Replace a line in a config file with ansible

问题:

I am new to ansible.

Is there a simple way to replace the line starting with option domain-name-servers in /etc/dhcp/interface-br0.conf with more IPs?

  option domain-name-servers 10.116.184.1,10.116.144.1;

I want to add ,10.116.136.1

回答1:

You can use the lineinfile Ansible module to achieve that.

  - name: replace line
    lineinfile: 
      dest: /etc/dhcp/interface-br0.conf 
      regexp: '^(.*)option domain-name-servers(.*)$' 
      line: 'option domain-name-servers 10.116.184.1,10.116.144.1,10.116.136.1;'
      backrefs: yes

The regexp option tells the module what will be the content to replace.

The line option replaces the previously found content with the new content of your choice.

回答2:

You can use Replace Module. Please refer to http://docs.ansible.com/ansible/latest/modules/replace_module.html.

#example
vim httpd-replace-hostname.yml

---
- hosts: <Your ansible host>
  tasks:
  - name: hostname was used instead of path.
    replace:
      path: /etc/hosts
      regexp: '(\s+)old\.name\.com(\s+.*)?$'
      replace: '\new.name.com\2'
      backup: yes

Run

ansible-playbook httpd-replace-hostname.yml

You can check out the result successfully as below.

PLAY [Your hosts] ***************************************************************************************************************************************************************

TASK [Gathering Facts] **********************************************************************************************************************************************************
ok: [hostname.name.com]

TASK [hostname was used instead of path.] ***************************************************************************************************************************************
ok: [hostname.name.com]

TASK [Replace after the expression till the end of the file] ********************************************************************************************************************
changed: [hostname.name.com]

PLAY RECAP **********************************************************************************************************************************************************************
hostname.name.com : ok=3    changed=1    unreachable=0    failed=0 

回答3:

I created a role dhcp with the following main.yaml:

---
- name: add all dns servers
  lineinfile:
    dest: /etc/dhcp/interface-br0.conf
    regexp: '^\s*option domain-name-servers.*$'
    line: '  option domain-name-servers 10.116.184.1,10.116.144.1,10.116.136.1;'
    backrefs: yes
  become: true

回答4:

we can use lineinfile module to replace a line

using ad-hoc command:

ansible <host> -m lineinfile -a "path=/etc/dhcp/interface-br0.conf regexp=''^(.*)option domain-name-servers(.*)$'' line='1option domain-name-servers 10.116.184.1,10.116.144.1,10.116.136.1;' backrefs: yes"

using ansible playbook:

- name: replacing a line in file
  lineinfile: 
    path: /etc/dhcp/interface-br0.conf 
    regexp: '^(.*)option domain-name-servers(.*)$' 
    line: 'option domain-name-servers 10.116.184.1,10.116.144.1,10.116.136.1;'
    backrefs: yes

for more we can check for other options: in lineinfile module

https://docs.ansible.com/ansible/latest/modules/lineinfile_module.html