We have already run few ad-hoc command to list down the hosts in earlier sections.
See all parts of Automation with Ansible Guides here
ansible <hosts | all> -m <module> -a <arguments>
Let’s try few modules to run as ad-hoc commands. Below one is a sample command to execute ping module on those listed hosts.
[root@ansible-box ~]# ansible all -m ping -i mylist
box2 | SUCCESS => {
"changed": false,
"ping": "pong"
}
box1 | SUCCESS => {
"changed": false,
"ping": "pong"
}
Another one to check host uptime and user id using command module.
[root@ansible-box ~]# ansible all -i mylist -m command -a "uptime"
box2 | SUCCESS | rc=0 >>
07:15:49 up 1:12, 2 users, load average: 0.00, 0.00, 0.00
box1 | SUCCESS | rc=0 >>
07:15:49 up 15 min, 2 users, load average: 0.00, 0.00, 0.00
[root@ansible-box ~]# ansible all -i mylist -m command -a "id"
box2 | SUCCESS | rc=0 >>
uid=0(root) gid=0(root) groups=0(root)
box1 | SUCCESS | rc=0 >>
uid=0(root) gid=0(root) groups=0(root)
Some more examples below.
Install/Remove Package
[root@ansible-box ~]# ansible webservers -i mylist -m yum -a "name=httpd state=present"
#Or
[root@ansible-box ~]# ansible webservers -i mylist -m yum -a "name=httpd state=absent"
Install on Ubuntu using module apt
[root@ansible-box ~]# ansible -i mylist webservers -m apt -a "name=apache2 state=present"
Start and enable a service
[root@ansible-box ~]# ansible -i mylist dbservers -m service -a "name=httpd state=started enabled=yes"
As we discussed earlier, we must use -b to become privileged user to install items. Let’s say we are using devops user to login (remote_user), make sure devops has sudo access on the target machine.
[devops@node1 ~]$ sudo cat /etc/sudoers.d/devops
[sudo] password for devops:
devops ALL=(ALL) NOPASSWD: ALL
Let’s try one command module without switching as privileged user.
[devops@ansible-box dep-adhoc]$ ansible localhost -m command -a 'id'
localhost | SUCCESS | rc=0 >>
uid=1000(devops) gid=1000(devops) groups=1000(devops),10(wheel) context=unconfined_u:unconfined_r:unconfined_t:s0-s0:c0.c1023
You can see, the output shows devops user details.
Now we will try command module with switching to dbadmin user and see the different.
[devops@ansible-box dep-adhoc]$ ansible localhost -m command -a 'id' -u dbadmin
localhost | SUCCESS | rc=0 >>
uid=1002(dbadmin) gid=1002(dbadmin) groups=1002(dbadmin) context=unconfined_u:unconfined_r:unconfined_t:s0-s0:c0.c1023
Let’s try another command with copy module as using privileged user.
[devops@ansible-box dep-adhoc]$ ansible localhost -m copy -a 'content="Managed by Ansible\n" dest=/etc/motd' -u devops --become
localhost | SUCCESS => {
"changed": true,
"checksum": "4458b979ede3c332f8f2128385df4ba305e58c27",
"dest": "/etc/motd",
"gid": 0,
"group": "root",
"md5sum": "65a4290ee5559756ad04e558b0e0c4e3",
"mode": "0644",
"owner": "root",
"secontext": "system_u:object_r:etc_t:s0",
"size": 19,
"src": "/home/devops/.ansible/tmp/ansible-tmp-1523860264.94-170788199948146/source",
"state": "file",
"uid": 0
}
Another example using file module.
$ ansible webservers -m file -a "dest=/tmp/mytext.txt mode=600"
# or
$ ansible dbservers -m file -a "dest=/tmp/mytext.txt mode=755 owner=devops group=devops"
And, please note some of the important arguments or option you can use while running ansible ad-hoc commands.
-m MODULE_NAME, --module-name=MODULE_NAME # module name to execute (default=command)
-a MODULE_ARGS, --args=MODULE_ARGS # module arguments
-i INVENTORY, --inventory=INVENTORY # specify inventory host path or comma separated host list.
--list-hosts # outputs a list of matching hosts; does not execute
anything else
-b, --become # run operations with become
--become-method=BECOME_METHOD # privilege escalation method to use (default=sudo
--become-user=BECOME_USER # run operations as this user
We will explain about playbooks in next session.
See all parts of Automation with Ansible Guides here
Gineesh Madapparambath
Gineesh Madapparambath is the founder of techbeatly. He is the co-author of The Kubernetes Bible, Second Edition and the author of Ansible for Real Life Automation. He has worked as a Systems Engineer, Automation Specialist, and content author. His primary focus is on Ansible Automation, Containerisation (OpenShift & Kubernetes), and Infrastructure as Code (Terraform). (Read more: iamgini.com)
