Merge pull request #75 from grnet/devel

Merge devel to master

.travis.yml

----
 language: python
-python: "2.7"
-
-before_install:
-  # Make sure everything's up to date.
-  - sudo apt-get update -qq
-
-install:
-  # Install Ansible.
-  - pip install ansible
-
-  # Add ansible.cfg to pick up roles path.
-  - "printf '[defaults]\nroles_path = ../../' > ansible.cfg"
+python: 
+ - "2.7"
 
+install: 
+ - pip install tox
+ - pip install flake8-diff
 script:
-  # We'll add some commands to test the role here.
-  #- cd ansible/roles/common/tests && ansible-playbook -i inventory test.yml  --syntax-check
-  #- ansible-playbook -i inventory test.yml  --connection=local --sudo 
-  #- "ansible-playbook -i inventory test.yml --connection=local --sudo | tee /tmp/output.txt; grep -q 'changed=0.*failed=0' /tmp/output.txt && (echo 'Idempotence test: pass' &&  exit 0) || (echo 'Idempotence test: fail' && exit 1)"
-  - cd ansible/roles/apache-flink/tests 
-  # Check the role/playbook's syntax.
-  - ansible-playbook -i inventory test.yml  --syntax-check
-  # Run the role/playbook with ansible-playbook.
-  - ansible-playbook -i inventory test.yml  --connection=local --sudo 
-  # Run the role/playbook again, checking to make sure it's idempotent.
-  - ansible-playbook -i inventory test.yml  --connection=local --sudo 
-    | grep -q 'changed=0.*failed=0'
-    && (echo 'Idempotence test: pass' && exit 0)
-    || (echo 'Idempotence test: fail' && exit 1)
-  # Some MySQL debugging (show all the logs).
-  - "sudo ls -lah /var/log"
-  - "sudo cat /var/log/apache-flink/error.log"
-  - "sudo wget -O hamlet.txt http://www.gutenberg.org/cache/epub/1787/pg1787.txt"
-  - "sudo bin/flink run ./examples/flink-java-examples-0.8.1-WordCount.jar file://`pwd`/hamlet.txt file://`pwd`/wordcount-result.txt"
-
-
-
+ - git fetch origin $TRAVIS_BRANCH:travis_pr_branch
+ - flake8-diff travis_pr_branch
+ - cd core && tox -e $TOXENV_CORE
+env:
+ - TOXENV_CORE=py27

ansible/README.md

@@ -69,9 +69,6 @@ There are four (4) roles and five (5) playbooks. These are:
 - Downloads and installs Apache Flink on master node.
 - Starts and Apache Flink, Yarn session.
 
-
-
-
 ## How to deploy
 
 You can deploy the whole cluster by running the cluster-install playbook:

ansible/hosts

+[master]
+snf-669832.vm.okeanos.grnet.gr
+
+[slaves]
+snf-669833.vm.okeanos.grnet.gr
+snf-669834.vm.okeanos.grnet.gr

ansible/playbooks/initialize.yml

+---
+
+  - hosts: master
+    user: root
+    gather_facts: no
+    roles:
+      - wait_for_ssh
+
+  - hosts: master
+    user: root
+    roles:
+      - proxy

ansible/roles/apache-flink/tasks/master.yml

@@ -24,7 +24,7 @@
     template: src=flink-init.j2 dest=/etc/init.d/flink-init owner=flink group=lambda mode=0740
 
   - name: Start Apache Flink.
-    shell: /etc/init.d/flink-init start > /dev/null &
+    shell: /etc/init.d/flink-init start > /dev/null
     tags:
       - start
 

ansible/roles/apache-flink/templates/flink-init.j2

@@ -9,6 +9,10 @@ SCRIPT_USER=flink
 # The path where Apache Flink is installed.
 INSTALLATION_PATH="{{ installation_path }}"
 
+# The full path of the pid file to use. Apache Flink is run as an Apache Yarn application. The id of this application
+# is stored on this file.
+APPLICATION_ID="$INSTALLATION_PATH/flink/flink.pid"
+
 # The full path of the lock file to use.
 LOCKFILE="$INSTALLATION_PATH/flink/flink-lock"
 
@@ -20,15 +24,50 @@ START_COMMAND="$INSTALLATION_PATH/flink/bin/yarn-session.sh -n {{ number_of_task
 STOP_COMMAND="$HADOOP_HOME/bin/yarn application --kill"
 
 start(){
+  # Assert that there is no other Apache Flink instance, created with this script, running.
+  [ -f $LOCKFILE ] && return 0
+
+  # Execute the command to start Apache Flink.
   sudo -E -u $SCRIPT_USER nohup $START_COMMAND > /dev/null &
+
+  # Get the returned value and create a lock file to prevent multiple instantiations.
   RETVAL=$?
   [ $RETVAL -eq 0 ] && $(sudo -u $SCRIPT_USER touch $LOCKFILE)
+
+  # Wait for a minute Apache Flink to start. The condition check whether an application under user "flink" has been
+  # started on Apache Yarn and whether a minute has passed.
+  i=0
+  while [ "$(sudo -u $SCRIPT_USER $HADOOP_HOME/bin/yarn application --list | cut -f4 | grep "flink")" == "" ] && [ $i -lt 6 ]
+  do
+    sleep 10
+    i=$((i+1))
+  done
+
+  # Save the application id of this Apache Flink application.
+  $(sudo -u $SCRIPT_USER $HADOOP_HOME/bin/yarn application --list | cut -f1,4 | grep "flink" | cut -f1 > $APPLICATION_ID)
+  chown $SCRIPT_USER $APPLICATION_ID
+  chmod 644 $APPLICATION_ID
+
   return $RETVAL
 }
 
 stop(){
-  id=$(sudo -u $SCRIPT_USER $HADOOP_HOME/bin/yarn application --list | grep "Flink session" | cut -f1)
-  sudo -E -u $SCRIPT_USER nohup $STOP_COMMAND $id > /dev/null &
+  # Assert that an Apache Flink instance, created with this script, is running.
+  [ ! -f $LOCKFILE ] && return 0
+
+  # Read the application id and execute the command to stop Apache Flink. The command will block
+  # until the service has been stopped.
+  id=$(sudo -u $SCRIPT_USER cat $APPLICATION_ID)
+  sudo -E -u $SCRIPT_USER $STOP_COMMAND $id > /dev/null
+
+  # Delete the files on Apache HDFS created when Apache Flink was started.
+  # These files are created by Apache Yarn to distribute Flink accross all nodes.
+  sudo -u $SCRIPT_USER $HADOOP_HOME/bin/hadoop fs -rm -r -skipTrash /user/flink/.flink/$id
+
+  # Delete application id file.
+  sudo -u $SCRIPT_USER rm $APPLICATION_ID
+
+  # Get the returned value of the executed command and remove the lock file.
   RETVAL=$?
   [ $RETVAL -eq 0 ] && $(sudo -u $SCRIPT_USER rm -f $LOCKFILE)
   return $RETVAL
@@ -55,6 +94,7 @@ case "$1" in
     [ -f $LOCKFILE ] && restart || :
     ;;
   status)
+    # If the lock file exists, then Apache Flink is running.
     [ -f $LOCKFILE ] && echo "Apache Flink is running." || echo "Apache Flink is not running."
     RETVAL=$?
     ;;

ansible/roles/apache-hadoop/tasks/master.yml

@@ -11,7 +11,7 @@
       - format-hdfs
 
   - name: Start Apache HDFS.
-    shell: /etc/init.d/hdfs-init start > /dev/null &
+    shell: /etc/init.d/hdfs-init start > /dev/null
     tags:
       - start-hdfs
 
@@ -21,7 +21,7 @@
       - start-hdfs
 
   - name: Start Apache Yarn.
-    shell: /etc/init.d/yarn-init start > /dev/null &
+    shell: /etc/init.d/yarn-init start > /dev/null
     tags:
       - start-yarn
 

ansible/roles/apache-hadoop/tasks/setup.yml

@@ -18,8 +18,13 @@
   - name: Configure core.
     template: src=core-site.xml.j2 dest="{{ installation_path }}/hadoop/etc/hadoop/core-site.xml" owner=hduser group=lambda mode=0644
 
-  - name: Configure Apache HDFS.
-    template: src=hdfs-site.xml.j2 dest="{{ installation_path }}/hadoop/etc/hadoop/hdfs-site.xml" backup=no owner=hduser group=lambda mode=0644
+  - name: Configure Apache HDFS for master node.
+    template: src=hdfs-site-master.xml.j2 dest="{{ installation_path }}/hadoop/etc/hadoop/hdfs-site.xml" backup=no owner=hduser group=lambda mode=0644
+    when: "'master' in group_names"
+
+  - name: Configure Apache HDFS for slave nodes.
+    template: src=hdfs-site-slave.xml.j2 dest="{{ installation_path }}/hadoop/etc/hadoop/hdfs-site.xml" backup=no owner=hduser group=lambda mode=0644
+    when: "'slaves' in group_names"
 
   - name: Configure Apache Yarn.
     template: src=yarn-site.xml.j2 dest="{{ installation_path }}/hadoop/etc/hadoop/yarn-site.xml" owner=hduser group=lambda mode=0644

ansible/roles/apache-hadoop/templates/core-site.xml.j2

@@ -18,7 +18,7 @@
 
 <configuration>
   <property>
-    <name>fs.default.name</name>
+    <name>fs.defaultFS</name>
     <value>hdfs://{{ groups.master | replace("[","") | replace("'","") | replace("]","") | replace(".vm.okeanos.grnet.gr",".local") }}:9000</value>
   </property>
   <property>

ansible/roles/apache-hadoop/templates/hdfs-init.j2

@@ -19,14 +19,26 @@ START_COMMAND="$INSTALLATION_PATH/hadoop/sbin/start-dfs.sh"
 STOP_COMMAND="$INSTALLATION_PATH/hadoop/sbin/stop-dfs.sh"
 
 start(){
-  sudo -u $SCRIPT_USER nohup $START_COMMAND > /dev/null &
+  # Assert that there is no other Apache HDFS instance, created with this script, running.
+  [ -f $LOCKFILE ] && return 0
+
+  # Execute the command to start Apache HDFS. The command waits until HDFS has been started.
+  sudo -u $SCRIPT_USER $START_COMMAND > /dev/null
+
+  # Get the returned value of the executed command and create a lock file to prevent multiple instantiations.
   RETVAL=$?
   [ $RETVAL -eq 0 ] && $(sudo -u $SCRIPT_USER touch $LOCKFILE)
   return $RETVAL
 }
 
 stop(){
-  sudo -u $SCRIPT_USER nohup $STOP_COMMAND > /dev/null &
+  # Assert that an Apache HDFS instance, created with this script, is running.
+  [ ! -f $LOCKFILE ] && return 0
+
+  # Execute the command to stop Apache HDFS. The command waits until HDFS has been stopped.
+  sudo -u $SCRIPT_USER $STOP_COMMAND > /dev/null
+
+  # Get the returned value of the executed command and delete the lock file.
   RETVAL=$?
   [ $RETVAL -eq 0 ] && $(sudo -u $SCRIPT_USER rm -f $LOCKFILE)
   return $RETVAL
@@ -53,6 +65,7 @@ case "$1" in
     [ -f $LOCKFILE ] && restart || :
     ;;
   status)
+    # If the lock file exists, then Apache HDFS is running.
     [ -f $LOCKFILE ] && echo "Apache HDFS is running." || echo "Apache HDFS is not running."
     RETVAL=$?
     ;;

ansible/roles/apache-hadoop/templates/hdfs-site.xml.j2 → ansible/roles/apache-hadoop/templates/hdfs-site-master.xml.j2

@@ -25,4 +25,8 @@
      <name>dfs.permissions</name>
      <value>false</value>
    </property>
+   <property>
+     <name>dfs.namenode.name.dir</name>
+     <value>file://{{ installation_path }}/hadoop/hdfs/name</value>
+   </property>
 </configuration>

ansible/roles/apache-hadoop/templates/hdfs-site-slave.xml.j2

+<?xml version="1.0" encoding="UTF-8"?>
+<?xml-stylesheet type="text/xsl" href="configuration.xsl"?>
+<!--
+  Licensed under the Apache License, Version 2.0 (the "License");
+  you may not use this file except in compliance with the License.
+  You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+  Unless required by applicable law or agreed to in writing, software
+  distributed under the License is distributed on an "AS IS" BASIS,
+  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+  See the License for the specific language governing permissions and
+  limitations under the License. See accompanying LICENSE file.
+-->
+
+<!-- Put site-specific property overrides in this file. -->
+
+<configuration>
+   <property>
+     <name>dfs.replication</name>
+     <value>{{ dfs_replication }}</value>
+   </property>
+   <property>
+     <name>dfs.permissions.enabled</name>
+     <value>false</value>
+   </property>
+   <property>
+     <name>dfs.datanode.data.dir</name>
+     <value>file://{{ installation_path }}/hadoop/hdfs/data</value>
+   </property>
+</configuration>

ansible/roles/apache-hadoop/templates/yarn-init.j2

@@ -19,14 +19,26 @@ START_COMMAND="$INSTALLATION_PATH/hadoop/sbin/start-yarn.sh"
 STOP_COMMAND="$INSTALLATION_PATH/hadoop/sbin/stop-yarn.sh"
 
 start(){
-  sudo -u $SCRIPT_USER nohup $START_COMMAND > /dev/null &
+  # Assert that there is no other Apache Yarn instance, created with this script, running.
+  [ -f $LOCKFILE ] && return 0
+
+  # Execute the command to start Apache Yarn. The command waits until Yarn has been started.
+  sudo -u $SCRIPT_USER $START_COMMAND > /dev/null
+
+  # Get the returned value of the executed command and create a lock file to prevent multiple instantiations.
   RETVAL=$?
   [ $RETVAL -eq 0 ] && $(sudo -u $SCRIPT_USER touch $LOCKFILE)
   return $RETVAL
 }
 
 stop(){
-  sudo -u $SCRIPT_USER nohup $STOP_COMMAND > /dev/null &
+  # Assert that an Apache Yarn instance, created with this script, is running.
+  [ ! -f $LOCKFILE ] && return 0
+
+  # Execute the command to stop Apache Yarn. The command waits until Yarn has been stopped.
+  sudo -u $SCRIPT_USER $STOP_COMMAND > /dev/null
+
+  # Get the returned value of the executed command and delete the lock file.
   RETVAL=$?
   [ $RETVAL -eq 0 ] && $(sudo -u $SCRIPT_USER rm -f $LOCKFILE)
   return $RETVAL
@@ -53,6 +65,7 @@ case "$1" in
     [ -f $LOCKFILE ] && restart || :
     ;;
   status)
+    # If the lock file exists, then Apache Yarn is running.
     [ -f $LOCKFILE ] && echo "Apache Yarn is running." || echo "Apache Yarn is not running."
     RETVAL=$?
     ;;

ansible/roles/apache-kafka/tasks/master.yml

@@ -11,7 +11,7 @@
       - configure-kafka
 
   - name: Start Apache Zookeeper server.
-    shell: /etc/init.d/zookeeper-init start > /dev/null &
+    shell: /etc/init.d/zookeeper-init start > /dev/null
     tags:
       - start-zookeeper
 
@@ -21,7 +21,7 @@
       - start-zookeeper
 
   - name: Start Apache Kafka server.
-    shell: /etc/init.d/kafka-init start > /dev/null &
+    shell: /etc/init.d/kafka-init start > /dev/null
     tags:
       - start-kafka
 

ansible/roles/apache-kafka/templates/kafka-init.j2

@@ -16,14 +16,26 @@ LOCKFILE="$INSTALLATION_PATH/kafka/kafka-lock"
 START_COMMAND="$INSTALLATION_PATH/kafka/bin/kafka-server-start.sh $INSTALLATION_PATH/kafka/config/server.properties"
 
 start(){
-  sudo -u $SCRIPT_USER /sbin/start-stop-daemon --start --background --make-pidfile --pidfile $PIDFILE --exec $START_COMMAND
+  # Assert that there is no other Apache Kafka instance, created with this script, running.
+  [ -f $LOCKFILE ] && return 0
+
+  # Execute the command to start Apache Kafka and wait until the service has been started.
+  sudo -u $SCRIPT_USER /sbin/start-stop-daemon --start --background --make-pidfile --pidfile $PIDFILE --exec $START_COMMAND --retry 5
+
+  # Get the returned value of the executed command and create a lock file to prevent multiple instantiations.
   RETVAL=$?
   [ $RETVAL -eq 0 ] && $(sudo -u $SCRIPT_USER touch $LOCKFILE)
   return $RETVAL
 }
 
 stop(){
-  sudo -u $SCRIPT_USER  /sbin/start-stop-daemon --stop --remove-pidfile --pidfile $PIDFILE
+  # Assert that an Apache Kafka instance, created with this script, is running.
+  [ ! -f $LOCKFILE ] && return 0
+
+  # Execute the command to stop Apache Kafka and wait until the service has been stopped.
+  sudo -u $SCRIPT_USER  /sbin/start-stop-daemon --stop --remove-pidfile --pidfile $PIDFILE --retry 5
+
+  # Get the returned value of the executed command and delete the lock file.
   RETVAL=$?
   [ $RETVAL -eq 0 ] && $(sudo -u $SCRIPT_USER rm -f $LOCKFILE)
   return $RETVAL
@@ -50,6 +62,7 @@ case "$1" in
     [ -f $LOCKFILE ] && restart || :
     ;;
   status)
+    # If the lock file exists, then Apache Kafka is running.
     [ -f $LOCKFILE ] && echo "Apache Kafka is running." || echo "Apache kafka is not running."
     RETVAL=$?
     ;;

ansible/roles/apache-kafka/templates/zookeeper-init.j2

@@ -16,14 +16,26 @@ LOCKFILE="$INSTALLATION_PATH/kafka/zookeeper-lock"
 START_COMMAND="$INSTALLATION_PATH/kafka/bin/zookeeper-server-start.sh $INSTALLATION_PATH/kafka/config/zookeeper.properties"
 
 start(){
-  sudo -u $SCRIPT_USER /sbin/start-stop-daemon --start --background --make-pidfile --pidfile $PIDFILE --exec $START_COMMAND
+  # Assert that there is no other Apache Zookeeper instance, created with this script, running.
+  [ -f $LOCKFILE ] && return 0
+
+  # Execute the command to start Apache Zookeeper and wait until the service has been started.
+  sudo -u $SCRIPT_USER /sbin/start-stop-daemon --start --background --make-pidfile --pidfile $PIDFILE --exec $START_COMMAND --retry 5
+
+  # Get the returned value of the executed command and create a lock file to prevent multiple instantiations.
   RETVAL=$?
   [ $RETVAL -eq 0 ] && $(sudo -u $SCRIPT_USER touch $LOCKFILE)
   return $RETVAL
 }
 
 stop(){
-  sudo -u $SCRIPT_USER /sbin/start-stop-daemon --stop --remove-pidfile --pidfile $PIDFILE
+  # Assert that an Apache Zookeeper instance, created with this script, is running.
+  [ ! -f $LOCKFILE ] && return
+
+  # Execute the command to stop Apache Zookeeper and wait until the service has been stopped.
+  sudo -u $SCRIPT_USER /sbin/start-stop-daemon --stop --remove-pidfile --pidfile $PIDFILE --retry 5
+
+  # Get the returned value of the executed command and delete the lock file.
   RETVAL=$?
   [ $RETVAL -eq 0 ] && $(sudo -u $SCRIPT_USER rm -f $LOCKFILE)
   return $RETVAL
@@ -50,6 +62,7 @@ case "$1" in
     [ -f $LOCKFILE ] && restart || :
     ;;
   status)
+    # If the lock file exists, then Apache Zookeeper is running.
     [ -f $LOCKFILE ] && echo "Apache Zookeeper is running." || echo "Apache Zookeeper is not running."
     RETVAL=$?
     ;;

ansible/roles/common/files/sources.list

+deb http://ftp.de.debian.org/debian/ jessie main
+deb-src http://ftp.de.debian.org/debian/ jessie main
+
+deb http://security.debian.org/ jessie/updates main
+deb-src http://security.debian.org/ jessie/updates main
+
+# jessie-updates, previously known as 'volatile'
+deb http://ftp.de.debian.org/debian/ jessie-updates main
+deb-src http://ftp.de.debian.org/debian/ jessie-updates main
+
+deb http://apt.dev.grnet.gr jessie/

ansible/roles/common/tasks/all.yml

----
-  - name: Create users for each application.
-    include: users.yml
-    when: "'slaves' in group_names"
-
-  - name: Include common tasks.
-    include: common-1.yml
-
-  - name: Include more common tasks.
-    include: common-2.yml

ansible/roles/common/tasks/common-1.yml

 ---
+  - name: Fix locale problem.
+    command: update-locale LANGUAGE="en_US.UTF-8" LC_ALL="en_US.UTF-8"
+
+  - name: Copy sources list.
+    copy: src=sources.list dest=/etc/apt/sources.list owner=root group=root mode=0640
 
   - name: Set hostname
     hostname: name={{ inventory_hostname | replace(".vm.okeanos.grnet.gr",".local") }}
@@ -30,3 +35,15 @@
 
   - name: Add kafka user to sudo group.
     user: name=kafka group=sudo
+
+  - name: Install supervisord with apt.
+    apt: name=supervisor state=latest
+    environment: proxy_env
+
+  - name: Configure supervisord for master.
+    template: src=supervisord-master.conf.j2 dest=/etc/supervisor/supervisord.conf owner=root group=root mode=0600
+    when: "'master' in group_names"
+
+  - name: Configure supervisord for slaves.
+    template: src=supervisord-slaves.conf.j2 dest=/etc/supervisor/supervisord.conf owner=root group=root mode=0600
+    when: "'slaves' in group_names"

ansible/roles/common/tasks/main.yml

@@ -5,7 +5,12 @@
     tags:
       - master
 
-  - name: Include tasks for all nodes.
-    include: all.yml
-    tags:
-      - all
+  - name: Create users for each application.
+    include: users.yml
+    when: "'slaves' in group_names"
+
+  - name: Include common tasks.
+    include: common-1.yml
+
+  - name: Include more common tasks.
+    include: common-2.yml

ansible/roles/common/tasks/master.yml

@@ -2,14 +2,6 @@
   - name: Create users for each application.
     include: users.yml
 
-#  - name: Generate ssh key for root.
-#    shell: cat /dev/zero | ssh-keygen -q -N ""
-#    args:
-#      creates: /root/.ssh/id_rsa.pub
-
-#  - name: Fetch id_rsa.pub file from root.
-#    fetch: src=/root/.ssh/id_rsa.pub dest=/tmp/fetched/root_id_rsa.pub flat=yes
-
   - name: Generate ssh key for hduser.
     shell: cat /dev/zero | ssh-keygen -q -N ""
     args:
@@ -34,3 +26,15 @@
 
   - name: Set up ssh config for flink user.
     template: src=ssh-config.j2 dest=/home/flink/.ssh/config owner=flink group=lambda mode=600
+
+  - name: Copy Lambda Instance init script.
+    template: src=lambda-init.j2 dest=/etc/init.d/lambda-init owner=root group=lambda mode=0740
+
+    # The Lambda services will be started individually during the execution of the playbooks.
+    # The lock file neends to be created so that lambda-init script is aware that there is
+    # a Lambda Instance running.
+  - name: Create Lambda Instance lock file.
+    file: path=/root/lambda-lock state=touch owner=root group=lambda mode=0640
+
+  - name: Put lambda init script on boot and shutdown sequence.
+    command: update-rc.d lambda-init defaults

ansible/roles/common/templates/lambda-init.j2

+#!/bin/bash
+
+# The full path of the lock file to use.
+LOCKFILE="/root/lambda-lock"
+
+start(){
+  # Assert that there is no other Lambda instance, created with this script, running.
+  [ -f $LOCKFILE ] && return 0
+
+  # Start Apache HDFS.
+  echo "Starting Apache HDFS..."
+  /etc/init.d/hdfs-init start
+  returnedValue=$?
+  if [ $returnedValue -eq 0 ]
+  then
+    echo "Apache HDFS has been started!"
+
+    # Force Apache HDFS to exit safe mode so that Apache Flink can be started later on this script.
+    {{ hadoop_home }}/bin/hdfs dfsadmin -safemode leave
+  else
+    echo "Apache HDFS has failed to start with returned code $returnedValue."
+  fi
+
+  # Start Apache Yarn.
+  echo "Starting Apache Yarn..."
+  /etc/init.d/yarn-init start
+  returnedValue=$?
+  if [ $returnedValue -eq 0 ]
+  then
+    echo "Apache Yarn has been started!"
+  else
+    echo "Apache Yarn has failed to start with returned code $returnedValue."
+  fi
+
+  # Start supervisord on master node.
+  echo "Starting Supervisord..."
+  supervisord -c /etc/supervisor/supervisord.conf --logfile=/root/supervisord.log
+  returnedValue=$?
+  if [ $returnedValue -eq 0 ]
+  then
+    echo "Supervisord on master node has been started!"
+  else
+    echo "Supervisord on master node has failed to start with returned code $returnedValue."
+  fi
+
+  # Start Apache Zookeeper.
+  echo "Starting Apache Zookeeper..."
+  supervisorctl start apache_zookeeper
+  # Wait for Apache Zookeeper to start.
+  while [ "$(supervisorctl status apache_zookeeper | tr -s ' ' | cut -f2 -d' ')" == "STARTING" ] 
+  do
+    sleep 10
+  done
+  apache_zookeeper_status=$(supervisorctl status apache_zookeeper | tr -s ' ' | cut -f2 -d' ')
+  if [ "$apache_zookeeper_status" != "RUNNING" ]
+  then
+    echo "Apache Zookeeper has failed to start with code $apache_zookeeper_status."
+  else
+    echo "Apache Zookeeper has been started!"
+  fi
+
+  # Start Apache Kafka on master node.
+  echo "Starting Apache kafka..."
+  supervisorctl start apache_kafka
+  # Wait for Apache Kafka to start.
+  while [ "$(supervisorctl status apache_kafka | tr -s ' ' | cut -f2 -d' ')" == "STARTING" ] 
+  do
+    sleep 10
+  done
+  apache_kafka_status=$(supervisorctl status apache_kafka | tr -s ' ' | cut -f2 -d' ')
+  if [ "$apache_kafka_status" != "RUNNING" ]
+  then
+    echo "Apache kafka has failed to start with code $apache_kafka_status."
+  else
+    echo "Apache kafka has been started!"
+  fi
+
+  # Start Apache Kafka on each slave node.
+  for node in $(cat /etc/hosts | grep "snf" | cut -f2)
+  do
+    if [ "$node" == "$(hostname).local" ]
+    then
+      continue
+    fi
+    echo "Starting Apache Kafka at $node..."
+    ssh -l root $node supervisord -c /etc/supervisor/supervisord.conf --logfile=/root/supervisord.log
+    echo "Supervisord on $node has been started!"
+    ssh -l root $node supervisorctl start apache_kafka
+   # Wait for Apache kafka to start.
+   while [ "$(ssh -l root $node supervisorctl status apache_kafka | tr -s ' ' | cut -f2 -d' ')" == "STARTING" ]