Note about commenting out j2 configs

[Stephen Smoogen]

I have done this myself a couple of times myself so wanted to be clear that
when you comment out regions in j2 it doesn't act like you would expect.
Basically, j2 decisions end of lines are 'eaten' and the next line is
appended to your previous one. This works great in many places but can kill
you in others.

A change like this:
```
# Comment out emails until we fix deeper issue
#{% if env == 'production' %}
#'mail_admins',
#{% endif %}
],
```
will end up with this:
```
# Comment out emails until we fix deeper issue
#                #'mail_admins',
#                ],
```
versus what is expected. If you are commenting out some j2 decision code,
always add either a blank line after words OR an addition comment line at
the end
```
# Comment out emails until we fix deeper issues
#{% if env == 'production' %}
#'mail_admins',
#{% endif %}
#
```
will go to
```
# Comment out emails until we fix deeper issues
#                #'mail_admins',
#                #
```

The most likely place you will run into this is the giant mess of nagios
configs I left for infrastructure. There are many times where you may need
to comment out a decision to see if it's the place nagios is currently
puking itself.. and you end up with now two places nagios is puking itself.
-- 
Stephen Smoogen, Red Hat Automotive
Let us be kind to one another, for most of us are fighting a hard battle.
-- Ian MacClaren

[Lpuvilla0001]

 Thank you for the tip! Learned something new today.
 

 
+1
 
 
 
 
 
 
 

 
 
>   
>  On Feb 22, 2022 at 6:32 AM,  <Stephen Smoogen (mailto:[e-mail])> 
> wrote:
>   
>   
>   
>
>   
>  I have done this myself a couple of times myself so wanted to be clear that when you
> comment out regions in j2 it doesn't act like you would expect. Basically, j2
> decisions end of lines are 'eaten' and the next line is appended to your previous
> one. This works great in many places but can kill you in others.
>   
>   A change like this:
>   ```
>   # Comment out emails until we fix deeper issue
>   #{% if env == 'production' %}
>   #'mail_admins',
>   #{% endif %}
>   ],
>   ```
>   will end up with this:
>   ```
>   # Comment out emails until we fix deeper issue
>   #                                #'mail_admins',
>   #                                ],
>   ```
>   versus what is expected. If you are commenting out some j2 decision code, always add
> either a blank line after words OR an addition comment line at the end
>   ```
>   # Comment out emails until we fix deeper issues
>   #{% if env == 'production' %}
>   #'mail_admins',
>   #{% endif %}
>   #
>   ```
>   will go to
>   ```
>   # Comment out emails until we fix deeper issues
>   #                                #'mail_admins',
>   #                                #
>   ```
>   
>   The most likely place you will run into this is the giant mess of nagios configs I left
> for infrastructure. There are many times where you may need to comment out a decision to
> see if it's the place nagios is currently puking itself.. and you end up with now two
> places nagios is puking itself.  
>   --
>   
>   
>   
>   
>
>   Stephen Smoogen, Red Hat Automotive
>   Let us be kind to one another, for most of us are fighting a hard battle. -- Ian
> MacClaren
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>

[David Sastre]

Note that jinja2 syntax allows for proper comments[1] as well.
So if you were to comment out a line or a block for any reason, you could
also use:

```
{# Comment out emails until we fix deeper issue
#{% if env == 'production' %}
#'mail_admins',
#{% endif %}
#}
],
```

Depends, obviously on whether you want the comment to be in the code only,
or rendered out in the target file.

[1]: https://jinja.palletsprojects.com/en/3.0.x/templates/#comments

On Tue, Feb 22, 2022 at 4:11 PM Lpuvilla0001 <lpuvilla0001(a)mymail.lausd.net&gt;
wrote:

>  Thank you for the tip! Learned something new today.
>
>  +1
>
>
>
>  On Feb 22, 2022 at 6:32 AM, <Stephen Smoogen> wrote:
>
>
>  I have done this myself a couple of times myself so wanted to be clear
>  that when you comment out regions in j2 it doesn't act like you would
>  expect. Basically, j2 decisions end of lines are 'eaten' and the next line
>  is appended to your previous one. This works great in many places but can
>  kill you in others.
>
>  A change like this:
>  ```
>  # Comment out emails until we fix deeper issue
>  #{% if env == 'production' %}
>  #'mail_admins',
>  #{% endif %}
>  ],
>  ```
>  will end up with this:
>  ```
>  # Comment out emails until we fix deeper issue
>  #                #'mail_admins',
>  #                ],
>  ```
>  versus what is expected. If you are commenting out some j2 decision code,
>  always add either a blank line after words OR an addition comment line at
>  the end
>  ```
>  # Comment out emails until we fix deeper issues
>  #{% if env == 'production' %}
>  #'mail_admins',
>  #{% endif %}
>  #
>  ```
>  will go to
>  ```
>  # Comment out emails until we fix deeper issues
>  #                #'mail_admins',
>  #                #
>  ```
>
>  The most likely place you will run into this is the giant mess of nagios
>  configs I left for infrastructure. There are many times where you may need
>  to comment out a decision to see if it's the place nagios is currently
>  puking itself.. and you end up with now two places nagios is puking itself.
>  --
>  Stephen Smoogen, Red Hat Automotive
>  Let us be kind to one another, for most of us are fighting a hard battle.
>  -- Ian MacClaren
>  _______________________________________________ infrastructure mailing
>  list -- infrastructure(a)lists.fedoraproject.org To unsubscribe send an
>  email to infrastructure-leave(a)lists.fedoraproject.org Fedora Code of
>  Conduct: https://docs.fedoraproject.org/en-US/project/code-of-conduct/
>  List Guidelines: https://fedoraproject.org/wiki/Mailing_list_guidelines
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>  https://lists.fedoraproject.org/archives/list/[e-mail]...
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>
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