Writing your own Hammer plugin¶ ↑
In this tutorial we will create a simple hello world plugin.
Hammer plugins are nothing but gems. Details on how to build a gem can be found for example at rubygems.org. In the first part of this tutorial we will briefly guide you through the process of creating a very simple gem. First of all you will need the rubygems package installed on your system.
Create the basic gem structure in a project subdirectory of your choice:
$ cd ./my_first_hammer_plugin/ $ touch Gemfile $ touch hammer_cli_hello.gemspec $ mkdir -p lib/hammer_cli_hello $ touch lib/hammer_cli_hello.rb $ touch lib/hammer_cli_hello/version.rb
Example Gemfile
:
source "https://rubygems.org" gemspec
Example hammer_cli_hello.gemspec
file:
$:.unshift File.expand_path("../lib", __FILE__) require "hammer_cli_hello/version" Gem::Specification.new do |s| s.name = "hammer_cli_hello" s.authors = ["Me"] s.version = HammerCLIHello.version.dup s.platform = Gem::Platform::RUBY s.summary = %q{Hello world commands for Hammer} s.files = Dir['lib/**/*.rb'] s.require_paths = ["lib"] s.add_dependency 'hammer_cli', '>= 0.0.6' end
More details about the gemspec structure is again at rubygems.org.
We'll have to specify the plugin version in lib/hammer_cli_hello/version.rb
:
module HammerCLIHello def self.version @version ||= Gem::Version.new '0.0.1' end end
This should be enough for creating a minimalist gem. Let's build and install it.
$ gem build ./hammer_cli_hello.gemspec $ gem install hammer_cli_hello-0.0.1.gem
Place your module's config file into ~/.hammer/cli.modules.d/hello_world.yml
.
:hello: :enable_module: true
Verify the installation by running:
$ hammer -v > /dev/null
You should see a message saying that your module was loaded (second line in the sample output).
[ INFO 2013-10-16 11:19:06 Init] Initialization of Hammer CLI (0.1.0) has started... [ INFO 2013-10-16 11:19:06 Init] Extension module hammer_cli_hello loaded [ INFO 2013-10-16 11:19:06 Init] Configuration from the file /root/.hammer/cli_config.yml has been loaded [ INFO 2013-10-16 11:19:06 Init] Configuration from the file /root/.hammer/cli.modiles.d/hello.yml has been loaded [ INFO 2013-10-16 11:19:06 HammerCLI::MainCommand] Called with options: {"verbose"=>true}
Done. Your first hammer plugin is installed. Unfortunately it does not contain any commands yet. So let's start adding some to finally enjoy real results.
Optionally you can add a Rakefile and build and install the gem with rake install
# ./Rakefile require 'bundler/gem_tasks'