"And if you have n nodes that share the same run list and environment, you
can only alter one of those n nodes by altering its run list or environment
-- otherwise, the change would apply to all n nodes, no?"
No. Nodes can receive attributes by having a role with attributes in a run
list, in which case attributes are used from the role and/or by specifying
an environment when Chef is run, in which case attributes are used from the
environment. You can also set them in a recipe, which applies the
attributes to the node object itself. Finally you can just set attributes
directly against a node object by editing the node object directly in Chef
server, using something like knife node edit.
As an example I have a recipe which installs a Newrelic agent if a certain
attribute is set to true. In the production Chef environment I set the
attribute so that all production nodes have this. If I want to use newrelic
for a machine outside of production I can set that attribute on the
individual node object instead, which could be in any environment.
In your case you would put the same data from the YAML you need in a
specific attribute for the node you are altering (in JSON), and it would
change that node only.
On 6 October 2015 at 20:27, Julian C. Dunn jdunn@aquezada.com wrote:
Does this help?
- Julian
On Tue, Oct 6, 2015 at 10:13 PM, Fabien Delpierre
fabien.delpierre@gmail.com wrote:Lamont,
Your mention of tags is interesting. I'd actually never heard of them
and it
seems like there's little documentation on the topic.
Could you share some examples?On Tue, Oct 6, 2015 at 6:15 PM, Lamont Granquist lamont@chef.io wrote:
you can use tags (or normal attribute precedence level, which is how
tags
are implemented) to assign attributes directly to nodes for one-off use
cases.On 10/06/2015 01:22 PM, Yoshi Spendiff wrote:
But in Chef you have an object which represents each node, so why not
just
edit that if you want to alter individual nodes?Perhaps I'm not understanding
On 6 October 2015 at 13:18, Fabien Delpierre <
fabien.delpierre@gmail.com>
wrote:Hello folks,
I'm a user of both Puppet and Chef, I'm more familiar with and prefer
the
latter overall, but am required to use the former at work. Recently I
was
toying with the idea of moving to Chef, although it's probably not a
realistic option, but it raised a few interesting questions.
While Puppet and Chef do roughly the same thing, they do it in slightly
different ways, and Puppet has something in particular that Chef
doesn't
have, which is Hiera.If you're not familiar with Hiera, it's a simple way to apply settings
to
any number of your servers (from a single node to an entire
infrastructure
of thousands), you define the hierarchy of settings yourself -- in a
sense,
it's kind of like being able to customize Chef's attribute precedence
and
having a single environment attached to all your nodes. The link above
explains it a lot better than I can.Anyway, I was wondering how one might deal with losing Hiera when
moving
from Puppet to Chef. It seems that you could achieve similar results
with a
mix of cookbooks, roles and environments, like everything else, but at
the
cost of ending up with a lot more of them than you'd normally have.I guess a different way I might ask this is:
Imagine I have a group of servers, all configured the same way (same
run
list, same environment), and I need to change something on just one of
them.
A common scenario in my environment is having to attach YourKit to a
JVM
process.
With Puppet/Hiera, I'd just add a two-line YAML file with the same name
as that one server's FQDN, and when I run Puppet, that YAML file would
be
read at compile time and the config change applied without affecting
the
other nodes.
With Chef, I'd have to modify the node's run list or take its
environment
file, make a copy of it, modify the copy and assign that copied
environment
to the node instead of the normal env file, lest I affect the other
servers
in the same group.Hiera is also capable of aggregating data from multiple sources into a
single hash or array to be applied to a node during a Puppet agent run.Those are things that I never missed for as long as I used Chef, but
now
that I know they're out there, I'm wondering how I would handle things
without Hiera.So in short, I was wondering if anybody has thoughts on the matter.
Obviously it helps if you have some experience with both tools. I'm
far from
being a Chef expert so it's possible I'm missing something. Any input
is
appreciated. Thanks!
Fabien--
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