Create loopback aliases for inter-container communication

README.md

@@ -106,6 +106,7 @@ dory:
   # doesn't exist.
   dnsmasq:
     enabled: true
+    autostart: false       # true to set the container to restart unless stopped (e.g. after reboot)
     domains:               # array of domains that will be resolved to the specified address
       - domain: docker     # you can set '#' for a wildcard
         address: 127.0.0.1 # return for queries against the domain
@@ -120,6 +121,7 @@ dory:
     service_start_delay: 5  # seconds to wait after restarting systemd services
   nginx_proxy:
     enabled: true
+    autostart: false   # true to set the container to restart unless stopped (e.g. after reboot)
     container_name: dory_dinghy_http_proxy
     https_enabled: true
     ssl_certs_dir: ''  # leave as empty string to use default certs
@@ -130,6 +132,15 @@ dory:
     enabled: true
     nameserver: 127.0.0.1
     port: 53  # port where the nameserver listens. On linux it must be 53
+
+  aliases:
+    enabled: true 
+    autostart: false  # true to make the aliases persist across restarts
+    # addresses:
+    #   To allow containers to talk to each other by their names,
+    #   set dnsmasq.domains[].address to a private IP and add it here
+    #   (Supported on MacOS only)
+    #   - <ip>
 ```
 
 #### Upgrading existing config file

bin/dory

@@ -362,8 +362,22 @@ class DoryBin < Thor
         puts "resolv disabled in config file".yellow
       end
     end
+
+    if services.include?('aliases')
+      if aliases_enabled?(settings)
+        puts "Aliases enabled in config file".green if options[:verbose]
+        if Dory::Alias.configure
+          puts "Successfully created loopback aliases".green
+        else
+          puts "Error configuring aliases".red
+        end
+      else
+        puts "Aliases disabled in config file".yellow
+      end
+    end
   end
 
+
   def exec_status(_options)
     puts "Reading settings file at '#{Dory::Config.filename}'".green if options[:verbose]
     settings = Dory::Config.settings
@@ -391,6 +405,17 @@ class DoryBin < Thor
     else
       puts "[*] Resolv is not configured".red
     end
+
+    if !aliases_enabled?(settings)
+      puts "[*] Aliases are disabled in config file".yellow
+    else
+      addresses = Dory::Alias::check
+      if addresses.any?
+        puts "[*] Aliases:  configured for address(es) #{addresses.join(", ")}".green
+      else
+        puts "[*] No aliases are configured".red
+      end
+    end
   end
 
   def exec_down(options, services)
@@ -400,6 +425,18 @@ class DoryBin < Thor
     puts "Reading settings file at '#{Dory::Config.filename}'".green if options[:verbose]
     settings = Dory::Config.settings
 
+    if services.include?('aliases')
+      if Dory::Alias.clean
+        if aliases_enabled?(settings)
+          puts "Loopback aliases removed".green
+        else
+          puts "Aliases disabled in config file".yellow
+        end
+      else
+        puts "Unable to remove loopback aliases".red
+      end
+    end
+
     if services.include?('resolv')
       if Dory::Resolv.clean
         if resolv_enabled?(settings)
@@ -471,12 +508,16 @@ class DoryBin < Thor
     settings[:dory][:resolv][:enabled]
   end
 
+  def aliases_enabled?(settings)
+    settings[:dory][:aliases][:enabled]
+  end
+
   def resolv_disabled?(settings)
     !resolv_enabled?(settings)
   end
 
   def valid_services
-    %w[proxy dns resolv]
+    %w[proxy dns resolv aliases]
   end
 
   def canonical_service(service)
@@ -488,7 +529,8 @@ class DoryBin < Thor
       'dns' => 'dns',
       'dnsmasq' => 'dns',
       'resolv' => 'resolv',
-      'resolve' => 'resolv'
+      'resolve' => 'resolv',
+      'aliases' => 'aliases'
     }[service]
   end
 

lib/dory/alias.rb

@@ -0,0 +1,49 @@
+module Dory
+  module Alias
+    def self.get_module
+      return Dory::Alias::Macos if Os.macos?
+      Dory::Alias::Linux
+    end
+
+    def self.configure()
+      puts "Requesting sudo to create loopback aliases".green
+      self.each_address lambda {|address|
+        puts "[DEBUG] creating loopback alias for #{address}" if Dory::Config.debug?
+        self.get_module.configure(address)
+      }
+    end
+
+    def self.clean()
+      puts "Requesting sudo to remove loopback aliases".green
+      self.each_address lambda {|address|
+        puts "[DEBUG] creating loopback alias for #{address}" if Dory::Config.debug?
+        self.get_module.clean(address)
+      }
+    end
+
+    def self.check()
+      addresses = []
+      self.each_address lambda {|address|
+        addresses.push(address) if self.get_module.check(address)
+      }
+      addresses
+    end
+
+    def self.each_address(cb)
+      success = true
+      self.addresses.each do |address|
+        begin 
+          cb.call(address)
+        rescue Exception => error
+          puts error.message.red
+          success = false
+        end
+      end
+      success
+    end
+
+    def self.addresses
+      Dory::Config.settings[:dory][:aliases][:addresses] || []
+    end
+  end
+end

lib/dory/alias/linux.rb

@@ -0,0 +1,14 @@
+module Dory
+  module Alias
+    module Linux
+      message = 'Loopback alias creation not implemented on Linux. Please create an alias using your distribution\'s supported configuration mechanism'
+
+      def self.configure(address)
+        puts message.yellow
+      end
+      def self.clean(address)
+        puts message.yellow
+      end
+    end
+  end
+end

lib/dory/alias/macos.rb

@@ -0,0 +1,65 @@
+module Dory
+  module Alias
+    module Macos
+      def self.plist_file(address)
+        "/Library/LaunchDaemons/com.user.lo0-loopback-#{address.gsub('.', '-')}.plist"
+      end
+
+      def self.plist(address) 
+        <<-PLIST
+        <?xml version="1.0" encoding="UTF-8"?>
+        <!DOCTYPE plist PUBLIC -//Apple Computer//DTD PLIST 1.0//EN http://www.apple.com/DTDs/PropertyList-1.0.dtd >
+        <plist version="1.0">
+        <dict>
+          <key>Label</key>
+          <string>com.user.lo0-loopback</string>
+          <key>ProgramArguments</key>
+          <array>
+            <string>/sbin/ifconfig</string>
+            <string>lo0</string>
+            <string>alias</string>
+            <string>#{address}</string>
+          </array>
+          <key>RunAtLoad</key> <true/>
+          <key>Nice</key>
+          <integer>10</integer>
+          <key>KeepAlive</key>
+          <false/>
+          <key>AbandonProcessGroup</key>
+          <true/>
+          <key>StandardErrorPath</key>
+          <string>/var/log/loopback-alias.log</string>
+          <key>StandardOutPath</key>
+          <string>/var/log/loopback-alias.log</string>
+        </dict>
+        </plist>
+        PLIST
+      end
+
+      def self.autostart
+        Dory::Config.settings[:dory][:aliases][:autostart]
+      end
+
+      def self.configure(address)
+        Bash.run_command("sudo /sbin/ifconfig lo0 alias #{Shellwords.escape(address)} >/dev/null")
+
+        if self.autostart && !File.exist?(self.plist_file(address))
+          Bash.run_command("echo -e '#{Bash.escape_single_quotes(self.plist(address))}' | sudo /usr/bin/tee #{Shellwords.escape(self.plist_file(address))} >/dev/null")
+        end
+      end
+
+      def self.clean(address)
+        Bash.run_command("sudo /sbin/ifconfig lo0 delete #{Shellwords.escape(address)} >/dev/null")
+
+        if File.exist?(self.plist_file(address))
+          Bash.run_command("sudo rm #{Shellwords.escape(self.plist_file(address))} >/dev/null")
+        end
+      end
+
+      def self.check(address)
+        result = Bash.run_command("/sbin/ifconfig lo0")
+        result.stdout.include? "inet #{address}"
+      end
+    end
+  end
+end

lib/dory/config.rb

@@ -61,6 +61,8 @@ def self.default_yaml
             enabled: true
             nameserver: 127.0.0.1
             port: 53  # port where the nameserver listens. On linux it must be 53
+          aliases:
+            enabled: false
       ).split("\n").map{|s| s.sub(' ' * 8, '')}.join("\n")
     end
 
@@ -72,7 +74,7 @@ def self.settings(filename = self.filename)
       if File.exist?(filename)
         defaults = self.default_settings.dup
         config_file_settings = YAML.load_file(filename).with_indifferent_access
-        [:dnsmasq, :nginx_proxy, :resolv].each do |service|
+        [:dnsmasq, :nginx_proxy, :resolv, :aliases].each do |service|
           defaults[:dory][service].merge!(config_file_settings[:dory][service] || {})
         end
         defaults[:dory][:debug] = config_file_settings[:dory][:debug]

lib/dory/dnsmasq.rb

@@ -110,11 +110,15 @@ def self.old_domain
     def self.old_address
       Dory::Config.settings[:dory][:dnsmasq][:address]
     end
-
+    
     def self.address(addr)
       Dory::Dinghy.match?(addr) ? Dory::Dinghy.ip : addr
     end
 
+    def self.autostart
+      Dory::Config.settings[:dory][:dnsmasq][:autostart]
+    end
+
     def self.domain_addr_arg_string
       if self.old_domain
         "#{Shellwords.escape(self.old_domain)} #{Shellwords.escape(self.address(self.old_address))}"
@@ -127,6 +131,7 @@ def self.domain_addr_arg_string
 
     def self.run_command
       "docker run -d -p #{self.port}:#{self.port}/tcp -p #{self.port}:#{self.port}/udp " \
+      "--restart=#{self.autostart ? 'unless-stopped' : 'no'} " \
       "--name=#{Shellwords.escape(self.container_name)} " \
       "--cap-add=NET_ADMIN #{Shellwords.escape(self.dnsmasq_image_name)} " \
       "#{self.domain_addr_arg_string}"

lib/dory/proxy.rb

@@ -42,8 +42,13 @@ def self.http_port
       Dory::Config.settings[:dory][:nginx_proxy][:port]
     end
 
+    def self.autostart
+      Dory::Config.settings[:dory][:nginx_proxy][:autostart]
+    end
+
     def self.run_command
       "docker run -d -p #{http_port}:80 #{self.tls_arg} #{self.certs_arg} "\
+        "--restart=#{self.autostart ? 'unless-stopped' : 'no'} " \
         "-v /var/run/docker.sock:/tmp/docker.sock -e " \
         "'CONTAINER_NAME=#{Shellwords.escape(self.container_name)}' --name " \
         "'#{Shellwords.escape(self.container_name)}' " \