[英]How can a runit' service restart return instantly?
I have a runit
service I use to run a rails
app using unicorn
. 我有一个
runit
服务,用于使用unicorn
运行rails
应用程序。
Its restart command uses a signal (USR2) to handle a zero-downtime restart. 其重启命令使用信号(USR2)处理零停机时间重启。 Basically, it waits until the new process is ready before the old ones die.
基本上,它会等到新流程准备就绪,然后旧流程才能消失。
This causes a very long (40 seconds) restart time, in which service myservice restart
doesn't return until the end. 这将导致很长的重启时间(40秒),其中
service myservice restart
直到结束才返回。
While I can give runit a longer timeout (which I already do), I want to make this restart a fire-and-forget kind of action so it'll return instantly (or after the USR2 signal was fired, but without waiting for it to complete. 虽然我可以给Runit更长的超时时间(我已经这样做了),但我想让重启重新启动一次“忘了”的操作,以便它立即返回(或在发出USR2信号后立即返回,但无需等待)去完成。
The entire logic is taken from multiple blog posts about zero-downtime rails
deployments with unicorn
restarts: 整个逻辑取材自多篇有关采用
unicorn
重启的零停机rails
部署的博客文章:
This is the runit
script (generated by chef): 这是
runit
脚本(由厨师生成):
#!/bin/bash
#
# This file is managed by Chef, using the <%= node.name %> cookbook.
# Editing this file by hand is highly discouraged!
#
exec 2>&1
#
# Since unicorn creates a new pid on restart/reload, it needs a little extra
# love to manage with runit. Instead of managing unicorn directly, we simply
# trap signal calls to the service and redirect them to unicorn directly.
#
RUNIT_PID=$$
APPLICATION_NAME=<%= @options[:application_name] %>
APPLICATION_PATH=<%= File.join(@options[:path], 'current') %>
BUNDLE_CMD="<%= @options[:bundle_command] ? "#{@options[:bundle_command]} exec" : '' %>"
UNICORN_CMD=<%= @options[:unicorn_command] ? @options[:unicorn_command] : 'unicorn' %>
UNICORN_CONF=<%= @options[:unicorn_config_path] ? @options[:unicorn_config_path] : File.join(@options[:path], 'current', 'config', 'unicorn.rb') %>
RAILS_ENV=<%= @options[:rails_env] %>
CUR_PID_FILE=<%= @options['pid'] ? @options['pid'] : File.join(@options[:path], 'current', 'shared', 'pids', "#{@options[:application_name]}.pid") %>
ENV_PATH=<%= @options[:env_dir] %>
OLD_PID_FILE=$CUR_PID_FILE.oldbin
echo "Runit service restarted (PID: $RUNIT_PID)"
function is_unicorn_alive {
set +e
if [ -n $1 ] && kill -0 $1 >/dev/null 2>&1; then
echo "yes"
fi
set -e
}
if [ -e $OLD_PID_FILE ]; then
OLD_PID=$(cat $OLD_PID_FILE)
echo "Old master detected (PID: $OLD_PID), waiting for it to quit"
while [ -n "$(is_unicorn_alive $OLD_PID)" ]; do
sleep 5
done
fi
if [ -e $CUR_PID_FILE ]; then
CUR_PID=$(cat $CUR_PID_FILE)
if [ -n "$(is_unicorn_alive $CUR_PID)" ]; then
echo "Detected running Unicorn instance (PID: $CUR_PID)"
RUNNING=true
fi
fi
function start {
unset ACTION
if [ $RUNNING ]; then
restart
else
echo 'Starting new unicorn instance'
cd $APPLICATION_PATH
exec chpst -e $ENV_PATH $BUNDLE_CMD $UNICORN_CMD -c $UNICORN_CONF -E $RAILS_ENV
sleep 3
CUR_PID=$(cat $CUR_PID_FILE)
fi
}
function stop {
unset ACTION
echo 'Initializing graceful shutdown'
kill -QUIT $CUR_PID
while [ -n "$(is_unicorn_alive $CUR_PID)" ]; do
echo '.'
sleep 2
done
echo 'Unicorn stopped, exiting Runit process'
kill -9 $RUNIT_PID
}
function restart {
unset ACTION
echo "Restart request captured, swapping old master (PID: $CUR_PID) for new master with USR2"
kill -USR2 $CUR_PID
sleep 2
echo 'Restarting Runit service to capture new master PID'
exit
}
function alarm {
unset ACTION
echo 'Unicorn process interrupted'
}
trap 'ACTION=stop' STOP TERM KILL
trap 'ACTION=restart' QUIT USR2 INT
trap 'ACTION=alarm' ALRM
[ $RUNNING ] || ACTION=start
if [ $ACTION ]; then
echo "Performing \"$ACTION\" action and going into sleep mode until new signal captured"
elif [ $RUNNING ]; then
echo "Going into sleep mode until new signal captured"
fi
if [ $ACTION ] || [ $RUNNING ]; then
while true; do
[ "$ACTION" == 'start' ] && start
[ "$ACTION" == 'stop' ] && stop
[ "$ACTION" == 'restart' ] && restart
[ "$ACTION" == 'alarm' ] && alarm
sleep 2
done
fi
This is a super weird way to use Runit, move your reload logic to the control/h
script and use sv hup
(or since it doesn't seem to be anything more than sending USR2 sv 2
). 这是使用Runit,将重载逻辑移至
control/h
脚本并使用sv hup
一种非常奇怪的方法(或者因为它似乎只不过是发送USR2 sv 2
而已)。 The main run script shouldn't be involved. 主运行脚本不应参与。
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