Skip runit installation if already installed

[tdooner]

If there is an executable at the desired installation location, we can assume that runit is already installed. Unfortunately, I can't find a way to verify that the correct version is installed, but given that the version isn't configurable via attributes, it seems reasonable that when/if there ever is a new version of runit, this logic can be changed.

I don't know how to test this effectively, give the current minitest-based suite. If you have any thoughts I'd be happy to write some tests.

Cheers!

[jtimberman]

Checking that a file is executable isn't very reliable to determine if something is installed. I could touch /sbin/runit ; chmod +x /sbin/runit and this would then not work.

It would be better to move the rpm_installed to a predicate helper method (#rpm_installed?). It would also be better for the bash resource to not perform the rpm installation, and instead use another library helper to determine where the rpm_root_dir is, and use that for the install path, using rpm_package to perform the actual package installation. The bash resource could use creates with the path to the RPM, or it could use the predicate method I'm suggesting.

[tdooner]

Sorry, let me clarify. My problem isn't with the rpm detection, it's that I'm using Chef to converge an image that already has runit installed from source. I.e. there's no way to tell via rpm commands that runit is already installed.

Most Chef resources have a way to detect if they are already fulfilled by the host OS, and if so, skip doing anything too complex. But, this cookbook will download the source for runit and compile it on rhel systems if node['runit']['use_package_from_yum'] is false. For example, some other cookbooks that do this kind of check:

https://github.com/opscode-cookbooks/activemq/blob/master/recipes/default.rb#L31
https://github.com/miketheman/nginx/blob/master/recipes/source.rb#L106,L109
https://github.com/fnichol/chef-rbenv/blob/0a3018634bafe58ad21c6ee271af015220e444b9/providers/global.rb#L31

Ultimately, this is just about saving the effort of downloading + building runit every time we converge a new image even though it is already installed on our base image. Not the worst cost, but it would be nice to avoid.

Would you be more open to this if it were an attribute, e.g. default['runit']['skip_install']? Or maybe there is another way to accomplish this?

(Oh, and thanks for the speedy reply!)

[jtimberman]

Ah. Thanks for clarifying. I have some ideas... I'll make a branch.

[jtimberman]

See the commit message comments in 1d6b6af for an explanation of the helper methods added. Does that work for you?

[tdooner]

Beautiful, thanks a lot for putting that together. I'll give it a try today and I imagine it will do the trick.

[jtimberman]

Wow, I totally forgot about this. Sorry about that. Did the helpers from my branch work out for you, @tdooner?

[slyness]

Is this something that we're ready to merge or is there outstanding tasks or discussion? @jtimberman @tdooner

[jtimberman]

@slyness I think the helper methods will be more reliable than simple checking if the executable is installed. I created pull request #89 as a proposal to replace this PR.

[tdooner]

Sounds good. I'll close this in favor of #89. Thanks @jtimberman for addressing this.