[openstack-dev] [puppet] Parameters possible default value

Yanis Guenane yguenane at redhat.com
Fri Jul 17 08:56:10 UTC 2015

Hello everyone,

Based on the conversation we had during last meeting I went ahead and
created an  
ini_setting provider[1] that will act as a proxy between our provider
and the
upstream one, this way we don't have to fork, only overload the method
we want.

The second step towards parameter default management was to provide a
way that
means if 'X' is specified as the value for the provider then ensure it
is absent.

This way we could move from the following pattern :

  if $myvar {
    keystone_config {'DEFAULT/foo': value => $myvar,
  } else {
    keystone_config {'DEFAULT/foo': ensure => absent,

to a more readable one that would have been

  keystone_config {'DEFAULT/foo': value => $myvar, }

that based on the value of $myvar would have ensure absent the parameter.

In a first time the empty string seemed to have been a good idea, so we
have default all the parameters to '' (empty string) and live happily
ever after,
if set the value would have been set else it would default to upstream

But Mathieu raised a fair point here[2] is that an empty string for some
settings is a valid value, and hence we can't rely on

Since the beginning we are trying to avoid the use of a magic string, but
I am starting to run out of idea here.

Does someone has an idea on which sane value the default could be ?

Thanks in advance,

[1] https://review.openstack.org/#/c/202488
[2] https://review.openstack.org/#/c/202574
Yanis Guenane

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