Lab 2.3 - Setup the Agents
==========================

Once the master is setup and running, we need to setup and join our **agents**
to the cluster.

.. important:: The following commands need to be run on both **agent** nodes
   unless otherwise specified.

Install Mesos
-------------

#. Add the mesos/marathon repo

   Run the following commands:

   .. code-block:: bash

      apt-key adv --keyserver keyserver.ubuntu.com --recv E56151BF

      cat <<EOF >> /etc/apt/sources.list.d/mesosphere.list
      deb http://repos.mesosphere.com/ubuntu $(lsb_release -cs) main
      EOF

#. Install the mesos packages

   .. code-block:: bash

      apt update && apt-get install mesos -y

Setup Mesos
-----------

#. Create mesos `ip` file /etc/mesos-slave/ip
#. Create mesos `hostname` file /etc/mesos-slave/hostname (specify the IP
   address of your node)
#. Point zookeeper to the master instance. This is done in the file
   /etc/mesos/zk

   .. code-block:: bash

      # On agent1
      echo "10.2.10.22" > /etc/mesos-slave/ip
      echo "10.2.10.22" > /etc/mesos-slave/hostname
      echo "zk://10.2.10.21:2181/mesos" > /etc/mesos/zk

      # On agent2
      echo "10.2.10.23" > /etc/mesos-slave/ip
      echo "10.2.10.23" > /etc/mesos-slave/hostname
      echo "zk://10.2.10.21:2181/mesos" > /etc/mesos/zk

#. Make the following changes to allow "docker" containers with mesos.

   .. code-block:: bash

      #Add the ability to use docker containers
      echo 'docker,mesos' > /etc/mesos-slave/containerizers

      #Increase the timeout to 5 min so that we have enough time to download any needed docker image
      echo '5mins' > /etc/mesos-slave/executor_registration_timeout

      #Allow users other then "marathon" to create and run jobs on the agents
      echo 'false' > /etc/mesos-slave/switch_user

Start Services
--------------

#. First we need to make sure that zookeeper and mesos-master don't run on the
   agents.

   .. code-block:: bash

      systemctl stop zookeeper
      echo manual > /etc/init/zookeeper.override

      systemctl stop mesos-master
      echo manual > /etc/init/mesos.master.override

#. Start & enable the agent process called mesos-slave

   .. code-block:: bash

      systemctl start mesos-slave
      systemctl enable mesos-slave

#. Check on master with mesos interface (port 5050) if your agents registered
   successfully. You should see both agent1 and agent2 on the agent page.

   .. image:: images/setup-slave-check-agent-registration.png

Test Your Setup
---------------

Connect to Marathon through one of the master (8080) and launch an application.

#. Click on *create application*

   .. image:: images/setup-slave-test-create-application-button.png

#. Make the following settings and click "Create Application"

   - ID: test
   - CPU: 0.1
   - Memory: 32M
   - Command: echo TEST; sleep 5

   .. image:: images/setup-slave-test-create-application-command-def.png

#. Once it starts, connect to the mesos framework.  Here you should see more
   and more completed tasks. Name of the task should be "test" (our ID).

   .. image:: images/setup-slave-test-create-application-command-exec1.png

#. If you let it run for a while, you'll see more and more "Completed Tasks".
   You can see that the Host being selected to run those tasks is not always
   the same.

   .. image:: images/setup-slave-test-create-application-command-exec2.png

#. Go Back to Marathon, click on our application *test* and click on the
   setting button and select *destroy* to remove it.

   .. image:: images/setup-slave-test-create-application-command-delete.png

Launch A Container
------------------

To test our containers from marathon. We will start a simple apache container.

#. Click on create an application, switch to JSON mode and replace
   the default 8 lines of json with the following and Click "Create
   Application"

   .. note:: This may takes some time since we will have to retrieve the
      image first

   .. code-block:: json

      {
         "id": "my-website",
         "cpus": 0.5,
         "mem": 32.0,
         "container": {
            "type": "DOCKER",
            "docker": {
               "image": "eboraas/apache-php",
               "network": "BRIDGE",
               "portMappings": [
                  { "containerPort": 80, "hostPort": 0 }
               ]
            }
         }
      }

   .. image:: images/setup-slave-test-create-container-def.png

#. It may take some time to switch from ``Deploying`` to ``Running``.

   .. image:: images/setup-slave-test-create-container-run.png

#. Once it's in a ``Running`` state, find the port used by the container and
   try to access it at agent IP:port. Click on your application "my-website".
   Here you'll see the port associated to your instance. In this case it's
   ``31870`` and on ``agent1 - 10.2.10.22``

   .. image:: images/setup-slave-test-create-container-check-port.png

#. Use your browser to connect to the application:

   .. image:: images/setup-slave-test-create-container-access.png