3. Setup and Ad Hoc Commands
In this lab we’ll continue with our environment setup from Chapter 1 and learn how to run ad hoc commands.
Task 1
- Ping all nodes in the inventory file using the ping module.
Tip
You’ve used the ping module in a previous lab.Solution Task 1
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| $ ansible all -i hosts -m ping
5.102.146.128 | SUCCESS => {
"ansible_facts": {
"discovered_interpreter_python": "/usr/libexec/platform-python"
},
"changed": false,
"ping": "pong"
}
...
...
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Task 2
- Gather all facts from the nodes.
- Only gather the fact
ansible_default_ipv4 from all hosts.
Solution Task 2
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| $ ansible all -i hosts -m setup # (a lot of green output should be printed)
$ ansible all -i hosts -m setup -a "filter=ansible_default_ipv4"
5.102.146.204 | SUCCESS => {
"ansible_facts": {
"ansible_default_ipv4": {
"address": "5.102.146.204",
"alias": "eth0",
"broadcast": "5.102.146.255",
"gateway": "5.102.146.1",
"interface": "eth0",
"macaddress": "5a:42:05:66:92:cc",
"mtu": 1500,
"netmask": "255.255.255.0",
"network": "5.102.146.0",
"type": "ether"
},
"discovered_interpreter_python": "/usr/libexec/platform-python"
},
"changed": false
}
...
...
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Task 3
- Search through the online documentation for special (magical) variables.
- Which special variable could you use to set the
hostname on each of the servers using the information in the inventory file?
Solution Task 3
- See Ansible docs for special variables: Special Variables
inventory_hostname contains the name of the managed host from the inventory file and can be used to set the hostname on the servers.
Task 4
- Try to find an appropriate Ansible module to complete Task 3. Find out what parameters the module accepts.
- This module will try to make changes to the
/etc/hostname file. What options should you use with the ansible command to make that work?
Solution Task 4
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| $ ansible-doc -l | grep hostname # or see webpage
bigip_hostname Manage the hostname of a BIG-IP
hostname Manage hostname
win_hostname Manages local Windows computer name
$ ansible-doc -s hostname
- name: Manage hostname
hostname:
name: # (required) Name of the host
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- We will need root privileges and therefore we have to use the become option
-b
Task 5
- Set the hostname on all nodes using the inventory and an ansible ad hoc command.
- Check on all nodes if the hostname has been changed.
Solution Task 5
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| ansible all -i hosts -b -m hostname -a "name={{ inventory_hostname }}"
ansible all -i hosts -a "cat /etc/hostname"
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Task 6
Complete the next steps using Ansible ad hoc commands:
- Install
httpd on the nodes in group web - Start
httpd on the remote server and configure it to always start on boot. - Revert the changes made by the ad hoc commands again.
Solution Task 6
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| ansible web -i hosts -b -m dnf -a "name=httpd state=installed"
ansible web -i hosts -b -m service -a "name=httpd state=started enabled=yes"
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Reverting the changes made on the remote hosts:
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| ansible web -i hosts -b -m service -a "name=httpd state=stopped enabled=no"
ansible web -i hosts -b -m dnf -a "name=httpd state=absent"
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Task 7
Complete the next steps using ansible ad hoc commands:
- Create a file
/home/ansible/testfile.txt on node2. - Paste some custom text into the file using the
copy module. - Remove the file with an ad hoc command.
Solution Task 7
Possible solution 1:
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| ansible node2 -i hosts -m file -a "path=/home/ansible/testfile.txt state=touch"
ansible node2 -i hosts -m copy -a "dest=/home/ansible/testfile.txt content='SOME RANDOM TEXT'"
ansible node2 -i hosts -m file -a "path=/home/ansible/testfile.txt state=absent"
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Possible solution 2:
The copy module can create the file directly
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| ansible node2 -i hosts -m copy -a "dest=/home/ansible/testfile.txt content='SOME RANDOM TEXT'"
ansible node2 -i hosts -m file -a "path=/home/ansible/testfile.txt state=absent"
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All done?