slaves.yml

- hosts: slaves
  tasks:
        - name: Update hdfs-site.xml file
          blockinfile:
                path: /etc/hadoop/hdfs-site.xml 
                insertafter: "<configuration>"
                block: |
                        <property>
                        <name>dfs.data.dir</name>
                        <value>/data</value>
                        </property>
                state: present

        - name: Update core-site.xml file
          blockinfile:
                path: /etc/hadoop/core-site.xml
                insertafter: "<configuration>"
                block: |
                        <property>
                        <name>fs.default.name</name>
                        <value>hdfs://{{ groups['master'][0] }}:9001</value>
                        </property>

        - name: Updating mapred-site.xml file
          blockinfile:
                path: /etc/hadoop/mapred-site.xml
                insertafter: "<configuration>"
                block: |
                        <property>
                        <name>mapred.job.tracker</name>
                        <value>{{ groups['jobtracker'][0] }}:9002</value>
                        </property>

        - name: Allowing specific ports for datanode and tasktracker
          firewalld:
                port: "{{ item }}"
                state: enabled
                immediate: yes
                permanent: yes      
          with_items:
                - "9001/tcp"
                - "50070/tcp"
                - "50075/tcp"
                - "50475/tcp"
                - "50010/tcp"
                - "1022/tcp"
                - "50020/tcp"
                - "1019/tcp"
                - "9002/tcp"
                - "50060/tcp"

        - name: Starting the datanode and tasktracker services
          command: "{{ item }}"
          with_items:
                - hadoop-daemon.sh start datanode
                - hadoop-daemon.sh start tasktracker