A while back I wrote down all the puppet patterns
I could think of, and this was one of them.
I named it Cradle To Grave, but probably that's not
appropriate. However, I was only focusing on
puppet runs at the time, so that name popped into my head.
It is an instance of the more general pattern Convention
Over Configuration.
Of course, sites will define their own stage sequences.
But there is still benefit to having a canonical sequence
to refer to when publishing modules.
I think the trick to making it work generally
is to allow renaming of the stages.
That is, the stages are referred to through
variables, so the stage names can be
changed by, for example, sub-classing
in order to make them fit into a site design.
I've got one module that uses stages.
I think I will change it to make the stage names
an abstraction and see how that works.
-vagn
CRADLE TO GRAVE
problem:
There are many steps that must be done in sequence.
Expressing that through dependencies is tedious,
and violates the principle of encapsulation (or something).
solution:
Convention over configuration:
have some canonical stages.
also have module specific stages
that relate to the canonical stages.
canonical stages (but, don't take this particular list seriously):
local-pre
local
local-post
network-pre
network
network-post
.. as above, there is a -pre and -post version of
provisioning
package
package-update
lib
comms
mounts
scripts
services
db
web
bikeshed
main
app
ha
env
restart
module stages:
foo-local-pre
foo-network
foo-mounts-post
foo-whatever
pros:
don't have to constantly mess with dependencies,
just slot the module in where it belongs in the
grand scheme.
cons:
deciding where to put the bikeshed
On 06/09/2011 09:50 PM, Jacob Helwig wrote:
On Thu, 09 Jun 2011 18:42:54 -0700, Nigel Kersten wrote:
https://projects.puppetlabs.com/issues/7697
One problem people producing modules that make use of stages are hitting is
that it's difficult to create something reusable that integrates seamlessly
into existing setups.
This feature request is to add several more implicit stages to Puppet so we
have:
bootstrap
pre
main
post
existing by default, making it easier for authors to specify stages in their
modules.
Thoughts?
The answer to question "Which comes first, 'bootstrap' or 'pre'?" seems
awfully ambiguous from just the names.
What's the reason for separating it out?
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