Extracting part of the string using Ansible regex_search and save the output as a variable

Question

I'm having a content like below inside a file.

dataDir=/var/lib/zookeeper
4lw.commands.whitelist=mntr,conf,ruok,stat
syncLimit=2

I wanted to read the value for dataDir using Ansible and set it to a variable. I have written following code but regular expression and storing the variable both have some issues.

  - name: Read zoo.cfg content
    shell:
      cmd: cat zoo.cfg
    register: zoo_config_content

  - set_fact:
      my_var: "{{ zoo_config_content.stdout | regex_search('dataDir.*')}}"

  - name: Print
    debug:
      var: my_var

Q1.) How can I improve the regular expression to get only /var/lib/zookeeper ?

Q2.) How can I store that extracted value to use in another task?

Solution

You need to add a group to your regex and a second parameter that specifies which group to return:

- set_fact:
    my_var: "{{ zoo_config_content.stdout | regex_search('dataDir=(.+)', '\\1') | first }}"

This would return an array with a single element, so I added | first to get only one element directly as a string.

Result:

ok: [localhost] => {
    "my_var": "/var/lib/zookeeper"
}

If the config file resides on the Ansible machine you can make it even easier using a lookup:

- set_fact:
    my_var: "{{ lookup('file', 'zoo.cfg') | regex_search('dataDir=(.+)', '\\1') | first }}"

Comments

[Admin]

Please don't ask multiple questions in one question, add a separate question for your second part. But with set_fact you already stored the value and can use it. If you open an additional question please elaborate more what's your problem with that variable.

[AnujAroshA]

Thanks set_fact works with the regular expression. But lookup will not work on the remote machine. Will it? The other thing that's issue with lookup is, the same code lookup('url',... runs in Linux machine but not in macOS.

[dortegaoh]

You are right, lookup works locally, my fault.

[divay singhal]

- set_fact: my_var: "{{ zoo_config_content.stdout | regex_search('dataDir=(.+)', '\\1') | first }}" what if the value is not avaiable will it give below result my_var: ""

[dortegaoh]

You should ask this as a question. You can link here as a reference.