正则表达式ansible lineinfile子节

Question

I am fairly new to ansible and have been solving the following problem with a shell script, but the proper way I believe is to use the lineinfile module, just not sure how to accomplish this.

Let's say I have a file with the following text in it.

<cpu>
   <alarm>
      active = yes
   </alarm>
</cpu>
<disk>
   <alarm>
      active = yes
      <fixed>
         <#>  
            active = yes
            description = File system /
            <inode_error>
               active = yes
               threshold = 2
               message = InodeError
            </inode_error>
         </#>
         <#boot>
            active = yes
            description = File system /boot
            percent = yes
            <error>
               active = yes
               threshold = 5
               message = DiskError
            </error>
         </#boot>
      </fixed>
   </alarm>
</disk>

I want to make sure the following section is set correctly.

<disk><alarm><fixed><#boot><error>"threshold = 2"</error></#boot></fixed></alarm></disk>

is there a way to only (modify/make sure exists) that line, normally this file is much larger with many more sections, but I erased some so the question is readable.

Update: Modifying this as it is not valid XML and the XML module will not parse the file correctly.

Thanks!

Answer 1

lineinfile scans file per line, so you can't define complex multiline regexp for context definition.

replace module support multiline regexp.

If you have threshold = X in the file and want to be sure it is set to specific value, you can use this regexp:

- replace:
    path: ./test.txt
    regexp: '(<disk>[\s\S]*<alarm>[\s\S]*<#boot>[\s\S]*<error>[\s\S]*)(threshold\s*=\s*\d+)([\s\S]*?<\/error>)'
    replace: '\1threshold = 2\3'

It searches for line threshold\\s*=\\s*\\d+ inside <disk>...<alarm>...<#boot>...<error>... . This code is idempotent – so if threshold = 2 , then nothing is done.

But if there is no threshold = X string, it will fail. You should construct more complex regular expression for that case.

Answer 2

you could use the lineinfile module ( http://docs.ansible.com/ansible/latest/lineinfile_module.html ) where you could write a regex to modify/add the line and use the validate function to run a command to ensure that the xml file has the proper syntax.

If you are on Ansible 2.4 you can use the xml module ( https://docs.ansible.com/ansible/2.4/xml_module.html ) and use the attribute parameter to check if the xpath in xml file is set, like that:

- name: Read attribute value
  xml:
    path: /foo/bar.xml
    xpath: /business/website/validxhtml
    content: attribute
    attribute: validatedon
  register: xmlresp

regards