tracing: add opentracing for rack and dyndnsd with configurable jaeger-client support and spanmanager

lib/dyndnsd.rb

@@ -8,6 +8,9 @@ require 'yaml'
 require 'rack'
 require 'metriks'
 require 'metriks/reporter/graphite'
+require 'opentracing'
+require 'rack/tracer'
+require 'spanmanager'
 
 require 'dyndnsd/generator/bind'
 require 'dyndnsd/updater/command_with_bind_zone'
@@ -49,12 +52,16 @@ module Dyndnsd
     end
 
     def authorized?(username, password)
-      allow = ((@users.key? username) && (@users[username]['password'] == password))
-      if !allow
-        Dyndnsd.logger.warn "Login failed for #{username}"
-        Metriks.meter('requests.auth_failed').mark
+      Helper.span('check_authorized') do |span|
+        span.set_tag('dyndnsd.user', username)
+
+        allow = Helper.user_allowed?(username, password, @users)
+        if !allow
+          Dyndnsd.logger.warn "Login failed for #{username}"
+          Metriks.meter('requests.auth_failed').mark
+        end
+        allow
       end
-      allow
     end
 
     def call(env)
@@ -95,6 +102,8 @@ module Dyndnsd
 
       setup_monitoring(config)
 
+      setup_tracing(config)
+
       setup_rack(config)
     end
 
@@ -127,15 +136,19 @@ module Dyndnsd
 
     def process_changes(hostnames, myips)
       changes = []
-      hostnames.each do |hostname|
-        # myips order is always deterministic
-        if (!@db['hosts'].include? hostname) || (@db['hosts'][hostname] != myips)
-          @db['hosts'][hostname] = myips
-          changes << :good
-          Metriks.meter('requests.good').mark
-        else
-          changes << :nochg
-          Metriks.meter('requests.nochg').mark
+      Helper.span('process_changes') do |span|
+        span.set_tag('dyndnsd.hostnames', hostnames.join(','))
+
+        hostnames.each do |hostname|
+          # myips order is always deterministic
+          if Helper.changed?(hostname, myips, @db['hosts'])
+            @db['hosts'][hostname] = myips
+            changes << :good
+            Metriks.meter('requests.good').mark
+          else
+            changes << :nochg
+            Metriks.meter('requests.nochg').mark
+          end
         end
       end
       changes
@@ -158,7 +171,7 @@ module Dyndnsd
       hostnames = params['hostname'].split(',')
 
       # check for invalid hostnames
-      invalid_hostnames = hostnames.select { |hostname| !Helper.fqdn_valid?(hostname, @domain) }
+      invalid_hostnames = hostnames.select { |h| !Helper.fqdn_valid?(h, @domain) }
       return [422, {'X-DynDNS-Response' => 'hostname_malformed'}, []] if invalid_hostnames.any?
 
       user = env['REMOTE_USER']
@@ -227,6 +240,22 @@ module Dyndnsd
       end
     end
 
+    private_class_method def self.setup_tracing(config)
+      # configure OpenTracing
+      if config.dig('tracing', 'jaeger')
+        require 'jaeger/client'
+
+        host = config['tracing']['jaeger']['host'] || '127.0.0.1'
+        port = config['tracing']['jaeger']['port'] || 6831
+        service_name = config['tracing']['jaeger']['service_name'] || 'dyndnsd'
+        OpenTracing.global_tracer = Jaeger::Client.build(
+          host: host, port: port, service_name: service_name, flush_interval: 1
+        )
+      end
+      # always use SpanManager
+      OpenTracing.global_tracer = SpanManager::Tracer.new(OpenTracing.global_tracer)
+    end
+
     private_class_method def self.setup_rack(config)
       # configure daemon
       db = Database.new(config['db'])
@@ -242,6 +271,9 @@ module Dyndnsd
         app = Responder::DynDNSStyle.new(app)
       end
 
+      trust_incoming_span = config.dig('tracing', 'trust_incoming_span') || false
+      app = Rack::Tracer.new(app, trust_incoming_span: trust_incoming_span)
+
       Rack::Handler::WEBrick.run app, Host: config['host'], Port: config['port']
     end
   end

lib/dyndnsd/database.rb

@@ -21,8 +21,10 @@ module Dyndnsd
     end
 
     def save
-      File.open(@db_file, 'w') { |f| JSON.dump(@db, f) }
-      @db_hash = @db.hash
+      Helper.span('database_save') do |_span|
+        File.open(@db_file, 'w') { |f| JSON.dump(@db, f) }
+        @db_hash = @db.hash
+      end
     end
 
     def changed?

lib/dyndnsd/generator/bind.rb

@@ -10,15 +10,15 @@ module Dyndnsd
         @additional_zone_content = config['additional_zone_content']
       end
 
-      def generate(zone)
+      def generate(db)
         out = []
         out << "$TTL #{@ttl}"
         out << "$ORIGIN #{@domain}."
         out << ''
-        out << "@ IN SOA #{@dns} #{@email_addr} ( #{zone['serial']} 3h 5m 1w 1h )"
+        out << "@ IN SOA #{@dns} #{@email_addr} ( #{db['serial']} 3h 5m 1w 1h )"
         out << "@ IN NS #{@dns}"
         out << ''
-        zone['hosts'].each do |hostname, ips|
+        db['hosts'].each do |hostname, ips|
           ips.each do |ip|
             ip = IPAddr.new(ip).native
             type = ip.ipv6? ? 'AAAA' : 'A'

lib/dyndnsd/helper.rb

@@ -17,5 +17,25 @@ module Dyndnsd
     rescue ArgumentError
       return false
     end
+
+    def self.user_allowed?(username, password, users)
+      (users.key? username) && (users[username]['password'] == password)
+    end
+
+    def self.changed?(hostname, myips, hosts)
+      # myips order is always deterministic
+      (!hosts.include? hostname) || (hosts[hostname] != myips)
+    end
+
+    def self.span(operation, &block)
+      span = OpenTracing.start_span(operation)
+      span.set_tag('component', 'dyndnsd')
+      span.set_tag('span.kind', 'server')
+      begin
+        block.call(span)
+      ensure
+        span.finish
+      end
+    end
   end
 end

lib/dyndnsd/updater/command_with_bind_zone.rb

@@ -9,14 +9,19 @@ module Dyndnsd
       end
 
       def update(zone)
-        # write zone file in bind syntax
-        File.open(@zone_file, 'w') { |f| f.write(@generator.generate(zone)) }
-        # call user-defined command
-        pid = fork do
-          exec @command
+        Helper.span('updater_update') do |span|
+          span.set_tag('dyndnsd.updater.name', self.class.name.split('::').last)
+
+          # write zone file in bind syntax
+          File.open(@zone_file, 'w') { |f| f.write(@generator.generate(zone)) }
+          # call user-defined command
+          pid = fork do
+            exec @command
+          end
+
+          # detach so children don't become zombies
+          Process.detach(pid)
         end
-        # detach so children don't become zombies
-        Process.detach(pid)
       end
     end
   end