Center text in j2 template

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1

I’m trying to work up a template for a text file and can’t figure out how to get a string centered in a set number of columns.

One thing I’m trying to do is write a new /etc/motd file that will have as part of it a line with 3 ‘*’ characters at the beginning and end of the line that is 60 characters long, with ansible_fact[hostname] centered on the line. The hostnames are all different lengths so I need to rely on some sort of formatting string to center the text. Basically like this:

*****************************
***     <insert text>     ***
*****************************

I can get the desired format in python but haven’t figured out how to embed that in the playbook to be included in the resulting file. I think the best way would be to figure out the proper syntax in a j2 template but haven’t had much luck there either.

This hostname line in motd is just one instance of a longer list of templates I need to write, but it’s a good representation of the overall need.

2

I’d suggest using awk or another tool for this, if it has to be done using Jinja2 I guess you would need to count the number of characters per line, deduct that from the line length and half it to work out what padding is required.

3

Jinja has an awesome center filter :smiley: : Template Designer Documentation — Jinja Documentation (3.1.x)

- hosts: localhost
  gather_facts: false
  vars:
    motd_banner: |
      {{ '*' * motd_width }}
      {{ '*' * motd_border_width }}{{ motd_centered }}{{ '*' * motd_border_width }}
      {{ '*' * motd_width }}
    motd_centered: "{{ motd | center(motd_width - (motd_border_width * 2)) }}"
    motd_border_width: 3
    motd_width: 60

  tasks:
    - ansible.builtin.debug:
        var: motd_banner
      vars:
        motd: "This is the message of the day!"

    - ansible.builtin.debug:
        var: motd_banner
      vars:
        motd: "If the number of characters is even (40)"

    - ansible.builtin.debug:
        var: motd_banner
      vars:
        motd: "If the number of characters is odd (39)"

PLAY [localhost] *************************************************************************************************

TASK [ansible.builtin.debug] *************************************************************************************
ok: [localhost] => 
    motd_banner: |-
        ************************************************************
        ***           This is the message of the day!            ***
        ************************************************************

TASK [ansible.builtin.debug] *************************************************************************************
ok: [localhost] => 
    motd_banner: |-
        ************************************************************
        ***       If the number of characters is even (40)       ***
        ************************************************************

TASK [ansible.builtin.debug] *************************************************************************************
ok: [localhost] => 
    motd_banner: |-
        ************************************************************
        ***       If the number of characters is odd (39)        ***
        ************************************************************

PLAY RECAP *******************************************************************************************************
localhost                  : ok=3    changed=0    unreachable=0    failed=0    skipped=0    rescued=0    ignored=0
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4

Found the syntax after a bunch of trial and error just now:

********************************************************************
*****                                                          *****
*****{{ "{:^58}".format(ansible_facts.hostname) }}*****
*****                                                          *****
********************************************************************
*****{{ "{:^58}".format('%Y%m%d / %H%ML' | strftime(ansible_date_time.epoch)) }}*****
********************************************************************

Results in:

********************************************************************
*****                                                          *****
*****                         thishost                         *****  
*****                                                          *****
********************************************************************
*****                     20240526 / 0908L                     *****
********************************************************************

I’ve got other info in the actual motd but this gives a good idea of how to format it and what it ends up looking like.

3 Likes