Ansible regex to search and replace an IP Address in a line

Question

I have an Ansible playbook where I need to change the Server Name in one line and an Specific IP address in another line, as in this line there are a bunch of IP address separated by a comma.

I have the below play which works absolutely fine in case I have to change the entire IP address line with the defined set of IP addresses, But I'm looking for specific IP address ie 191.168.1.4 to be looked upon and if found then just replace that only and leave the rest of the IP as it is.

---
- name: Playbook to replace line in zabbix_agentd.conf
  hosts: all
  #remote_user: root
  gather_facts: False

  tasks:
  - name: Changing the zabbix-agent configuration on the client
    lineinfile:
      path: /tmp/zabbix_agentd.conf
      ### line to be searched & matched
      regexp: '{{ item.From }}'
      ### new line to be replaced with the old matched one
      line: '{{ item.To }}'
      state: present
      backup: yes
      backrefs: yes

    with_items:
    - { From: '#ServerActive=myzabbix1.example.com', To: 'ServerActive=myzabbix2.example.com'}
    - { From: 'Server=192.168.1.1,192.168.1.2,192.168.1.3,192.168.1.4,192.168.1.5', To: 'Server=192.168.1.1,192.168.1.2,192.168.1.3,192.168.1.10,192.168.1.5'}
    # Actions will be triggered at the end of each block of task and notifies a handler.
    notify: restart_zabbix_service

  handlers:
  - name: restart_zabbix_service
    # referenced by a globally unique name and are notified by notifiers.
    service:
      name: zabbix-agentd
      state: restarted

Answer 1

Here is a complete MCVE to put you on track. Based on your above content:

---
- name: Replace demo
  hosts: localhost
  gather_facts: false

  vars:
    demo_file_content: |-
      #ServerActive=myzabbix1.example.com
      Server=192.168.1.1,192.168.1.2,192.168.1.3,192.168.1.4,192.168.1.5
      SomeOtherTestForDemo: toto 192.168.1.4 pipo bingo
    demo_file_destination: /tmp/replace_demo.conf

  tasks:
    - name: Start our test from scratch with a fresh file
      copy:
        dest: "{{ demo_file_destination }}"
        content: "{{ demo_file_content }}"

    - name: Check file content before demo
      slurp:
        path: "{{ demo_file_destination }}"
      register: demo_start
    - debug:
        msg: "{{ (demo_start.content | b64decode).split('\n') }}"

    - name: Replace elements in file
      replace:
        path: "{{ demo_file_destination }}"
        regexp: "{{ item.regexp }}"
        replace: "{{ item.replace }}"
      loop:
        # Replace active server and remove comment if exists
        - regexp: "^#?(ServerActive=)myzabbix1.example.com$"
          replace: "\\g<1>myzabbix2.example.com"
        # Replace all occurences of a specific IP anywhere
        - regexp: "^(.*)192\\.168\\.1\\.4(.*)$"
          replace: "\\g<1>192.168.1.10\\g<2>"

    - name: Check file content after demo
      slurp:
        path: "{{ demo_file_destination }}"
      register: demo_end
    - debug:
        msg: "{{ (demo_end.content | b64decode).split('\n') }}"


    - name: Cleanup (unless you pass `-e keep_demo_file=true` to ansible-playbook)
      file:
        path: "{{ demo_file_destination }}"
        state: absent
      when: not keep_demo_file | default(false) | bool

Which gives:

$ ansible-playbook test.yml

PLAY [Replace demo] ***************************************************************************************

TASK [Start our test from scratch with a fresh file] ******************************************************
changed: [localhost]

TASK [Check file content before demo] *********************************************************************
ok: [localhost]

TASK [debug] **********************************************************************************************
ok: [localhost] => {
    "msg": [
        "#ServerActive=myzabbix1.example.com",
        "Server=192.168.1.1,192.168.1.2,192.168.1.3,192.168.1.4,192.168.1.5",
        "SomeOtherTestForDemo: toto 192.168.1.4 pipo bingo"
    ]
}

TASK [Replace elements in file] ***************************************************************************
changed: [localhost] => (item={'regexp': '^#?(ServerActive=)myzabbix1.example.com$', 'replace': '\\g<1>myzabbix2.example.com'})
changed: [localhost] => (item={'regexp': '^(.*)192\\.168\\.1\\.4(.*)$', 'replace': '\\g<1>192.168.1.10\\g<2>'})

TASK [Check file content after demo] **********************************************************************
ok: [localhost]

TASK [debug] **********************************************************************************************
ok: [localhost] => {
    "msg": [
        "ServerActive=myzabbix2.example.com",
        "Server=192.168.1.1,192.168.1.2,192.168.1.3,192.168.1.10,192.168.1.5",
        "SomeOtherTestForDemo: toto 192.168.1.10 pipo bingo"
    ]
}

TASK [Cleanup (unless you pass `-e keep_demo_file=true` to ansible-playbook)] *****************************
changed: [localhost]

PLAY RECAP ************************************************************************************************
localhost                  : ok=7    changed=3    unreachable=0    failed=0    skipped=0    rescued=0    ignored=0