Installing an Agent

A Roboconf agent is an OSGi application which is in charge of executing instructions on the host it is deployed on.
These instructions are either given by the DM, or deduced by the agent from a change in the global application. As an example, if there is a web application on the host, and that it depends on a database, and that the database is undeployed, then the agent will stop the web application.

The instructions, as well as the notifications, all go through the messaging server.

A Roboconf agent is associated to a given application.
And more specifically, it is tied to a single root instance in this application. A root instance designates a machine in Roboconf’s DSL. So, an agent will undertake and communicate about all the applications parts that are deployed on the same host than it.

To install a Roboconf agent, you must have:

Although we generally test Roboconf with Ubuntu systems, there is no reason it does not work on other systems.
However, we recommend using Linux systems.

Several options are available to install an agent.

This page only describes how to install an agent.
Take a look at this page to see how to configure it.

Root Access

The agent will install and modify applications on the host.
To run correctly, the agent must run with root privileges.

Besides, an agent should be configured to start with the machine / VM.
This is necessary if you deploy in a cloud environment.

On Linux systems, making a program start with the operating system can be achieved a init.d script.
You can also edit the /etc/rc.local file and launch the program at the end of the script.

If you use Karaf, there are commands to automatically register the server as a service.
And if you install the Debian package, all of this is handled automatically for you.

Installing Java

Installing Java is described in several places all over the web.
Here are some short links and snippets to make you gain some time. Take a look at this page as an example.

sudo apt-get update
sudo apt-get install openjdk-7-jdk

And define the JAVA_HOME environment variable.
On Ubuntu 14.04, the following command installs Java here…

/usr/lib/jvm/java-7-openjdk-amd64/jre

If you use Karaf, you can define this variable in the Karaf’s bin/setenv file.

The Custom Karaf Distribution for the Agent

Apache Karaf is an OSGi server.
It brings additional features to OSGi containers like Felix (Apache) or Equinox (Eclipse). It also allows to build custom distributions with pre-installed bundles and their configurations. The custom Karaf distribution for the agent is thus a stand-alone server with the Roboconf’s agent being already deployed and configured. It is configured to run with Apache Felix.

Having several Karaf servers on a machine can result in port conflicts. If it is your case, you may have to configure the ports differently. Or you may prefer deploying our Karaf feature.

This distribution can be deployed either with a Debian package or manually.
To deploy it manually, you must have a JDK 7 installed. Then, download the agent’s ZIP archive and unzip it somewhere on your disk.

To start it, execute…

cd bin
sudo ./karaf

This opens an interactive shell.
To exit, type in…

logout

You can find help and more instructions about Karaf on its web site.
Anyway, you need to make Karaf start at boot time with the system. Fortunately, Karaf has very useful features such as system wrappers.

# Start the agent
cd bin
sudo ./karaf

# Install the service wrapper
feature:install service-wrapper

# Create a service for the agent
wrapper:install -n roboconf-agent

# Exit Karaf
logout

# Install the service
sudo ln -s /home/ubuntu/roboconf-karaf-dist-agent-%v_SNAP%/bin/roboconf-agent-service /etc/init.d/

# Configure it to boot with the system
sudo update-rc.d roboconf-agent-service defaults

# Just to be sure, you can check the main script
more ../etc/roboconf-agent-wrapper.conf

Now, restart your system and make sure the agent runs.

Note: you can test directly the installation, by running “sudo /etc/init.d/roboconf-agent-service start”, and checking the “data/log/wrapper.log” file. If you get some trouble finding the JVM:

When everything looks fine, then, reboot:

# Clear the logs (you were in the "bin" directory).
cd ../data/log
rm -rf *

# Restart.
sudo reboot

# Reconnect to the VM through SSH (...).
# Check the logs.
cd roboconf-agent/data/log

# If the agent is running, there will be logs.

The Agent Feature for Karaf

If you already have your own Karaf server, you may prefer to install the agent as a feature.
The agent feature is a XML file that lists the bundles to install and some of their dependencies so that the agent works.

We do not have any official release yet.
However, you can add our snapshot repository to the list of features repository.

Start your karaf and execute…

# Add the feature URL
feature:repo-add http://repo1.maven.org/maven2/net/roboconf/roboconf-karaf-feature-agent/%v_SNAP%/roboconf-karaf-feature-agent-%v_SNAP%-features.xml

# Install the feature 
feature:install roboconf-agent

For the record, the roboconf-agent feature depends on the following features:

The Agent Bundles

It is possible to deploy the agent bundles directly in Felix, Equinox or any other OSGi container.
To determine all the required bundles, take a look at the Karaf feature described above. The previous section also lists their dependencies (as other Karaf features).