add filter_command directive (git only)

doc/dynamic-environments/configuration.mkd

@@ -381,6 +381,24 @@ sources:
       - 'dev'
 ```
 
+### filter_command
+
+You can filter out any branch based on the result of the command specified as 'filter_command'. Non zero return
+status of the command results in a branch beeing removed. The command is passed additional environment variables
+* GIT_DIR – path to the cached git repository
+* R10K_BRANCH – brach which is beeing filtered
+* R10K_NAME – source name from r10k configuration
+
+This can be used for example for filtering out the branches with invalid gpg signature of their latests commit
+
+```yaml
+---
+sources:
+  mysource:
+    basedir: '/etc/puppet/environments'
+    filter_command: 'git verify-commit $R10K_BRANCH 2> /dev/null'
+```
+
 Examples
 --------
 

lib/r10k/source/git.rb

@@ -41,6 +41,10 @@ class R10K::Source::Git < R10K::Source::Base
   #     that will be deployed as environments.
   attr_reader :ignore_branch_prefixes
 
+  # @!attribute [r] filter_command
+  #   @return [String] Command to run to filter branches
+  attr_reader :filter_command
+
   # Initialize the given source.
   #
   # @param name [String] The identifier for this source.
@@ -61,6 +65,7 @@ def initialize(name, basedir, options = {})
     @remote = options[:remote]
     @invalid_branches = (options[:invalid_branches] || 'correct_and_warn')
     @ignore_branch_prefixes = options[:ignore_branch_prefixes]
+    @filter_command = options[:filter_command]
 
     @cache  = R10K::Git.cache.generate(@remote)
   end
@@ -115,7 +120,7 @@ def desired_contents
     environments.map {|env| env.dirname }
   end
 
-  def filter_branches(branches, ignore_prefixes)
+  def filter_branches_by_regexp(branches, ignore_prefixes)
     filter = Regexp.new("^#{Regexp.union(ignore_prefixes)}")
     branches = branches.reject do |branch|
       result = filter.match(branch)
@@ -127,14 +132,29 @@ def filter_branches(branches, ignore_prefixes)
     branches
   end
 
+  def filter_branches_by_command(branches, command)
+    branches.select do |branch|
+      result = system({'GIT_DIR' => @cache.git_dir.to_s, 'R10K_BRANCH' => branch, 'R10K_NAME' => @name.to_s}, command)
+      unless result
+        logger.warn _("Branch `%{name}:%{branch}` filtered out by filter_command %{cmd}") % {name: @name, branch: branch, cmd: command}
+      end
+      result
+    end
+  end
+
   private
 
   def branch_names
     opts = {:prefix => @prefix, :invalid => @invalid_branches, :source => @name}
     branches = @cache.branches
     if @ignore_branch_prefixes && !@ignore_branch_prefixes.empty?
-      branches = filter_branches(branches, @ignore_branch_prefixes)
+      branches = filter_branches_by_regexp(branches, @ignore_branch_prefixes)
+    end
+
+    if @filter_command && !@filter_command.empty?
+      branches = filter_branches_by_command(branches, @filter_command)
     end
+
     branches.map do |branch|
       R10K::Environment::Name.new(branch, opts)
     end

spec/unit/source/git_spec.rb

@@ -93,9 +93,45 @@
     let(:ignore_prefixes) { ['dev', 'test'] }
 
     it "filters branches" do
-      expect(subject.filter_branches(branches, ignore_prefixes)).to eq(['master', 'production', 'not_dev_test_me'])
+      expect(subject.filter_branches_by_regexp(branches, ignore_prefixes)).to eq(['master', 'production', 'not_dev_test_me'])
     end
   end
+
+  describe "filtering branches with command" do
+    let(:branches) { ['master', 'development', 'production'] }
+    let(:filter_command) { 'sh -c "[ $R10K_BRANCH != development ]"' }
+
+    it "filters branches" do
+      expect(subject.filter_branches_by_command(branches, filter_command)).to eq(['master', 'production'])
+    end
+  end
+
+  describe "generate_environments respects filter_command setting" do
+    before do
+      allow(subject.cache).to receive(:branches).and_return ['master', 'development', 'production']
+      subject.instance_variable_set(:@filter_command, '[ $R10K_BRANCH != master ]')
+    end
+
+    let(:environments) { subject.generate_environments }
+
+    it "creates an environment for each branch not filtered by filter_command" do
+      expect(subject.generate_environments.size).to eq(2)
+    end
+  end
+
+  describe "generate_environments respects filter_command setting and name" do
+    before do
+      allow(subject.cache).to receive(:branches).and_return ['master', 'development', 'production']
+      subject.instance_variable_set(:@filter_command, '[ $R10K_NAME = mysource ]')
+    end
+
+    let(:environments) { subject.generate_environments }
+
+    it "creates an environment for each branch not filtered by filter_command" do
+      expect(subject.generate_environments.size).to eq(3)
+    end
+  end
+
 end
 
 describe R10K::Source::Git, "handling invalid branch names" do