Add hosts file modification

Gemfile

@@ -2,3 +2,5 @@ source 'https://rubygems.org'
 
 # Specify your gem's dependencies in linux_admin.gemspec
 gemspec
+
+gem "more_core_extensions", "=1.1.0", :git => "git://github.com/ManageIQ/more_core_extensions.git", :tag => "v1.1.0"

lib/linux_admin.rb

@@ -12,6 +12,7 @@
 
 require 'linux_admin/service'
 require 'linux_admin/disk'
+require 'linux_admin/hosts'
 require 'linux_admin/partition'
 require 'linux_admin/distro'
 require 'linux_admin/system'

lib/linux_admin/hosts.rb

@@ -0,0 +1,73 @@
+class LinuxAdmin
+  class Hosts < LinuxAdmin
+    attr_accessor :filename
+    attr_accessor :raw_lines
+    attr_accessor :parsed_file
+
+    def initialize(filename = "/etc/hosts")
+      @filename = filename
+      self.reload
+    end
+
+    def reload
+      @raw_lines = File.read(@filename).split("\n")
+      parse_file
+    end
+
+    def save
+      cleanup_empty
+      @raw_lines = assemble_lines
+      File.write(@filename, @raw_lines.join("\n"))
+    end
+
+    def update_entry(address, hostname, comment = nil)
+      # Delete entries for this hostname first
+      @parsed_file.each {|i| i[:hosts].to_a.delete(hostname)}
+
+      # Add entry
+      line_number = @parsed_file.find_path(address).first
+
+      if line_number.blank?
+        @parsed_file.push({:address => address, :hosts => [hostname], :comment => comment})
+      else
+        new_hosts = @parsed_file.fetch_path(line_number, :hosts).to_a.push(hostname)
+        @parsed_file.store_path(line_number, :hosts, new_hosts)
+        @parsed_file.store_path(line_number, :comment, comment) if comment
+      end
+    end
+
+  private
+    def parse_file
+      @parsed_file = []
+      @raw_lines.each { |line| @parsed_file.push(parse_line(line.strip)) }
+      @parsed_file.delete_blank_paths
+    end
+
+    def parse_line(line)
+      data, comment   = line.split("#", 2)
+      address, hosts  = data.to_s.split(" ", 2)
+      hostnames       = hosts.to_s.split(" ")
+
+      { :address => address.to_s, :hosts => hostnames, :comment => comment.to_s.strip, :blank => line.blank?}
+    end
+
+    def cleanup_empty
+      @parsed_file.each do |h|
+        h.delete(:hosts) if h[:address].blank?
+        h.delete(:address) if h[:hosts].blank?
+      end
+
+      @parsed_file.delete_blank_paths
+    end
+
+    def assemble_lines
+      @parsed_file.each_with_object([]) { |l, a| a.push(l[:blank] ? "" : build_line(l[:address], l[:hosts], l[:comment])) }
+    end
+
+    def build_line(address, hosts, comment)
+      line = [address.to_s.ljust(16), hosts.to_a.uniq]
+      line.push("##{comment}") if comment
+      line.flatten.join(" ").strip
+    end
+  end
+end

linux_admin.gemspec

@@ -33,6 +33,6 @@ registration, updates, etc.
 
   spec.add_dependency "activesupport",        "< 4.0"
   spec.add_dependency "inifile",              "~> 2.0.2"
-  spec.add_dependency "more_core_extensions"
+  spec.add_dependency "more_core_extensions", "~> 1.1.0"
   spec.add_dependency "nokogiri"
 end

spec/hosts_spec.rb

@@ -0,0 +1,55 @@
+require 'spec_helper'
+
+describe LinuxAdmin::Hosts do
+  etc_hosts = "\n #Some Comment\n127.0.0.1\tlocalhost localhost.localdomain # with a comment\n127.0.1.1  my.domain.local"
+  before do
+    File.stub(:read).and_return(etc_hosts)
+    @instance = LinuxAdmin::Hosts.new
+  end
+
+  describe "#reload" do
+    it "sets raw_lines" do
+      expected_array = ["", " #Some Comment", "127.0.0.1\tlocalhost localhost.localdomain # with a comment", "127.0.1.1  my.domain.local"]
+      expect(@instance.raw_lines).to eq(expected_array)
+    end
+
+    it "sets parsed_file" do
+      expected_hash = [{:blank=>true}, {:comment=>"Some Comment"}, {:address=>"127.0.0.1", :hosts=>["localhost", "localhost.localdomain"], :comment=>"with a comment"}, {:address=>"127.0.1.1", :hosts=>["my.domain.local"]}]
+      expect(@instance.parsed_file).to eq(expected_hash)
+    end
+  end
+
+  describe "#update_entry" do
+    it "removes an existing entry and creates a new one" do
+      expected_hash = [{:blank=>true}, {:comment=>"Some Comment"}, {:address=>"127.0.0.1", :hosts=>["localhost", "localhost.localdomain"], :comment=>"with a comment"}, {:address=>"127.0.1.1", :hosts=>[]}, {:address=>"1.2.3.4", :hosts=>["my.domain.local"], :comment=>nil}]
+      @instance.update_entry("1.2.3.4", "my.domain.local")
+      expect(@instance.parsed_file).to eq(expected_hash)
+    end
+
+    it "updates an existing entry" do
+      expected_hash = [{:blank=>true}, {:comment=>"Some Comment"}, {:address=>"127.0.0.1", :hosts=>["localhost", "localhost.localdomain", "new.domain.local"], :comment=>"with a comment"}, {:address=>"127.0.1.1", :hosts=>["my.domain.local"]}]
+      @instance.update_entry("127.0.0.1", "new.domain.local")
+      expect(@instance.parsed_file).to eq(expected_hash)
+    end
+  end
+
+  describe "#save" do
+    before do
+      File.stub(:write)
+    end
+
+    it "properly generates file with new content" do
+      expected_array = ["", "#Some Comment", "127.0.0.1        localhost localhost.localdomain #with a comment", "127.0.1.1        my.domain.local", "1.2.3.4          test"]
+      @instance.update_entry("1.2.3.4", "test")
+      @instance.save
+      expect(@instance.raw_lines).to eq(expected_array)
+    end
+
+    it "properly generates file with removed content" do
+      expected_array = ["", "#Some Comment", "127.0.0.1        localhost localhost.localdomain my.domain.local #with a comment"]
+      @instance.update_entry("127.0.0.1", "my.domain.local")
+      @instance.save
+      expect(@instance.raw_lines).to eq(expected_array)
+    end
+  end
+end