RHEL 8 New Features for Experienced Linux Administrators
Performance Checklist
In this lab you will enable a module stream and install packages from it, accessing the server through the web console interface, then run an Ansible Playbook that uses a RHEL System Role to ensure further configuration is correct on the server.
Outcomes
You should be able to:
Enable and use the web console to provide system access.
Enable module streams and install packages.
Use the
rhel-system-roles.postfixrole to install and configure Postfix.
Log in to workstation as student using student as the password.
On workstation, run the lab tools-review start command to verify that the environment is ready and prepare the systems for the exercise.
[student@workstation ~]$lab tools-review start
Note
In case workstation hangs using the web console, restart the virtual machine, and log into the web console with a new browser.
Use the web console to access
serveraand Yum to enable the Python 3.6 module stream.On
workstation, open Firefox and navigate tohttps://servera.lab.example.com:9090. If a certificate error appears, accept the self-signed certificate.Check Reuse my password for privileged tasks and sign in using
studentas user name andstudentas the password.Click on
servera.lab.example.comin the left navigation bar and select the Terminal menu entry on the left.Use the yum module list command to list available streams, and choose the one for Python 3.6.
[student@servera ~]$sudo yum module listUse the yum module install python36 command to install the Python 3.6 module.
[student@servera ~]$sudo yum module install python36
Using Red Hat Enterprise Linux Roles on
workstation, create a playbook namedlab-postfix.ymlwithin the working directory of~/lab-roles. Include the directivebecome: yesto enable sudo usage and configureserverato be a Postfix MTA, using the following role configuration variables:Variable Value inet_interfacesallmyorigin$mydomainmydestination$myhostname localhost.$mydomain $mydomainrelay_domains$mydestinationrelay_hostexample.comChange to the
/home/student/lab-rolesworking directory.[student@workstation ~]$cd ~/lab-roles[student@workstation lab-roles]$Create a playbook,
lab-postfix.yml, with one play that targetsservera.lab.example.com. Include therhel-system-roles.postfixrole in therolessection of the play.The contents of the
lab-postfix.ymlnow matches:--- - hosts: servera.lab.example.com become: yes vars: postfix_conf: inet_interfaces: "all" myorigin: "$mydomain" mydestination: "$myhostname localhost.$mydomain $mydomain" relay_domains: "$mydestination" relay_host: "example.com" roles: - rhel-system-roles.postfixRun the playbook.
[student@workstation lab-roles]$ansible-playbook lab-postfix.ymlPLAY [all] ********************************************************************* TASK [Gathering Facts] ********************************************************* ok: [servera.lab.example.com] TASK [rhel-system-roles.postfix : Install Postfix] ***************************** changed: [servera.lab.example.com] ...output omitted... TASK [rhel-system-roles.postfix : Configure Postfix] *************************** changed: [servera.lab.example.com] => (item={'key': 'inet_interface', 'value': 'all'}) changed: [servera.lab.example.com] => (item={'key': 'myorigin', 'value': '$mydomain'}) changed: [servera.lab.example.com] => (item={'key': 'mydestination', 'value': '$myhostname localhost.$mydomain $mydomain'}) changed: [servera.lab.example.com] => (item={'key': 'relay_domains', 'value': '$mydestination'}) changed: [servera.lab.example.com] => (item={'key': 'relay_host', 'value': 'example.com'}) RUNNING HANDLER [rhel-system-roles.postfix : check postfix] ******************** changed: [servera.lab.example.com] RUNNING HANDLER [rhel-system-roles.postfix : restart postfix] ****************** changed: [servera.lab.example.com] PLAY RECAP ********************************************************************* servera.lab.example.com : ok=9 changed=8 unreachable=0 failed=0Use telnet servera.lab.example.com 25 on
workstationto test mail server functionality.[student@workstation ~]$telnet servera.lab.example.com 25Connected to servera.lab.example.com. Escape character is '^]'. 220 servera.lab.example.com ESMTP Postfix ^] telnet> quit Connection closed.
