WebServlet(name = "CamelServlet", urlPatterns = { "/services/*" }, loadOnStartup = 1)
public class CamelRestServlet extends org.apache.camel.component.servlet.CamelHttpTransportServlet { 
 private static final long serialVersionUID = 2886685336873526067L;
 //Servlet secuestrado por Camel para procesar las peticiones de entrada a su ruta proxy
}

Configure Camel route

In camel-context.xml:

<camelContext id="camelContext" xmlns="http://camel.apache.org/schema/spring">
 <route>
  <from uri="servlet:/service1?matchOnUriPrefix=true"/>
  <log message="Redirecting to service1"/>
  <to uri="http4://otherDomain:8080/otherApp/service1?bridgeEndpoint=true&amp;throwExceptionOnFailure=false"/>
 </route>
 
 
 <route>
  <from uri="servlet:/service2?matchOnUriPrefix=true"/>
  <log message="Redirecting to service2"/>
  <to uri="http4://otherDomain:8080/otherApp/service2?bridgeEndpoint=true&amp;throwExceptionOnFailure=false"/>
 </route>
</camelContext>

Testing

In your app is published in http://localhost:8080/myApp, then you will get the following behaviour:

When calling http://localhost:8080/myApp/services/service1/test?a=b Camel will redirect to http://otherDomain:8080/otherApp/service1/test?a=b