Add Net::HTTP adapter with dynamic config example

examples/net_http/07_circuit_dynamic_config.rb

@@ -0,0 +1,113 @@
+# frozen_string_literal: true
+
+require "semian"
+require "semian/net_http"
+require_relative "../colors"
+
+puts "> Starting example #{__FILE__}".blue.bold
+puts
+puts "> Initialize print Semian state changes".blue.bold
+Semian.subscribe do |event, resource, scope, adapter|
+  puts "[semian] adapter=#{adapter} scope=#{scope} event=#{event} " \
+    "resource_name=#{resource.name} resource=#{resource}".gray
+end
+
+SEMIAN_PARAMETERS = {
+  circuit_breaker: true,
+  success_threshold: 3,
+  error_threshold: 1,
+  error_timeout: 5,
+  bulkhead: false,
+  dynamic: true,
+  open_circuit_server_errors: true,
+}
+
+uri = URI("http://example.com:80")
+
+puts "> Configure Circuit breaker for Net::HTTP".blue.bold
+Semian::NetHTTP.semian_configuration = proc do |host, port|
+  puts "[semian/http] invoked config for host=#{host}(#{host.class}) port=#{port}(#{port.class})".gray
+
+  if host == "example.com"
+    puts "  set resource name example_com".gray
+    sub_resource_name = Thread.current[:current_semian_sub_resource_name]
+    # We purposefully do not use the port as the resource name, so that we can
+    # force the circuit to open by sending a request to an invalid port, e.g. 81
+    SEMIAN_PARAMETERS.merge(name: "example_com_#{sub_resource_name}")
+  else
+    puts "  skip semian initialization".gray
+    nil
+  end
+end
+
+puts "> Test requests".blue.bold
+puts " >> 1. Request to http://example.com - success".cyan
+Thread.current[:current_semian_sub_resource_name] = "sub_resource_1"
+response = Net::HTTP.get_response(uri)
+puts "  > Response status: #{response.code}"
+puts
+
+puts " >> 2. Request to http://example.com - success".cyan
+Thread.current[:current_semian_sub_resource_name] = "sub_resource_2"
+response = Net::HTTP.get_response(uri)
+puts "  > Response status: #{response.code}"
+puts
+
+puts "> Review semian state:".blue.bold
+resource1 = Semian["nethttp_example_com_sub_resource_1"]
+puts "resource_name=#{resource1.name} resource=#{resource1} " \
+  "closed=#{resource1.closed?} open=#{resource1.open?} " \
+  "half_open=#{resource1.half_open?}".gray
+resource2 = Semian["nethttp_example_com_sub_resource_2"]
+puts "resource_name=#{resource2.name} resource=#{resource2} " \
+  "closed=#{resource2.closed?} open=#{resource2.open?} " \
+  "half_open=#{resource2.half_open?}".gray
+puts
+
+puts "> Test request errors".blue.bold
+puts " >> 3. Request to http://example.com - fail".magenta
+Thread.current[:current_semian_sub_resource_name] = "sub_resource_1"
+begin
+  # We use a different port to make the connection fail
+  Net::HTTP.start(uri.host, 81, open_timeout: 1) do |http|
+    http.request_get(uri)
+  end
+rescue => e
+  puts "   >> Could not connect: #{e.message}".brown
+  puts
+end
+
+puts " >> 4. Request to http://example.com - success".cyan
+Thread.current[:current_semian_sub_resource_name] = "sub_resource_2"
+response = Net::HTTP.get_response(uri)
+puts "  > Response status: #{response.code}"
+puts
+
+puts "> Review semian state:".blue.bold
+resource1 = Semian["nethttp_example_com_sub_resource_1"]
+puts "resource_name=#{resource1.name} resource=#{resource1} " \
+  "closed=#{resource1.closed?} open=#{resource1.open?} " \
+  "half_open=#{resource1.half_open?}".gray
+resource2 = Semian["nethttp_example_com_sub_resource_2"]
+puts "resource_name=#{resource2.name} resource=#{resource2} " \
+  "closed=#{resource2.closed?} open=#{resource2.open?} " \
+  "half_open=#{resource2.half_open?}".gray
+puts
+
+puts " >> 5. Request to http://example.com - fail".magenta
+begin
+  Thread.current[:current_semian_sub_resource_name] = "sub_resource_1"
+  Net::HTTP.get_response(uri)
+rescue Net::CircuitOpenError => e
+  puts "   >> Semian is open: #{e.message}".brown
+  puts "   !!! Semian open for sub_resource_1 and no request made to example.com:80 !!!".red.bold
+end
+puts
+
+puts " >> 6. Request to http://example.com - success".cyan
+Thread.current[:current_semian_sub_resource_name] = "sub_resource_2"
+response = Net::HTTP.get_response(uri)
+puts "  > Response status: #{response.code}"
+puts
+
+puts "> That's all Folks!".green