Hi Martin,

regarding your "no lookup" policy, how do you handle for example deep merge
lookups. They cannot be used with automatic data binding, or am I wrong?

Regards
Karsten

Am Sa., 27. Feb. 2021 um 13:06 Uhr schrieb Martin Alfke <[email protected]>:

> Hi
>
> > On 25. Feb 2021, at 11:59, Dmitry Nurislamov <[email protected]> wrote:
> >
> > Hello. Sometimes it is desirable to define Hiera variables for usage in
> Hiera itself, i.e. variables that won't be looked up from Puppet manifests.
> We do this to avoid repetition. Here's an example of a variable used only
> in the file it is defined:
> >
> >     _internal_api_host: 'int.api.example.com'
> >     profile::keepalived::vrrp_script:
> >       ping_internal_api:
> >         script: "curl https://%{lookup('_internal_api_host')}/ping"
> >     profile::nginx::servers:
> >       "%{alias('_internal_api_host')}":
> >         ...
> >
> > Sometimes we also define this kind of variables in one file but do
> lookups somewhere else:
> >
> > hieradata/project/foo.yaml:
> >     profile::base::network::interfaces:
> >       eth0:
> >         method: 'static'
> >         address: "%{lookup('_INTERNAL_IP')}/24"
> >
> > hieradata/project/foo/foo1.yaml:
> >     _INTERNAL_IP: '10.1.2.3'
> >
> > For us this became an issue. There are no conventions, and therefore no
> consistency in our quite large hiera. Sometimes we can't even tell whether
> some variable is looked up from manifests or is "local" for Hiera. For
> example, the "_INTERNAL_IP" above is named
> "profile::base::network::intern_ip" in some projects.
> >
> > The question is... Is this a normal practice? How do other folks handle
> these cases? I couldn't find any information regarding this. Thanks.
>
> This is part of the way how you can implement hiera.
> We heavily use the same pattern to avoid duplicate data.
> Unluckily there is (yet?) no best practices written down.
>
> Usually we have a pattern that we strictly follow:
> - Never set class parameters on module (technical component or library
> module) level. Only set data on profile classes.
> - Only do automatic data binding, using profile class namespace on hiera
> data, never do explizit lookups in profile classes.
>   - e.g.:profile::base::usermgmt::users: {}
> - nested lookups always use short key names, usually prefixed with company
> or department or team short name
>   - e.g. company_ldap_pass
>
> This pattern allows us to strictly separate data which are needed multiple
> times in hiera.
> Using automatic data binding and the name convention on nested lookups, we
> can easily identify if data is consumed by a class or needed hiera
> internally.
>
> hth,
> Martin
>
>
> >
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