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Ansible part 2: how to use modules - debug copy file template ping gather-facts user group

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Ansible configuration

Before running ansible,I am going to write a default inventory which will be used when I am running site.yml.

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[defaults]
inventory = hosts

Ansible commands

Instead of using ansible playbook, I can also use ansible command to run automation, for example, I am going to check remote nodes directories, I can use ansible command to do that directly, no need to login romote node to check.

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anna@ansible-controller:~/Desktop/ansible-code/inventory/modules/files-modules/inventory$ ansible all -m shell -a "ls /etc/tmp"
ansible-node1 | SUCCESS | rc=0 >>
ansible-file-test.txt
ansible-file-test.txt.16075.2020-05-24@22:58:43~

cube4200 | SUCCESS | rc=0 >>
ansible-file-test.txt
ansible-file-test.txt.11629.2020-05-24@15:58:44~

The command I used is ansible all -m shell -a "ls /etc/tmp"

some examples of how to use modules

Utilities modules -> debug -> print statements during execution

In this module, only three parameters.

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- name: hello world
  hosts: localhost
  tasks:
   - name: hello world
     debug:
      msg: "hello ansible"
      verbosity: 0     # 0 is default, 1-3 parameters will skip the message

running it

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anna@ansible-controller:~/ansible-code/inventory$ ansible-playbook helloworld.yml 
 [WARNING]:  * Failed to parse /etc/ansible/hosts with yaml plugin: YAML inventory has invalid structure, it should be
a dictionary, got: <class 'ansible.parsing.yaml.objects.AnsibleUnicode'>

 [WARNING]:  * Failed to parse /etc/ansible/hosts with ini plugin: /etc/ansible/hosts:44: Expected key=value host
variable assignment, got: ansible-controller

 [WARNING]: Unable to parse /etc/ansible/hosts as an inventory source

 [WARNING]: No inventory was parsed, only implicit localhost is available

 [WARNING]: provided hosts list is empty, only localhost is available. Note that the implicit localhost does not match
'all'


PLAY [hello world] *****************************************************************************************************

TASK [Gathering Facts] *************************************************************************************************
ok: [localhost]

TASK [hello world] *****************************************************************************************************
ok: [localhost] => {
    "msg": "hello ansible"
}

PLAY RECAP *************************************************************************************************************
localhost                  : ok=2    changed=0    unreachable=0    failed=0
files modules: copy and file

I am going to create a directory and copy some files to remote nodes, so I am going to use two modules, copy and file which will create directory.

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- name: file module
  hosts: all
  gather_facts: no
  become: yes     # sudo to root

  tasks:
    - name: mkdir
      file:
        path: /etc/tmp/   # etc dir needs root right
        state: directory

    - name: copy files from local to remote
      copy:
          src: files/ansible-file-test.txt
          dest: /etc/tmp/ansible-file-test.txt
          backup: yes   # will keep the same name file not be overwrite,give file a time tag

after running

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anna@ansible-controller:~/Desktop/ansible-code/inventory/modules/files-modules/invento$ ansible-playbook site.yml

PLAY [file module] *******************************************************************

TASK [mkdir] *************************************************************************
ok: [ansible-node1]
ok: [cube4200]

TASK [copy files from local to remote] ***********************************************
changed: [ansible-node1]
changed: [cube4200]

PLAY RECAP ***************************************************************************
ansible-node1              : ok=2    changed=1    unreachable=0    failed=0   
cube4200                   : ok=2    changed=1    unreachable=0    failed=0

file modules create a dir named tmp under /etc, since I sudo to root, so I can create dir under etc. after dir is created, I copied my local file named ansible-file-test.txt to node’ destination dir.

template modules: template

template is like a different copy, in which data is got by variables.
Usaually template file is wrote by jinja, so the end of file is .j2.
following is a template file named template-demo.j2

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[default]
ansible_user = {{ ansible_user }}
[demo]
{% for ip in range(201, 220) %}
{{ host_prefix }}{{ "%02d" | format(id-200)}}-{{ ip_prefix}}.{{ ip }}
{% endfor %}

this is template playbook

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- name: template test
      template:
          src: templates/template-demo.j2
          dest: /etc/tmp/test.cfg
system module: ping

There are two ways to ping hosts, first use command line
ansible -m ping all -i inventory

second ways is to use playbook

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tasks:
    - name: test ping moudle
      ping:

both work as following:

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anna@ansible-controller:~/Desktop/ansible-code/inventory/modules/system_modules/inventory$ ansible-playbook site.yml 

PLAY [system module] ************************************************************

TASK [test ping moudle] *********************************************************
ok: [cube4200]
ok: [ansible-node1]

PLAY RECAP **********************************************************************
ansible-node1              : ok=1    changed=0    unreachable=0    failed=0   
cube4200                   : ok=1    changed=0    unreachable=0    failed=0
system module: gather_facts

In command line, use ansible -m gather_facts -i inventory --tree ./facts, which will get all info of nodes and save it to file which is named facts. If I need the info from facts I can just call it in playbook. For example, I am going to print out the nodes’s distribution.

Notice: the default of gather_facts is yes, which means, it will get all info if you did not specify it is No.

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tasks:
    - name: print facts
      debug:
        msg: "{{ ansible_distribution }}"

after running

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TASK [print facts] **************************************************************
ok: [cube4200] => {
    "msg": "CentOS"
}
ok: [ansible-node1] => {
    "msg": "Debian"
}
system module: user and group

manage user and group in linux, such as add new user and group or delete them.

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tasks:
    - name: create group
      group:
        name: ansible_demo
        state: absent  # this is default state
    - name: create user
      user:
        name: demo
    - name: delete user
      user:
        name: demo
        state: absent   # will not delete home dir
        remove: yes    # add this command will delete  user home dir

to be continued