Red Hat Enterprise Linux Automation with Ansible
In this exercise, you will explore how to use host patterns to specify hosts from the inventory for plays or ad hoc commands. You will be provided with several example inventories to explore host patterns.
Outcomes
You will be able to use different host patterns to access various hosts in an inventory.
Log in to workstation as student using student as the password.
On workstation, run the lab projects-host start command. The script creates the projects-host project directory, and then downloads the Ansible configuration file and the host inventory file needed for this exercise.
[student@workstation ~]$lab projects-host start
Procedure 6.1. Instructions
On
workstation, change to the working directory for the exercise,/home/student/projects-host, and review the contents of the directory.[student@workstation ~]$cd ~/projects-host[student@workstation projects-host]$List the contents of the directory.
[student@workstation projects-host]$lsansible.cfg inventory1 inventory2 playbook.ymlInspect the example inventory file,
inventory1. Notice how the inventory is organized. Explore which hosts and groups are in the inventory, and which domains are used.srv1.example.com srv2.example.com s1.lab.example.com s2.lab.example.com [web] jupiter.lab.example.com saturn.example.com [db] db1.example.com db2.example.com db3.example.com [lb] lb1.lab.example.com lb2.lab.example.com [boston] db1.example.com jupiter.lab.example.com lb2.lab.example.com [london] db2.example.com db3.example.com file1.lab.example.com lb1.lab.example.com [dev] web1.lab.example.com db3.example.com [stage] file2.example.com db2.example.com [prod] lb2.lab.example.com db1.example.com jupiter.lab.example.com [function:children] web db lb city [city:children] boston london environments [environments:children] dev stage prod new [new] 172.25.252.23 172.25.252.44 172.25.252.32
Inspect the example inventory file,
inventory2. Notice how the inventory is organized. Explore which hosts and groups are in the inventory, and which domains are used.workstation.lab.example.com [london] servera.lab.example.com [berlin] serverb.lab.example.com [tokyo] serverc.lab.example.com [atlanta] serverd.lab.example.com [europe:children] london berlin
Lastly, inspect the contents of the playbook,
playbook.yml. Notice how the playbook uses thedebugmodule to display the name of each managed host.--- - name: Resolve host patterns hosts: tasks: - name: Display managed host name debug: msg: "{{ inventory_hostname }}"
Using an ad hoc command, determine if the
db1.example.comserver is present in theinventory1inventory file.[student@workstation projects-host]$ansible db1.example.com -i inventory1 \>--list-hostshosts (1): db1.example.comUsing an ad hoc command, reference an IP address contained in the
inventory1inventory with a host pattern.[student@workstation projects-host]$ansible 172.25.252.44 -i inventory1 \>--list-hostshosts (1): 172.25.252.44With an ad hoc command, use the
allgroup to list all managed hosts in theinventory1inventory file.[student@workstation projects-host]$ansible all -i inventory1 --list-hostshosts (17): srv1.example.com srv2.example.com s1.lab.example.com s2.lab.example.com jupiter.lab.example.com saturn.example.com db1.example.com db2.example.com db3.example.com lb1.lab.example.com lb2.lab.example.com file1.lab.example.com web1.lab.example.com file2.example.com 172.25.252.23 172.25.252.44 172.25.252.32With an ad hoc command, use the asterisk (*) character to list all hosts that end in
.example.comin theinventory1inventory file.[student@workstation projects-host]$ansible '*.example.com' -i inventory1 \>--list-hostshosts (14): jupiter.lab.example.com saturn.example.com db1.example.com db2.example.com db3.example.com lb1.lab.example.com lb2.lab.example.com file1.lab.example.com web1.lab.example.com file2.example.com srv1.example.com srv2.example.com s1.lab.example.com s2.lab.example.comAs you can see in the output of the preceeding command, there are 14 hosts in the
*.example.comdomain. Modify the host pattern in the previous ad hoc command so that hosts in the*.lab.example.comdomain are ignored.[student@workstation projects-host]$ansible '*.example.com, !*.lab.example.com' \>-i inventory1 --list-hostshosts (7): saturn.example.com db1.example.com db2.example.com db3.example.com file2.example.com srv1.example.com srv2.example.comWithout accessing the groups in the
inventory1inventory file, use an ad hoc command to list these three hosts:lb1.lab.example.com,s1.lab.example.com, anddb1.example.com.[student@workstation projects-host]$ansible \>lb1.lab.example.com,s1.lab.example.com,db1.example.com -i inventory1 \>--list-hostshosts (3): lb1.lab.example.com s1.lab.example.com db1.example.comUse a wildcard host pattern in an ad hoc command to list hosts that start with a
172.25.IP address in theinventory1inventory file.[student@workstation projects-host]$ansible '172.25.*' -i inventory1 --list-hostshosts (3): 172.25.252.23 172.25.252.44 172.25.252.32Use a host pattern in an ad hoc command to list all hosts in the
inventory1inventory file that start with the letter "s."[student@workstation projects-host]$ansible 's*' -i inventory1 --list-hostshosts (7): saturn.example.com srv1.example.com srv2.example.com s1.lab.example.com s2.lab.example.com file2.example.com db2.example.comNotice the
file2.example.comanddb2.example.comhosts in the output of the preceding command. They appear in the list because they are both members of a group calledstage, which also begins with the letter "s."Using a list and wildcard host patterns in an ad hoc command, list all hosts in the
inventory1inventory in theprodgroup, those hosts with an IP address beginning with172, and hosts that containlabin their name.[student@workstation projects-host]$ansible 'prod,172*,*lab*' -i inventory1 \>--list-hostshosts (11): lb2.lab.example.com db1.example.com jupiter.lab.example.com 172.25.252.23 172.25.252.44 172.25.252.32 lb1.lab.example.com file1.lab.example.com web1.lab.example.com s1.lab.example.com s2.lab.example.comUse an ad hoc command to list all hosts that belong to both the
dbandlondongroups.[student@workstation projects-host]$ansible 'db,&london' -i inventory1 \>--list-hostshosts (2): db2.example.com db3.example.comModify the
hostsvalue in theplaybook.ymlfile so that all servers in thelondongroup are targeted. Execute the playbook using theinventory2inventory file....output omitted... hosts:
london...output omitted...[student@workstation projects-host]$ansible-playbook -i inventory2 playbook.yml...output omitted... TASK [Gathering Facts] ************************************************ ok: [servera.lab.example.com] ...output omitted...Modify the
hostsvalue in theplaybook.ymlfile so that all servers in theeuropenested group are targeted. Execute the playbook using theinventory2inventory file....output omitted... hosts:
europe...output omitted...[student@workstation projects-host]$ansible-playbook -i inventory2 playbook.yml...output omitted... TASK [Gathering Facts] ************************************************ ok: [servera.lab.example.com] ok: [serverb.lab.example.com] ...output omitted...Modify the
hostsvalue in theplaybook.ymlfile so that all servers that do not belong to any group are targeted. Execute the playbook using theinventory2inventory file....output omitted... hosts:
ungrouped...output omitted...[student@workstation projects-hosts]$ansible-playbook -i inventory2 playbook.yml...output omitted... TASK [Gathering Facts] ************************************************ ok: [workstation.lab.example.com] ...output omitted...
