Enable puma by default in GDK

Two changes:
1. Move bin/web to bin/web_unicorn(removed PUMA switching logic)
Introduce new shadow script bin/web. Now we have 3 scripts working
together: bin/web, bin/web_puma, bin/web_unicorn

  In bin/web, it checks ENV['USE_WEB_SERVER']:
    - if value is 'puma' or value is not set, call bin/web_puma
    - if value is 'unicorn', call bin/web_unicorn
    - report error if other values given

2. Gitlab rails allow ENV setting to override timeout
    - ENV['GITLAB_RAILS_RACK_TIMEOUT'] for service_timeout
    - ENV['GITLAB_RAILS_WAIT_TIMEOUT'] for wait_timeout

bin/web

@@ -1,63 +1,21 @@
 #!/bin/sh
 
+set -e
+
 cd $(dirname $0)/..
 app_root=$(pwd)
 
-# Switch to experimental PUMA configuration
-if [ -n "${EXPERIMENTAL_PUMA}" ]; then
-  exec bin/web_puma "$@"
-fi
+case "$USE_WEB_SERVER" in
+    puma|"") # and the "" defines default
+        exec bin/web_puma "$@"
+        ;;
 
-unicorn_pidfile="$app_root/tmp/pids/unicorn.pid"
-unicorn_config="$app_root/config/unicorn.rb"
-unicorn_cmd="bundle exec unicorn_rails -c $unicorn_config -E $RAILS_ENV"
+    unicorn)
+        exec bin/web_unicorn "$@"
+        ;;
 
-get_unicorn_pid()
-{
-  local pid=$(cat $unicorn_pidfile)
-  if [ -z "$pid" ] ; then
-    echo "Could not find a PID in $unicorn_pidfile"
-    exit 1
-  fi
-  unicorn_pid=$pid
-}
-
-start()
-{
-  exec $unicorn_cmd -D
-}
-
-start_foreground()
-{
-  exec $unicorn_cmd
-}
-
-stop()
-{
-  get_unicorn_pid
-  kill -QUIT $unicorn_pid
-}
-
-reload()
-{
-  get_unicorn_pid
-  kill -USR2 $unicorn_pid
-}
-
-case "$1" in
-  start)
-    start
-    ;;
-  start_foreground)
-    start_foreground
-    ;;
-  stop)
-    stop
-    ;;
-  reload)
-    reload
-    ;;
-  *)
-    echo "Usage: RAILS_ENV=your_env $0 {start|stop|reload}"
-    ;;
+    *)
+        echo "Unkown web server used by USE_WEB_SERVER: $USE_WEB_SERVER."
+        exit 1
+        ;;
 esac

bin/web_unicorn

@@ -0,0 +1,58 @@
+#!/bin/sh
+
+cd $(dirname $0)/..
+app_root=$(pwd)
+
+unicorn_pidfile="$app_root/tmp/pids/unicorn.pid"
+unicorn_config="$app_root/config/unicorn.rb"
+unicorn_cmd="bundle exec unicorn_rails -c $unicorn_config -E $RAILS_ENV"
+
+get_unicorn_pid()
+{
+  local pid=$(cat $unicorn_pidfile)
+  if [ -z "$pid" ] ; then
+    echo "Could not find a PID in $unicorn_pidfile"
+    exit 1
+  fi
+  unicorn_pid=$pid
+}
+
+start()
+{
+  exec $unicorn_cmd -D
+}
+
+start_foreground()
+{
+  exec $unicorn_cmd
+}
+
+stop()
+{
+  get_unicorn_pid
+  kill -QUIT $unicorn_pid
+}
+
+reload()
+{
+  get_unicorn_pid
+  kill -USR2 $unicorn_pid
+}
+
+case "$1" in
+  start)
+    start
+    ;;
+  start_foreground)
+    start_foreground
+    ;;
+  stop)
+    stop
+    ;;
+  reload)
+    reload
+    ;;
+  *)
+    echo "Usage: RAILS_ENV=your_env $0 {start|stop|reload}"
+    ;;
+esac

config/initializers/rack_timeout.rb

@@ -14,8 +14,8 @@ if defined?(::Puma) && !Rails.env.test?
 
   Gitlab::Application.configure do |config|
     config.middleware.insert_before(Rack::Runtime, Rack::Timeout,
-                                    service_timeout: 60,
-                                    wait_timeout: 90)
+                                    service_timeout: ENV.fetch('GITLAB_RAILS_RACK_TIMEOUT', 60).to_i,
+                                    wait_timeout: ENV.fetch('GITLAB_RAILS_WAIT_TIMEOUT', 90).to_i)
   end
 
   observer = Gitlab::Cluster::RackTimeoutObserver.new