Chapter 3. Monitoring performance using RHEL System Roles

Procedure

1. Install the rhel-system-roles package on the system that you want to use as a control node:

   # dnf install rhel-system-roles

2. Install the Ansible Core package:

   # dnf install ansible-core

Procedure

1. Create the required Ansible inventory containing the hosts and groups that you want to manage. Here is an example using a file called inventory.ini of a group of hosts called webservers:

   [webservers]
   host1
   host2
   host3

2. Create an Ansible playbook including the required role. The following example shows how to use roles through the roles: option for a playbook:

   The following example shows how to use roles through the roles: option for a given play:

   ---
   - hosts: webservers
     roles:
   
        - rhel-system-roles.network
        - rhel-system-roles.postfix

   Note

   Every role includes a README file, which documents how to use the role and supported parameter values. You can also find an example playbook for a particular role under the documentation directory of the role. Such documentation directory is provided by default with the rhel-system-roles package, and can be found in the following location:

   /usr/share/doc/rhel-system-roles/SUBSYSTEM/

   Replace SUBSYSTEM with the name of the required role, such as postfix, metrics, network, tlog, or ssh.

3. To execute the playbook on specific hosts, you must perform one of the following:

   • Edit the playbook to use hosts: host1[,host2,…​], or hosts: all, and execute the command:

     # ansible-playbook name.of.the.playbook

   • Edit the inventory to ensure that the hosts you want to use are defined in a group, and execute the command:

     # ansible-playbook -i name.of.the.inventory name.of.the.playbook

   • Specify all hosts when executing the ansible-playbook command:

     # ansible-playbook -i host1,host2,... name.of.the.playbook

     Important

     Be aware that the -i flag specifies the inventory of all hosts that are available. If you have multiple targeted hosts, but want to select a host against which you want to run the playbook, you can add a variable in the playbook to be able to select a host. For example:

     Ansible Playbook | example-playbook.yml:
     
     
     - hosts: "{{ target_host }}"
       roles:
          - rhel-system-roles.network
          - rhel-system-roles.postfix

     Playbook execution command:

     # ansible-playbook -i host1,..hostn -e target_host=host5 example-playbook.yml

Procedure

1. Configure localhost in the the /etc/ansible/hosts Ansible inventory by adding the following content to the inventory:

   localhost ansible_connection=local

2. Create an Ansible playbook with the following content:

   ---
   - hosts: localhost
     vars:
       metrics_graph_service: yes
     roles:
       - rhel-system-roles.metrics

3. Run the Ansible playbook:

   # ansible-playbook name_of_your_playbook.yml

   Note

   Since the metrics_graph_service boolean is set to value="yes", Grafana is automatically installed and provisioned with pcp added as a data source.

4. To view visualization of the metrics being collected on your machine, access the grafana web interface as described in Accessing the Grafana web UI.

Procedure

1. Add the name or IP of the machines you wish to monitor via the playbook to the /etc/ansible/hosts Ansible inventory file under an identifying group name enclosed in brackets:

   [remotes]
   webserver.example.com
   database.example.com

2. Create an Ansible playbook with the following content:

   ---
   - hosts: remotes
     vars:
       metrics_retention_days: 0
     roles:
       - rhel-system-roles.metrics

3. Run the Ansible playbook:

   # ansible-playbook name_of_your_playbook.yml -k

Procedure

1. Create an Ansible playbook with the following content:

   ---
   - hosts: localhost
     vars:
       metrics_graph_service: yes
       metrics_query_service: yes
       metrics_retention_days: 10
       metrics_monitored_hosts: ["database.example.com", "webserver.example.com"]
     roles:
       - rhel-system-roles.metrics

2. Run the Ansible playbook:

   # ansible-playbook name_of_your_playbook.yml

   Note

   Since the metrics_graph_service and metrics_query_service booleans are set to value="yes", grafana is automatically installed and provisioned with pcp added as a data source with the pcp data recording indexed into redis, allowing the pcp querying language to be used for complex querying of the data.

3. To view graphical representation of the metrics being collected centrally by your machine and to query the data, access the grafana web interface as described in Accessing the Grafana web UI.

Procedure

1. Include the following variables in the Ansible playbook you want to setup authentication for:

   ---
     vars:
       metrics_username: your_username
       metrics_password: your_password

2. Run the Ansible playbook:

   # ansible-playbook name_of_your_playbook.yml

Procedure

1. Configure localhost in the the /etc/ansible/hosts Ansible inventory by adding the following content to the inventory:

   localhost ansible_connection=local

2. Create an Ansible playbook that contains the following content:

   ---
   - hosts: localhost
     roles:
       - role: rhel-system-roles.metrics
         vars:
           metrics_from_mssql: yes

3. Run the Ansible playbook:

   # ansible-playbook name_of_your_playbook.yml