[chef] Re: idempotent lwrp behaviour

[Greg Zapp < >]

Hi Again,

It's actually on page 14.  The gist is that you check the resources after converging the context for updated resources, then you set the outer resources updated_by_last_action based on that.

Cheers,

   -Greg

On Wed, Sep 10, 2014 at 11:26 AM, Greg Zapp < " target="_blank"> > wrote:

Hi Pepov,

I'll be honest that I'm having a hard time determining exactly where you're issue is based on what's posted but.. The package resource should not be "updated_by_last_action" if the package is already installed and up to date.  This slide deck has a slide on "Nested Resources" that might be applicable to what you are doing(and if not def worth knowing) http://www.slideshare.net/geekbri/lwrp-presentation .  It involves running the nested resources in a new context and then checking that context to see if resources have been updated or not.  It's a bit gross IMHO, and there may be a better way of doing it, but it's fairly straight forward.

I hope that helps and apologise if it does not :)

-Greg

On Wed, Sep 10, 2014 at 12:31 AM, Peter Wilcsinszky < " target="_blank"> > wrote:

Hi all!

I've run into a problem, when I was trying to implement an lwrp, that does something like the artifact_package resource in https://github.com/RiotGames/artifact-cookbook

The simplified base of the lwrp looks like:

use_inline_resources

action :install

    custom_artifact_download_lwrp ...

    package ...

end

I wanted to test its idempotency, to make sure no notification will be propagated when the package is already installed. If any of the inner resources inside the custom_artifact_download_lwrp resource was modified (the file has been removed from the cache - we want to do periodic cleanup there) the notification was sent out even if the package was already installed. I wanted to force "mute" it somehow, because I want to avoid restarting services needlessly. I've naively tried:

c = custom_artifact_download_lwrp

c.updated_by_last_action(false)

But after digging into the code I've realised I can not do this, since this code runs before the resource collection is converged. So if a resource gets modified the updated flag will be true and I cannot do anything about it. Is there a way to do this?

Anyways, after reading the lwrp docs more closely, I've realized that I should do a conditional before declaring any of my resources, so ended up in doing this:

def skip_install?(name, version)

status = `dpkg -s #{name}`

status.lines.any? { |l| /^Status: install ok installed/.match l } &&

status.lines.any? { |l| /^Version: #{version}$/.match l }

end

action :install

    unless skip_install?()

        custom_artifact_download_lwrp ...

        package ...

    end

end

I'm wondering if there is a more appropriate way of checking package availability, and wheter I've ended up doing this right or missing something?

Thanks,

pepov