Taste Tester

Intro

Ohai!

Welcome to Taste Tester, software to manage a chef-zero instance and use it to test changes on production servers.

At its core, Taste Tester starts up a chef-zero server on localhost, uploads a repository to it, ssh’s to a remote server and points its configs to your new chef-zero instance.

Further, it keeps track of where in git you were when that happened so future uploads will do the right thing, even as you switch branches.

Taste Tester can be controlled via a variety of config-file options, and can be further customized by writing a plugin.

Synopsis

Typical usage is:

vi cookbooks/...             # Make your changes and commit locally
taste-tester impact          # Check where your changes are used
taste-tester test -s [host]  # Put host in Taste Tester mode
ssh root@[host]              # Log in to host
  # Run chef and watch it break
vi cookbooks/...             # Fix your cookbooks
taste-tester upload          # Upload the diff
ssh root@[host]
  # Run chef and watch it succeed
<Verify your changes were actually applied as intended!>
taste-tester untest [host]   # Put host back in production
                             #   (optional - will revert itself after 1 hour)

See the help for further information.

Prerequisites

• Taste Tester assumes that /etc/chef/client.rb and /etc/chef/client.pem on your servers is a symlink and that your real config is /etc/chef/client-prod.rb and /etc/chef/client-prod.pem, respectively.

• Taste Tester assumes that it’s generally safe to “go back” to production. I.e. We set things up so you can set a cronjob to un-taste-test a server after the desired amount of time, which means it must be (relatively) safe to revert back.

• Taste Tester assumes you use a setup similar to grocery-delivery in production. Specifically that you don’t use versions or environments.

• Taste Tester assumes you have password-less SSH authentication to the hosts you want to test on, i.e. SSH public/private keys, SSH certificates, Kerberos

Dependencies

• Mixlib::Config
• Colorize
• BetweenMeals
• Minitar
• Chef

Automatic Untesting

Taste Tester touches /etc/chef/test_timestamp on the remote server as far into the future as the user wants to test (default is 1h). You should have a cronjob to check the timestamp of this file, and if it is old, remove it and put the symlinks for /etc/chef/client.rb back to where they belong.

A small shell script to do this is included called taste-untester. We recommend running this at least every 15 minutes.

If you let Taste Tester setup reverse-SSH tunnels, make sure your untester is also killing the ssh tunnel whose PID is in /etc/chef/test_timestamp (taste-untester will do this for you).

Config file

The default config file is /etc/taste-tester-config.rb but you may use -c to specify another. The config file works the same as client.rb does for Chef - there are a series of keywords that take an argument and anything else is just standard Ruby.

All command-line options are available in the config file:

• debug (bool, default: false)
• timestamp (bool, default: false)
• config_file (string, default: /etc/taste-tester-config.rb)
• plugin_path (string, no default)
• repo (string, default: #{ENV['HOME']}/ops)
• testing_time (int, default: 3600)
• chef_client_command (string, default: chef-client)
• json (bool, default: false)
• skip_repo_checks (bool, default: false)
• skip_pre_upload_hook (bool, default: false)
• skip_post_upload_hook (bool, default: false)
• skip_pre_test_hook (bool, default: false)
• skip_post_test_hook (bool, default: false)
• skip_repo_checks_hook (bool, default: false)

The following options are also available:

• base_dir - The directory in the repo under which to find chef configs. Default: chef
• cookbook_dirs - An array of cookbook directories relative to base_dir. Default: ['cookbooks']
• role_dir - A directory of roles, relative to base_dir. Default: roles
• databag_dir - A directory of databags, relative to base_dir. Default: databags
• ref_file - The file to store the last git revision we uploaded in. Default: #{ENV['HOME']}/.chef/taste-tester-ref.txt
• checksum_dir - The checksum directory to put in knife.conf for users. Default: #{ENV['HOME']}/.chef/checksums
• bundle - use a single tar.gz file for transporting cookbooks, roles and databags to clients. Experimental. Value is tri-state:
  • false - server uses knife upload, client uses chef_server
  • :compatible - make server support both methods, client uses tar.gz
  • true - server only creates tar.gz, client uses tar.gz Default: false
• impact - analyze local changes to determine which hosts/roles to test. Default: false
• ssh_cmd_gen_template - Provide a command to run, whose stdout will be a vanilla ssh command Taste Tester will invoke to access test nodes. The command should be a template and will be passed the following variables:
  • jumps - any jumphost arguments supplied via -J option
  • host - the host to SSH to
  • user - the user to SSH as For example: ssh_gen %{jumps} --user %{user} %{host} Default: nil

Plugin

The plugin should be a ruby file which defines several class methods. It is class_eval()d into a Hooks class.

The following functions can optionally be defined:

• self.pre_upload(dryrun, repo, last_ref, cur_ref)

Stuff to do before we upload anything to chef-zero. Repo is a BetweenMeals::Repo object. last_ref is the last git ref we uploaded and cur_ref is the git ref the repo is currently at,

• self.post_upload(dryrun, repo, last_ref, cur_ref)

Stuff to do after we upload to chef-zero.

• self.pre_test(dryrun, repo, hosts)

Stuff to do before we put machines in test mode. hosts is an array of hostnames.

• self.test_remote_cmds(dryrun, hostname)

Additional commands to run on the remote host when putting it in test mode. Should return an array of strings. hostname is the hostname.

• self.test_remote_client_rb_extra_code(hostname)

Should return a string of additional code to include in the remote client.rb. Example uses: defining json_attribs

• self.post_test(dryrun, repo, hosts)

Stuff to do after putting all hosts in test mode.

• self.repo_checks(dryrun, repo)

Additional checks you want to do on the repo as sanity checks.

• self.find_impact(changes)

Custom implementation of impact analysis. Uses knife deps by default. May return any data structure, provided one or both of self.post_impact or self.print_impact are defined.

• self.post_impact(basic_impact)

Stuff to do after preliminary impact analysis. May be used to extend the information generated by self.find_impact, reformat the data structure, etc.

• self.print_impact(final_impact)

Custom output of calculated impact, useful if defining either of the other impact hooks. Must return a truthy value to prevent the default output from printing.

• self.post_error(dryrun, exception, mode, hostname)

A hook which will be called just before taste-tester throws an exception/exits. Passes down the exception object and the mode taste-tester was invoked with for further analysis and doing any additional logging, output, or cleanup.

Plugin example

This is an example /etc/taste-tester-plugin.rb to add a user-defined string to client-taste-tester.rb on the remote system:

Hooks.class_eval do
  def self.test_remote_client_rb_extra_code(_hostname)
    %(
      # This comment gets added to client-taste-tester.rb
      # This one too.
      )
  end
end

Be sure to pass this plugin file with -p on the command line or set it as plugin_path in your taste-tester-config.rb file.

License

See the LICENSE file.