jtimberman's Code Blog

Chef, Ops, Ruby, Linux/Unix. Opinions are mine, not my employer's (Chef).

Chef Repository Berkshelf Conversion

I’ve been managing my personal systems with Chef since Chef was created, though I didn’t always use the same chef-repo for them. For about two years though, I’ve used pretty much the same repository, which has grown and accumulated cruft over time. Fortunately since it’s only me working on it, and I only have a few systems, it is really easy to make drastic changes.

I have a number of to do items that I’ve put off, so this weekend I decided to spend some time cleaning house, and convert the repository to have cookbooks managed by Berkshelf.

Rationale

There are other cookbook management tools, including the built in “knife cookbook site install”, librarian-chef, and whisk. I have used the knife command as long as it has existed, and it worked well for awhile. The buzz in the community since the Chef Summit has been around “library” vs “application” cookbooks, especially in conjunction with Berkshelf so I thought I’d give it a go.

Before Berkshelf

Before I started on this migration, here are some numbers about cookbooks in my chef-repo.

  • 113 total cookbooks
  • 33 “chef-vendor” branches (knife cookbook site install creates a branch for each cookbook)
  • 50 “cookbook site” tags

Overall, I had about a half dozen cookbooks that I actually modified from their “upstream” versions on the community site. Most of those customizations were adding munin plugins, changing a couple minor settings in a template, or long term workarounds that are actually fixed in the current released versions.

The Conversion

The conversion was fairly straight-forward. It required some preparation:

  • Determine the cookbooks that would be managed by Berkshelf.
  • Refactor customizations into “application” cookbooks or otherwise.
  • Remove all those cookbooks, and the completely unused cookbooks.

Cookbooks in Berkshelf

Determining the cookbooks that would be managed by Berkshelf was simple. I started with all the cookbooks that had been installed via knife cookbook site install. Since the command creates a branch for each one, I had a nice list already. I did review that for cookbooks I know I wasn’t using anymore, or didn’t plan to use for long, to simplify matters.

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git branch | grep 'chef-vendor' | awk -F- '{print $3}'

I also looked at the cookbooks that are applied to node’s expanded run lists. This knife exec one-liner will return such a list.

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knife exec -E "nodes.find('recipes:*').map {|n| n[:recipes]}.flatten.map {|r| r.gsub(/::.*/, '')}.sort.uniq"

Refactoring Customization

My repository has a fair amount of customization to the cookbooks from the community site. Rather than go through all the changes, I’ll summarize with the more interesting parts.

First, I use Samba for filesharing from an Ubuntu server. I originally changed the samba::server recipe so the services used upstart as the provider and set a start_command on Ubuntu, which looked like this (s is smbd or nmbd):

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service s do
  pattern "smbd|nmbd" if node["platform"] =~ /^arch$/
  provider Chef::Provider::Service::Upstart if platform?("ubuntu")
  start_command "/usr/bin/service #{s} start" if platform?("ubuntu")
  action [:enable, :start]
end

The upstream cookbook doesn’t have this change, so I added an “application” cookbook, housepub-samba, which has this as the default recipe:

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["smbd", "nmbd"].each do |s|
  srv = resource("service[#{s}]")
  srv.provider Chef::Provider::Service::Upstart
  srv.start_command "/usr/bin/service #{s} start"
end if platform?("ubuntu")

For each of the Samba services, we look up the resource in the resource collection, then change the provider to upstart, and set the start_command to use upstart’s service command.

Next, I use OpenVPN. I also want to modify the template used for the /etc/openvpn/server.conf and /etc/openvpn/server.up.sh resources. Again, I create an “application” cookbook, housepub-openvpn, and the default recipe looks like this:

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resources("template[/etc/openvpn/server.conf]").cookbook "housepub-openvpn"
resources("template[/etc/openvpn/server.up.sh]").cookbook "housepub-openvpn"

This is a shorter form of what was done for Samba’s services above. The #resources method does the lookup and returns the resource, and any of the resource parameter attributes can be used as a method, so I send the cookbook method to both template resources, setting this cookbook, housepub-openvpn as the cookbook that contains the template to use. Then, I copy my customized templates into cookbooks/housepub-openvpn/templates/default, and Chef will do the right thing.

Other cookbook changes I made were:

  • Change the data bag name used in djbdns::internal_server, which I changed back so I could use the upstream recipe.
  • Add munin plugins to various cookbooks. As I’m planning to move things to Graphite, this is unnecessary and removed.
  • A few of my OS X cookbooks have the plist file for use with mac_os_x_plist LWRP. These are simply moved to my workstation data bag.

Finally, one special case is Fletcher Nichol’s rbenv cookbook. The rbenv::user_install recipe manages /etc/profile.d/rbenv.sh, which requires root privileges. However, on my workstations where I use this particular cookbook, I run Chef as my user, so I had to comment this resource out. To allow for a non-privileged user running Chef, the better approach is to determine whether to manage that file by using an attribute, so I opened a pull request, which is now merged. Now I just have the attribute set to false in my workstation role, and can use the cookbook unmodified.

Remove Unused and Berkshelf Cookbooks

Removing the unused cookbooks, and the cookbooks managed by Berkshelf was simple. First, each cookbook gained an entry in the Berksfile. For example, apache2.

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cookbook "apache2"

Next, the cookbook was deleted from the Chef Server. I did this, purging all versions, because I planned to upload all the cookbooks as resolved by Berkshelf.

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knife cookbook delete -yap apache2

Finally, I removed the cookbook from the git repository.

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git rm -r cookbooks/apache2
git add Berksfile
git commit -m 'apache2 is managed by Berkshelf'

The cookbooks that I didn’t plan to use, I simply didn’t add to Berkshelf, and removed them all in one commit.

After Berkshelf

The net effect of this change is a simpler, easier to manage repository. I now have only 23 cookbooks in my cookbooks directory. Some of those are candidates for refactoring and updating to the upstream ones, I just didn’t get to that yet. Most of them are “internal” cookbooks that aren’t published, since they’re specific for my internal network, such as my housepub-samba or housepub-openvpn cookbooks.

On my Chef Server, I have 90 total cookbooks, which means 67 are managed by Berkshelf. I have 62 entries in my Berksfile, and some of those are dependencies of others, which means that can be refactored some as well.

The workflow is simpler, and there’s fewer moving parts to worry about changing. I think this is a net positive for this since I do it in my free time. However, there’s a couple of issues, which should be addressed in Berkshelf soon.

First, Berkshelf issue #190, which would have berks update take a single cookbook to update. Currently, it has to update all the cookbooks, and this takes time for impatient people.

Second, issue #191, which would allow berks upload to take a single cookbook to upload. Normally, one could just use knife cookbook upload, but the directory where Berkshelf stores cookbooks it is managing are not located in the cookbook_path, and the knife command uses the directory name a the cookbook name. Berkshelf creates directories like ~/.berkshelf/cookbooks/apache2-1.3.0, so the way to upload Berkshelf managed cookbooks is all together with the berks upload command. This isn’t a huge deal for me as I already uploaded all the cookbooks I’ve been using once.

All in all, I am happy with this workflow, though. It is simple and hassle-free for me. Plus, I have more flexibility for maintaining my additional non-Opscode cookbooks.

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