To Henrik: Yes, this make sense, it would be nice to have some easy way to
keep the purely Puppet DSL portions separate though.
Walter: This would be nice, but variables are the...uh...variable here.
Many people only expose the variables that they need while others expose
every variable they can find. It would be an interesting experiment to see
if it would work though.
Trevor
On Tue, Feb 10, 2015 at 1:52 PM, Walter Heck <walterh...@olindata.com>
wrote:
> I'm personally more of a fan of what some programming languages call
> interfaces; a sort of contract if you will that a module implements.
>
> So for instance olindata::galera could look for any class that implements
> the IMysql interface. That way, I don't really need to worry if the
> end-user is using puppetlabs::mysql or example42::mysql, as long as they
> implement the IMysql interface I can guarantee it does what I need.
>
> This would have pretty heavy impact on how you write code right now, but
> it would be a rather elegant solution imho.
>
> interface IMysql::server identified by
> '9ff3d80b-b02d-4994-b4da-e1ff205304ea' {
> Service['mysql']
> Package['mysql-server']
> File['apache2.conf']
> }
>
> class puppetlabs::mysql implements
> IMysql['9ff3d80b-b02d-4994-b4da-e1ff205304ea'] {
> [.. SNIP..]
> # file, service, package here like normal
> }
>
> class example42::mysql implements
> IMysql['9ff3d80b-b02d-4994-b4da-e1ff205304ea'] {
> [.. SNIP..]
> # file, service, package here like normal
> }
>
> class olindata::galera {
> package { 'galera':
> require => Package['IMysql::server::mysql-server']
> }
> }
>
> Or something along those lines. Question remains where the IMysql::server
> interface then needs to be declared, and how we would manage the GUID
> registration of interfaces.
>
> Comments, thoughts?
>
> Walter
>
>
> On Tuesday, February 10, 2015 at 5:52:37 PM UTC+1, henrik lindberg wrote:
>
>> On 2015-10-02 1:23, Trevor Vaughan wrote:
>> > I was talking with a few folks today about potential resolutions to
>> > module namespace issues.
>> >
>> > == Fundamental Issue ==
>> >
>> > puppetlabs_apache -- Installs To --> apache
>> > example42_apache -- Installs To --> apache
>> > theforeman_apache -- Installs To --> apache
>> >
>> > You get my point...
>> >
>> > == Current Solutions ==
>> >
>> > Right now, there are two ways to solve this problem if you want some of
>> > your nodes to use puppetlabs_apache and others to use
>> theforeman_apache.
>> >
>> > 1) Modify the module and force the namespace:
>> > - puppetlabs_apache -- Installs To --> puppetlabs_apache
>> > - theforeman_apache -- Installs To --> theforeman_apache
>> >
>> > * Isssue: You can't just use outside code at will. You have to
>> modify
>> > *everything* that uses the above code.
>> >
>> > 2) You have to create a separate environment for each host group
>> > (potentially each host) that you want to have use the differing code.
>> >
>> > * Issue: This is a LOT of overhead for a couple of modules and may
>> > have other ramifications in terms of performance as you get up in
>> number.
>> >
>> > So, would it be possible to allow multiple versions of a module to
>> exist
>> > in the same namespace but only use one during a given run?
>> >
>>
>> Basically no, this is not possible without adding some kind of mechanism
>> to filter out modules on the modulepath. This will need to be done per
>> environment anyway. Remember that modules can contribute all sorts of
>> extensions to puppet (faces, indirections, facts, functions, types, and
>> with future parser also bindings). For performance reasons (and
>> bootstrapping, etc.) these are scanned when the environment loads (some
>> scans are lazy, but may take place before manifests really starts to be
>> evaluated).
>>
>> - henrik
>>
>> > == The First Proposal ==
>> >
>> > Inspired by RVM Gemsets, how about allowing modules to declare which
>> > version of a given module they will use?
>> >
>> > /etc/puppet/modules/apache/puppetlabs/{files,modules,manifests}
>> > /etc/puppet/modules/apache/theforeman/{files,modules,manifests}
>> > /etc/puppet/modules/apache/<author>/{files,modules,manifests}
>> >
>> > Then, use could be dictated by something like: include
>> apache@puppetlabs.
>> >
>> > Unfortunately, this really comes down to the parser being able to
>> > understand the following:
>> >
>> > include apache => See if there are any @'s and use that one
>> > include apache@puppetlabs => include the Puppetlabs apache
>> > include apache@puppetlabs && include apache@theforeman => Fail,
>> conflict
>> >
>> > == Alternative ==
>> >
>> > One possible alternative is to just use the metadata.json file to
>> > dictate which module will be used when loading other modules.
>> >
>> > Again, if there is a conflict, that is a failure but *only* if the code
>> > attempts to use both at the same time.
>> >
>> > The benefit here is that it should make things very unambiguous while
>> > the drawback (if it really is) is that you *must* put a metadata.json
>> > file in every module that you create.
>> >
>> > This is just a set of thoughts that I hope get us moving in a direction
>> > where this type of thing is possible and I look forward to hearing what
>> > people think (good, bad, or ugly)!
>> >
>> > Thanks,
>> >
>> > Trevor
>> >
>> > --
>> > Trevor Vaughan
>> > Vice President, Onyx Point, Inc
>> > (410) 541-6699
>> > tvau...@onyxpoint.com <mailto:tvau...@onyxpoint.com>
>> >
>> > -- This account not approved for unencrypted proprietary information --
>> >
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>> 3DinW9obDpwii7gBi6W4RkHycViibJp-g%40mail.gmail.com
>> > <https://groups.google.com/d/msgid/puppet-dev/CANs%2BFoU2unExPve9ig%
>> 3DinW9obDpwii7gBi6W4RkHycViibJp-g%40mail.gmail.com?utm_
>> medium=email&utm_source=footer>.
>> > For more options, visit https://groups.google.com/d/optout.
>>
>>
>> --
>>
>> Visit my Blog "Puppet on the Edge"
>> http://puppet-on-the-edge.blogspot.se/
>>
>> --
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--
Trevor Vaughan
Vice President, Onyx Point, Inc
(410) 541-6699
tvaug...@onyxpoint.com
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