Lesson 2.3: Running Adhoc Commands

Adhoc commands are like individual commands.
Ansible Commands are called Ansible Modules
-m : module
-a : argument

Syntax of Ad-hoc Command

anisble < hostgroup > -m < ansible module > -a '< arguements >'

Basic Example using ping module

[devops@serverA playbooks]$ ansible all -m ping
192.168.208.103 | SUCCESS => {
    "ansible_facts": {
        "discovered_interpreter_python": "/usr/bin/python3"
    },
    "changed": false,
    "ping": "pong"
}
192.168.208.104 | SUCCESS => {
    "ansible_facts": {
        "discovered_interpreter_python": "/usr/bin/python3"
    },
    "changed": false,
    "ping": "pong"
}
192.168.208.102 | SUCCESS => {
    "ansible_facts": {
        "discovered_interpreter_python": "/usr/bin/python3"
    },
    "changed": false,
    "ping": "pong"
}

Finding the right module name

Syntax: ansible-doc -l | grep < name >

[devops@serverA playbooks]$ ansible-doc -l | grep user | grep builtin
ansible.builtin.user

Taking help

Syntax: ansible-doc help < module_name >

[devops@serverA playbooks]$ ansible-doc help ansible.builtin.user

Creating a user using ansible

--become : Become as root / sudo previllages
-u [user_name] : Running as which user. The user defined will run the command in the managed hosts from the specified user. If you do not provide the username then, it will use the current user of the system of control host in managed host.

Color Indication
- Red - Failed / Command Failed.
- Yellow - Changed / Really the command executed.
- Green - Success / Has already performed this action previously.

# For all listed Managed Hosts
[devops@serverA playbooks]$ ansible all -m ansible.builtin.user -a "name=david" -u devops --become
 
# For only a group 
[devops@serverA playbooks]$ ansible testservers -m ansible.builtin.user -a 'name=testuser' --become

Another Method

Without using --become
Without using -u

# Modify the ansible.cfg file
[devops@serverA playbooks]$ vim ansible.cfg
 
[devops@serverA playbooks]$ cat ansible.cfg
[defaults]
inventory=/home/devops/playbooks/inventory
remote_user=devops
 
[privilege_escalation]
become=true
 
[devops@serverA playbooks]$ ansible testservers -m ansible.builtin.user -a 'name=testuser'

Idempotent Property: The actions that are already performed in a server, will not be executed. Shows green color output, with success status.

Removing a user

[devops@serverA playbooks]$ ansible testservers -m ansible.builtin.user -a 'name=testuser'

Modifying a user in all

# Modifying the uid of the user david
[devops@serverA playbooks]$ ansible all -m ansible.builtin.user -a 'name=david uid=3001'

Deploying web page on Apache Web Server Using Ansible Ad-Hoc Commands

# Modified inventory file, with added webservers 
[devops@serverA playbooks]$ cat inventory
[devservers]
192.168.208.102
 
[testservers]
192.168.208.103
 
[webservers]
192.168.208.104
 
[test:children]
testservers
 
[dev:children]
devservers
 
[web:children]
webservers
 
# Listing Hosts of Webservers 
[devops@serverA playbooks]$ ansible webservers --list-hosts
  hosts (1):
    192.168.208.104
 
# Finding Out the Module for YUM in ansible 
[devops@serverA playbooks]$ ansible-doc -l | grep yum
ansible.builtin.yum                                                                              Manages packages with the...
ansible.builtin.yum_repository                                                                   Add or r...
community.general.yum_versionlock                                                                Locks / unlocks a installed package(s) from being updated ...
 
# View the examples of the ansible.builtin.yum module 
[devops@serverA playbooks]$ ansible-doc help ansible.builtin.yum
 
# Install yum using ad-hoc command 
[devops@serverA playbooks]$ ansible webservers  -m ansible.builtin.yum -a "name=httpd state=latest"
192.168.208.104 | CHANGED => {
    "ansible_facts": {
        "discovered_interpreter_python": "/usr/bin/python3"
    },
    "changed": true,
    "msg": "",
    "rc": 0,
    "results": [
        "Installed: httpd-tools-2.4.62-1.el9.aarch64",
        "Installed: centos-logos-httpd-90.8-1.el9.noarch",
        "Installed: apr-util-openssl-1.6.1-23.el9.aarch64",
        "Installed: mod_lua-2.4.62-1.el9.aarch64",
        "Installed: httpd-2.4.62-1.el9.aarch64",
        "Installed: httpd-core-2.4.62-1.el9.aarch64",
        "Installed: apr-1.7.0-12.el9.aarch64",
        "Installed: httpd-filesystem-2.4.62-1.el9.noarch",
        "Installed: mod_http2-2.0.26-2.el9.aarch64",
        "Installed: apr-util-1.6.1-23.el9.aarch64",
        "Installed: apr-util-bdb-1.6.1-23.el9.aarch64"
    ]
}
 
# Testing in the original Server ~ For Reference 
[devops@serverD ~]# rpm -q httpd
package httpd is not installed
[devops@serverD ~]$ rpm -q httpd
httpd-2.4.62-1.el9.aarch64
 
# Start and Enable httpd service  
[devops@serverA playbooks]$ ansible webservers -m ansible.builtin.service -a 'name=httpd state=started'
[devops@serverA playbooks]$ ansible webservers -m ansible.builtin.service -a 'name=httpd enabled=yes'
 
# Testing in the original Server ~ For Reference 
# Before
[devops@serverD ~]$ systemctl status httpd
○ httpd.service - The Apache HTTP Server
     Loaded: loaded (/usr/lib/systemd/system/httpd.service; disabled; preset: disabled)
     Active: inactive (dead)
# After 
[devops@serverD ~]$ systemctl status httpd
● httpd.service - The Apache HTTP Server
     Loaded: loaded (/usr/lib/systemd/system/httpd.service; enabled; preset: disabled)
     Active: active (running) since Fri 2024-10-25 09:55:09 +0545; 2min 9s ago
 
# Adding firewall http 
[devops@serverA playbooks]$ ansible-doc -l | grep firewall
[devops@serverA playbooks]$ ansible-doc help ansible.posix.firewalld
 
# Testing in the Original Server ~ For Reference FIREWALLD
[devops@serverD ~]$ sudo firewall-cmd --list-all
public (active)
  target: default
  icmp-block-inversion: no
  interfaces: ens160
  sources:
  services: cockpit dhcpv6-client http ssh
  ports:
  protocols:
  forward: yes
  masquerade: no
  forward-ports:
  source-ports:
  icmp-blocks:
  rich rules:
 
# SCP index file
[devops@serverA playbooks]$ cat index.html
<h1>This is Ansible Deployed Website ! </h1>
[devops@serverA playbooks]$ ansible webservers -m ansible.builtin.copy -a 'src=index.html dest=/var/www/html/ '
192.168.208.104 | CHANGED => {
    "ansible_facts": {
        "discovered_interpreter_python": "/usr/bin/python3"
    },
    "changed": true,
    "checksum": "5880f8b97b4dfd17ed95095308b88558010835ef",
    "dest": "/var/www/html/index.html",
    "gid": 0,
    "group": "root",
    "md5sum": "21d306eb3cb6580eee7b103b92971959",
    "mode": "0644",
    "owner": "root",
    "secontext": "system_u:object_r:httpd_sys_content_t:s0",
    "size": 45,
    "src": "/home/devops/.ansible/tmp/ansible-tmp-1729830584.104643-22457-58708790527688/source",
    "state": "file",
    "uid": 0
}
 
# Test in the Original Server ~ For Reference SCP
# Before
[devops@serverD html]$ pwd
/var/www/html
[devops@serverD html]$ ls
[devops@serverD html]$
# After 
[devops@serverD html]$ ls
index.html
[devops@serverD html]$ cat index.html
<h1>This is Ansible Deployed Website ! </h1>

Using Playbook

ansible.cfg  index.html  inventory  webdeploy.yaml
[devops@serverA playbooks]$ cat webdeploy.yaml
- name: Playbook to deploy webpage using apache web server
  hosts: webservers
  tasks:
  - name: Install the latest version of Apache
    ansible.builtin.yum:
      name: httpd
      state: latest
  - name: Start service httpd, if not started
    ansible.builtin.service:
      name: httpd
      state: started
      enabled: yes
  - name: permit http traffic in the firewall
    ansible.posix.firewalld:
      service: http
      permanent: true
      state: enabled
      immediate: yes
  - name: copy index.html file
    ansible.builtin.copy:
      src: index.html
      dest: /var/www/html/index.html
 
# Checking if syntax is correct
[devops@serverA playbooks]$ ansible-playbook --syntax-check webdeploy.yaml
playbook: webdeploy.yaml
 
[devops@serverA playbooks]$ ansible-playbook webdeploy.yaml

Rrmoving

[devops@serverA playbooks]$ cat removewebdeploy.yaml
- name: Playbook to remove deployed web page
  hosts: webservers
  tasks:
  - name: Un-Install the latest version of Apache
    ansible.builtin.yum:
      name: httpd
      state: absent
  - name: Stop service httpd, if not started
    ansible.builtin.service:
      name: httpd
      state: stopped
      enabled: no
  - name: Remove http traffic in the firewall
    ansible.posix.firewalld:
      service: http
      permanent: true
      state: disabled
      immediate: yes
  - name: remove index.html file
    ansible.builtin.file:
      path: /var/www/html/index.html
      state: absent
 
[devops@serverA playbooks]$ ansible-playbook --syntax-check removewebdeploy.yaml
playbook: removewebdeploy.yaml

Creating and Running an Ansible Ad-Hoc Command for Software Installation

As a system administrator, you need to install software on managed hosts using Ansible ad-hoc commands. This task involves creating a shell script (yum-repo.sh) that executes an Ansible ad-hoc command to set up YUM repositories on each managed node. Specifically, you must configure two repositories: BaseOS and AppStream.

[devops@ansible-server ansible]$ cat yum-repos.sh 
ansible all -m yum_repository -a 'file=external_repos name=BaseOS description="BaseOS Repo" baseurl=http://192.168.208.100/softwares/BaseOS gpgcheck=yes gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-centosofficial enabled=yes state=present'
 
ansible all -m yum_repository -a 'file=external_repos name=AppStream description="AppStream Repo" baseurl=http://192.168.208.100/softwares/AppStream gpgcheck=yes gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-centosofficial enabled=yes state=present'
 
[devops@ansible-server ansible]$ chmod +x yum-repos.sh 
[devops@ansible-server ansible]$ ./yum-repos.sh 
[devops@ansible-server ansible]$ ansible all -m command -a 'cat /etc/yum.repos.d/external_repos.repo'
 
node1 | CHANGED | rc=0 >>
[BaseOS]
baseurl = http://192.168.208.100/softwares/BaseOS
enabled = 1
gpgcheck = 1
gpgkey = file:///etc/pki/rpm-gpg/RPM-GPG-KEY-centosofficial
name = BaseOS Repo
 
[AppStream]
baseurl = http://192.168.208.100/softwares/AppStream
enabled = 1
gpgcheck = 1
gpgkey = file:///etc/pki/rpm-gpg/RPM-GPG-KEY-centosofficial
name = AppStream Repo
node3 | CHANGED | rc=0 >>
[BaseOS]
baseurl = http://192.168.208.100/softwares/BaseOS
enabled = 1
gpgcheck = 1
gpgkey = file:///etc/pki/rpm-gpg/RPM-GPG-KEY-centosofficial
name = BaseOS Repo
 
[AppStream]
baseurl = http://192.168.208.100/softwares/AppStream
enabled = 1
gpgcheck = 1
gpgkey = file:///etc/pki/rpm-gpg/RPM-GPG-KEY-centosofficial
name = AppStream Repo
node4 | CHANGED | rc=0 >>
[BaseOS]
baseurl = http://192.168.208.100/softwares/BaseOS
enabled = 1
gpgcheck = 1
gpgkey = file:///etc/pki/rpm-gpg/RPM-GPG-KEY-centosofficial
name = BaseOS Repo
 
[AppStream]
baseurl = http://192.168.208.100/softwares/AppStream
enabled = 1
gpgcheck = 1
gpgkey = file:///etc/pki/rpm-gpg/RPM-GPG-KEY-centosofficial
name = AppStream Repo
node2 | CHANGED | rc=0 >>
[BaseOS]
baseurl = http://192.168.208.100/softwares/BaseOS
enabled = 1
gpgcheck = 1
gpgkey = file:///etc/pki/rpm-gpg/RPM-GPG-KEY-centosofficial
name = BaseOS Repo
 
[AppStream]
baseurl = http://192.168.208.100/softwares/AppStream
enabled = 1
gpgcheck = 1
gpgkey = file:///etc/pki/rpm-gpg/RPM-GPG-KEY-centosofficial
name = AppStream Repo