rough draft for systemd export support

http://0pointer.de/blog/projects/systemd.html

This adds support for exporting systemd targets and services.  The
structure is based on the existing upstart support.

Quality is draft and expected to refine in the coming weeks.

One Foremanism that is not respected by these export templates is the
usual log output location, instead stdout and stderr go to syslog.

spec/foreman/export/systemd_spec.rb

@@ -0,0 +1,87 @@
+require "spec_helper"
+require "foreman/engine"
+require "foreman/export/systemd"
+require "tmpdir"
+
+describe Foreman::Export::Systemd, :fakefs do
+  let(:procfile)  { write_procfile("/tmp/app/Procfile") }
+  let(:formation) { nil }
+  let(:engine)    { Foreman::Engine.new(:formation => formation).load_procfile(procfile) }
+  let(:options)   { Hash.new }
+  let(:systemd)   { Foreman::Export::Systemd.new("/tmp/init", engine, options) }
+
+  before(:each) { load_export_templates_into_fakefs("systemd") }
+  before(:each) { stub(systemd).say }
+
+  it "exports to the filesystem" do
+    systemd.export
+
+    File.read("/tmp/init/app.target").should          == example_export_file("systemd/app.target")
+    File.read("/tmp/init/app-alpha.target").should    == example_export_file("systemd/app-alpha.target")
+    File.read("/tmp/init/app-alpha-1.service").should == example_export_file("systemd/app-alpha-1.service")
+    File.read("/tmp/init/app-bravo.target").should    == example_export_file("systemd/app-bravo.target")
+    File.read("/tmp/init/app-bravo-1.service").should == example_export_file("systemd/app-bravo-1.service")
+  end
+
+  it "cleans up if exporting into an existing dir" do
+    mock(FileUtils).rm("/tmp/init/app.target")
+    mock(FileUtils).rm("/tmp/init/app-alpha.target")
+    mock(FileUtils).rm("/tmp/init/app-alpha-1.service")
+    mock(FileUtils).rm("/tmp/init/app-bravo.target")
+    mock(FileUtils).rm("/tmp/init/app-bravo-1.service")
+
+    systemd.export
+    systemd.export
+  end
+
+  it "includes environment variables" do
+    engine.env['KEY'] = 'some "value"'
+    systemd.export
+    File.read("/tmp/init/app-alpha-1.service").should =~ /KEY=some "value"$/
+  end
+
+  context "with a formation" do
+    let(:formation) { "alpha=2" }
+
+    it "exports to the filesystem with concurrency" do
+      systemd.export
+
+      File.read("/tmp/init/app.target").should             == example_export_file("systemd/app.target")
+      File.read("/tmp/init/app-alpha.target").should       == example_export_file("systemd/app-alpha.target")
+      File.read("/tmp/init/app-alpha-1.service").should    == example_export_file("systemd/app-alpha-1.service")
+      File.read("/tmp/init/app-alpha-2.service").should    == example_export_file("systemd/app-alpha-2.service")
+      File.exists?("/tmp/init/app-bravo-1.service").should == false
+    end
+  end
+
+  context "with alternate templates" do
+    let(:template) { "/tmp/alternate" }
+    let(:options)  { { :app => "app", :template => template } }
+
+    before do
+      FileUtils.mkdir_p template
+      File.open("#{template}/master.target.erb", "w") { |f| f.puts "alternate_template" }
+    end
+
+    it "can export with alternate template files" do
+      systemd.export
+      File.read("/tmp/init/app.target").should == "alternate_template\n"
+    end
+  end
+
+  context "with alternate templates from home dir" do
+
+    before do
+      FileUtils.mkdir_p File.expand_path("~/.foreman/templates/systemd")
+      File.open(File.expand_path("~/.foreman/templates/systemd/master.target.erb"), "w") do |file|
+        file.puts "default_alternate_template"
+      end
+    end
+
+    it "can export with alternate template files" do
+      systemd.export
+      File.read("/tmp/init/app.target").should == "default_alternate_template\n"
+    end
+  end
+
+end

spec/resources/export/systemd/app-alpha-1.service

@@ -0,0 +1,16 @@
+[Unit]
+StopWhenUnneeded=true
+
+[Service]
+User=app
+WorkingDirectory=/tmp/app
+Environment=PORT=5000
+ExecStart=/bin/bash -lc './alpha'
+Restart=always
+StandardInput=null
+StandardOutput=syslog
+StandardError=syslog
+SyslogIdentifier=%n
+
+[Install]
+WantedBy=app-alpha.target

spec/resources/export/systemd/app-alpha-2.service

@@ -0,0 +1,16 @@
+[Unit]
+StopWhenUnneeded=true
+
+[Service]
+User=app
+WorkingDirectory=/tmp/app
+Environment=PORT=5001
+ExecStart=/bin/bash -lc './alpha'
+Restart=always
+StandardInput=null
+StandardOutput=syslog
+StandardError=syslog
+SyslogIdentifier=%n
+
+[Install]
+WantedBy=app-alpha.target

spec/resources/export/systemd/app-alpha.target

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+[Unit]
+StopWhenUnneeded=true
+
+[Install]
+WantedBy=app.target

spec/resources/export/systemd/app-bravo-1.service

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+[Unit]
+StopWhenUnneeded=true
+
+[Service]
+User=app
+WorkingDirectory=/tmp/app
+Environment=PORT=5100
+ExecStart=/bin/bash -lc './bravo'
+Restart=always
+StandardInput=null
+StandardOutput=syslog
+StandardError=syslog
+SyslogIdentifier=%n
+
+[Install]
+WantedBy=app-bravo.target

spec/resources/export/systemd/app-bravo.target

@@ -0,0 +1,5 @@
+[Unit]
+StopWhenUnneeded=true
+
+[Install]
+WantedBy=app.target

spec/resources/export/systemd/app.target

@@ -0,0 +1 @@
+[Unit]