Initialize hosts formula

[tacerus]

No description provided.

[cboltz]

I have some generic questions about this PR:

• do you really need a formula for /etc/hosts? (In other words: what's the problem with host.present and host.absent?)
• what's the reason for introducing hosts AND infrastructure.hosts? I'd say one of them is enough ;-) - and if you really need two variants, I'd prefer an if over duplicated code.

[tacerus]

Hi @cboltz,

this is indeed a replacement for the hostsfile formula (that is currently used in the openSUSE infrastructure for the purpose of managing /etc/hosts), which, through the use of the host state functions cannot enforce a certain state of /etc/hosts - in other words, there is no clean option to make an entry get removed if it is removed from host.present without also adding it to host.absent.

The infrastructure.hosts state is mainly used to enable the opinionated template adding hosts entries based on data found in our infrastructure and network pillars, using logic which is specific to our infrastructure (for example, it assumes addresses to start with a certain number and interfaces to end with a certain suffix). So far we do not have any opinionated (= specific to our infrastructures) code outside of the infrastructure-formula, and I would prefer not to introduce any.

[tacerus]

To implement the cleanup logic with the host state functions, one would need to add logic which reads and parses the /etc/hosts file to assess whether entries are still to be managed.

[cboltz]

Ok, the missing clean parameter is indeed a good argument to have a hosts formula.

I'm still not convinced that we need hosts and infrastructure.hosts, even if I understand your reasons. For the opinionated part - would making the template file configurable via pillar (and shipping the opinionated version in infrastructure´) be an option so that we don't need to duplicate init.sls, and (more important) don't need the note that hostsandinfrastructure.hosts` conflict?