[PATCH 2/3] extras/proxy_pass: log exceptions leading to 502

[Eric Wong <e@80x24.org>]

It may be useful for us to track down potential errors in
our code or log when an upstream misbehaves.
---
 extras/proxy_pass.rb           |  4 +++
 test/server_helper.rb          |  6 ++--
 test/test_extras_proxy_pass.rb | 78 ++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 85 insertions(+), 3 deletions(-)
 create mode 100644 test/test_extras_proxy_pass.rb

diff --git a/extras/proxy_pass.rb b/extras/proxy_pass.rb
index 8a32cac..de6a2b1 100644
--- a/extras/proxy_pass.rb
+++ b/extras/proxy_pass.rb
@@ -189,6 +189,10 @@ class ProxyPass # :nodoc:
     res
   rescue => e
     retry if ures && ures.fail_retryable? && request_method != "POST"
+    if defined?(Yahns::Log)
+      logger = env['rack.logger'] and
+        Yahns::Log.exception(logger, 'proxy_pass', e)
+    end
     ERROR_502
   end
 
diff --git a/test/server_helper.rb b/test/server_helper.rb
index e2641a9..1ce2f29 100644
--- a/test/server_helper.rb
+++ b/test/server_helper.rb
@@ -72,10 +72,10 @@ module ServerHelper
     @ru = nil
   end
 
-  def mkserver(cfg)
+  def mkserver(cfg, srv = @srv)
     fork do
-      ENV["YAHNS_FD"] = @srv.fileno.to_s
-      @srv.autoclose = false
+      ENV["YAHNS_FD"] = srv.fileno.to_s
+      srv.autoclose = false
       yield if block_given?
       Yahns::Server.new(cfg).start.join
     end
diff --git a/test/test_extras_proxy_pass.rb b/test/test_extras_proxy_pass.rb
new file mode 100644
index 0000000..513e574
--- /dev/null
+++ b/test/test_extras_proxy_pass.rb
@@ -0,0 +1,78 @@
+# Copyright (C) 2015 all contributors <yahns-public@yhbt.net>
+# License: GPLv3 or later (https://www.gnu.org/licenses/gpl-3.0.txt)
+require_relative 'server_helper'
+
+class TestExtrasProxyPass < Testcase
+  ENV["N"].to_i > 1 and parallelize_me!
+  include ServerHelper
+
+  class ProxiedApp
+    def call(env)
+      h = [ %w(Content-Length 3), %w(Content-Type text/plain) ]
+      case env['REQUEST_METHOD']
+      when 'GET'
+        [ 200, h, [ "hi\n"] ]
+      when 'HEAD'
+        [ 200, h, [] ]
+      when 'PUT'
+        buf = env['rack.input'].read
+        [ 201, {
+          'Content-Length' => buf.bytesize.to_s,
+          'Content-Type' => 'text/plain',
+          }, [ buf ] ]
+      end
+    end
+  end
+
+  def setup
+    @srv2 = TCPServer.new(ENV["TEST_HOST"] || "127.0.0.1", 0)
+    server_helper_setup
+  end
+
+  def teardown
+    @srv2.close if defined?(@srv2) && !@srv2.closed?
+    server_helper_teardown
+  end
+
+  def test_proxy_pass
+    err, cfg, host, port = @err, Yahns::Config.new, @srv.addr[3], @srv.addr[1]
+    host2, port2 = @srv2.addr[3], @srv2.addr[1]
+    pid = mkserver(cfg) do
+      $LOAD_PATH.unshift "#{Dir.pwd}/extras"
+      require 'proxy_pass'
+      @srv2.close
+      cfg.instance_eval do
+        app(:rack, ProxyPass.new("http://#{host2}:#{port2}/")) do
+          listen "#{host}:#{port}"
+        end
+        stderr_path err.path
+      end
+    end
+
+    pid2 = mkserver(cfg, @srv2) do
+      @srv.close
+      cfg.instance_eval do
+        app(:rack, ProxiedApp.new) do
+          listen "#{host2}:#{port2}"
+        end
+        stderr_path err.path
+      end
+    end
+
+    Net::HTTP.start(host, port) do |http|
+      res = http.request(Net::HTTP::Get.new('/'))
+      assert_equal 200, res.code.to_i
+      n = res.body.bytesize
+      assert_operator n, :>, 1
+      res = http.request(Net::HTTP::Head.new('/'))
+      assert_equal 200, res.code.to_i
+      assert_equal n, res['Content-Length'].to_i
+      assert_nil res.body
+
+      res = http.put(Net::HTTP::Put.new('/'))
+    end
+  ensure
+    quit_wait pid
+    quit_wait pid2
+  end
+end
-- 
EW