Puppet for app deployment

[SyRenity]

Hi.

Has Puppet been used as deployment tool for application installations
and upgrades?

From searching the web, I found the ControlTier site, which actually
places Puppet in the software configuration level, while leaving the
app deployment for itself, Capistrano and some other tools:

http://blog.controltier.com/2009/04/new-whitepaper-achieving-fully.html

Is this the recommended and general practice, or I can get away by
using only Puppet (which I, frankly, prefer).

Thanks.

[Trevor Vaughan]

You can easily get away with only using puppet IF you don't have
cross-system dependencies.

If you have cross-system dependencies, it can still be done, but it gets hairy.

Example:

Web server A should not be turned on until database B is active.

Trevor

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[Scott Smith]

On 1/11/10 5:24 AM, SyRenity wrote:
> Hi.
>
> Has Puppet been used as deployment tool for application installations
> and upgrades?
>

I highly suggest you leave Puppet to what it does best - managing resources (files, packages, users,
mounts, etc.).

-scott

[SyRenity]

Hi.

> If you have cross-system dependencies, it can still be done, but it gets hairy.
>
> Example:
>
> Web server A should not be turned on until database B is active.

Unfortunately I do have such dependencies.

What tool would require the least dependencies on managed machines,
and would be the easiest to learn?

Thanks again.

[SyRenity]

Hi.

> I highly suggest you leave Puppet to what it does best - managing resources (files, packages, users,
> mounts, etc.).

But application can be also considered as a resource - it has files,
packages and settings.

Or there is some clear difference between system components and the
custom applications?

Regards.

[Trevor Vaughan]

Then, Puppet + ControlTier is a pretty safe bet.

If you want to do it all Puppet then you'll need to figure out how to
do cross-system semaphores or something like that.

Alternatively, you can just re-write your app initialization scripts
to check for the resources themselves. This was what I generally did
back in the early 90's with great success. This way all of your
systems are self controlled instead of relying on an external brain.

Then you could do everything with Puppet again.

Trevor

[Scott Smith]

On 1/11/10 7:46 AM, SyRenity wrote:
> But application can be also considered as a resource - it has files,
> packages and settings.
>

No, an application may be composed of resources. Puppet is perfectly capable of managing them, yes.
But the deliberate *deployment* of live software in a dynamic fashion is different.

- How do you manage killing database connections before restarting an application after you've
pushed the new code?

- How do you manage failing over load balancer VIPs and taking servers in and out of service?

- What if deploying one application requires restarting or updating configs on another application?

etc.

These things are key aspects of proper software deployment. Puppet isn't the best tool for handling
them. And that's OK, it's good to split functionality between different software.

> Or there is some clear difference between system components and the
> custom applications?
>

Yep, exactly.

-scott

[Scott Smith]

On 1/11/10 7:44 AM, SyRenity wrote:
> Unfortunately I do have such dependencies.
>
> What tool would require the least dependencies on managed machines,
> and would be the easiest to learn?
>

Check out Capistrano or Vlad (I prefer Vlad).

http://www.capify.org/index.php/Capistrano

http://rubyhitsquad.com/Vlad_the_Deployer.html

-scott

[SyRenity]

Hi.

>
> Check out Capistrano or Vlad (I prefer Vlad).
>
> http://www.capify.org/index.php/Capistrano
>
> http://rubyhitsquad.com/Vlad_the_Deployer.html

Thanks. These 2 seems to be mostly Ruby/ROR oriented - any of them
working with Java/C++ apps, or my best bet still the ControlTier?

Regards.

[Scott Smith]

SyRenity wrote:
> Thanks. These 2 seems to be mostly Ruby/ROR oriented - any of them
> working with Java/C++ apps, or my best bet still the ControlTier?
>
> Regards.
>

Control Tier uses capistrano.

-scott

[Julian Simpson]

2010/1/11 SyRenity <stas....@gmail.com>:

I haven't used Vlad but Capistrano can be used for Java app
deployment. Out of the box Capistrano is configured for deploying
Rails apps but you can configure it for other kinds of app.

http://code.google.com/p/bungeni-dspace/wiki/InstallingDspaceUsingCapistrano
http://github.com/leehambley/railsless-deploy/

>
> Regards.

>
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[geoffrey papilion]

I find that there are two problems when trying to use puppet for
application deployment.

1. Latency
2. Intersystem dependencies

Latency :

I cannot count on puppet to do what I want it to do in a low latency
fashion. Puppetrun can address the issue, but I cannot specify an
order of operations etc.. plus I have to verify that the application
has completed its roll out which mean taking a look at a report.

Intersystem dependencies:
I think this was addressed in a later thread, but I haven't found an
easy way of specifying "check db on server[1] is at this version
before running rpms on servers [5-100]", or better still "update db on
server 1 before executing package installations on servers [5-100] ".

I find that tools like capistrano, func, and pssh address these two
issues better; i know that something has run, and can immediately
address any issues as the bubble up. They aren't persistent like
puppet, which makes them difficult to use when verifying
configurations a week later. Also, they have implicit dependencies
unlike puppet(it executes from step a->z because a comes before b,
etc...), which makes writing a deployment script easier.

//geoff

[Jesús Couto]

I'm finding this discussion interesting and... depressing, as I'm trying to model an enviroment where our #1 task is to deploy Java web apps on tomcat servers.

Is there any already existant documentation/resource discussing this? The 2 objections listed are interesting, even if my enviroment usually does not have the second, the first mean that I will have a difficult time deploying on one leg and then on the other leg using Puppet, right? As in, I'm not going to know if it is being deployed on both at the same time, causing an outage, unless I do some kind of hack (change the resource in one node, then in the other...)

I'm correct? Are those arguments explained in detail somewhere?

------------------------------

Jesús Couto F.

[Silviu Paragina]

Probably a brainfart, but:
This scenario is typical and would suggest the requirement of database
resource. And this would be just enough.

Hypothetical example:
On the db machine you will have a resource like:
database
{ "mydb":
ensure => 34,
versionscript => "puppet:///modules/myapp/db_getversion.sql",
installscript => "puppet://...",
updatescript => "puppet:///...."
server => "db-serv.example.com",
username => "....",
.....
}

Now the ensure would be the required installed version of the db, or
simply true. Version script should return the current version of the db
when run. Install script creates the db, optional update updates the db
from a version to another.

The cool thing about this is that it can be added on the web app node
too as a check/dependency solver.

This or similar cases should be solvable with a similar solution.

What are your ideas about this?

Silviu

> ------------------------------------------------------------------------

[SyRenity]

I studied CT a bit, and it seems to solve such tasks perfectly.

I need much more on-hand experience of course.

Regards.

[Scott Smith]

On 1/12/10 10:23 PM, Silviu Paragina wrote:
> Probably a brainfart, but:
> This scenario is typical and would suggest the requirement of database
> resource. And this would be just enough.
>

Interesting idea, but it can't handle complex schema changes. Usually these are not "set it and
forget it" operations.

Another issue: handling sensitive data that needs to be deployed to servers. Passphrases, encrypted
file stores, etc.

Most software deployment tasks should be handled by something else.

Read this:

http://dev2ops.org/blog/2009/11/2/6-months-in-fully-automated-provisioning-revisited.html

There is a reason "Command and Control" is seperate from "Compliance and Remediation"

-scott

[Alex-SF]

Just as a point of clarification, ControlTier does not use Capistrano
though there is a bit of conceptual similarity around the notion of
"command dispatching".

[Scott Smith]

On 1/14/10 11:36 AM, Alex-SF wrote:
> Just as a point of clarification, ControlTier does not use Capistrano
> though there is a bit of conceptual similarity around the notion of
> "command dispatching".
>

You're right, as much as I read somehow I misunderstood that.

Speaking of, how many people on the list have experience with it?

-scott

[Jesús Couto]

Resurrecting this a bit... I have to check those tools (ControlTier, Capistrano), but a more higher level question: does this mean those tools sit on top of Puppet or other System Configuration Tool, doing changes to Puppet manifiests, or simply that one assumes a System Configuration Tool to keep the "system" (defined as ... dunno, everything but the applications? Packages, services, disks, etc) managed and then uses a separate language/model to deal with the particularities of web applications?

------------------------------

Jesús Couto F.

[Julian Simpson]

I tried making the app responsible for declaring its immediate
dependencies. Obviously you're going to need to have middleware etc.
on the systems before you start app deployment. But if the app knows
some of the gory detail, I think that's good.

http://www.build-doctor.com/2009/12/09/dependency-hell/