Capistrano/nginx/Unicorn: Website is randomly up and down - ruby-on-rails

Question

I am using Capistrano to deploy my code to a DigitalOcean server. I added to the deploy.rb file the block for restarting Unicorn after every deploy, but since then I have noticed that when I got to the browser and start refreshing the website, sometimes I get refreshed the website and sometimes only a blank (white) page. It's a total random.
deploy.rb:
# config valid only for current version of Capistrano
lock "3.8.1"
set :application, "project"
set :repo_url, "git#bitbucket.org:username/project.git"
set :branch, "master"
set :tmp_dir, '/home/deployer/tmp'
set :deploy_to, "/home/deployer/apps/project"
set :keep_releases, 5
set(:executable_config_files, %w(
unicorn_init.sh
))
# files which need to be symlinked to other parts of the
# filesystem. For example nginx virtualhosts, log rotation
# init scripts etc.
set(:symlinks, [
{
source: "nginx.conf",
link: "/etc/nginx/sites-enabled/default"
},
{
source: "unicorn_init.sh",
link: "/etc/init.d/unicorn_#{fetch(:application)}"
},
{
source: "log_rotation",
link: "/etc/logrotate.d/#{fetch(:application)}"
},
{
source: "monit",
link: "/etc/monit/conf.d/#{fetch(:application)}.conf"
}
])
namespace :deploy do
desc 'Restart application'
task :restart_unicorn do
on roles(:app) do
execute '/home/deployer/apps/project/current/config/unicorn_init.sh restart'
end
end
after :publishing, :restart_unicorn
desc "Make sure local git is in sync with remote."
task :check_revision do
on roles(:web) do
unless `git rev-parse HEAD` == `git rev-parse origin/master`
puts "WARNING: HEAD is not the same as origin/master"
puts "Run `git push` to sync changes."
exit
end
end
end
before "deploy", "deploy:check_revision"
end
unicorn_init.sh:
set -e
TIMEOUT=${TIMEOUT-60}
APP_ROOT=/home/deployer/apps/project/current
#PID=$APP_ROOT/tmp/pids/unicorn.pid
PID=/home/deployer/apps/project/shared/pids/unicorn.pid
#CMD="cd $APP_ROOT; bundle exec unicorn -D -c $APP_ROOT/config/unicorn.rb -E production"
CMD="cd $APP_ROOT; bundle exec unicorn -D -c $APP_ROOT/config/unicorn/production.rb -E production"
AS_USER=deployer
set -u
OLD_PIN="$PID.oldbin"
sig () {
test -s "$PID" && kill -$1 `cat $PID`
}
oldsig () {
test -s $OLD_PIN && kill -$1 `cat $OLD_PIN`
}
run () {
if [ "$(id -un)" = "$AS_USER" ]; then
eval $1
else
su -c "$1" - $AS_USER
fi
}
case "$1" in
start)
sig 0 && echo >&2 "Already running" && exit 0
run "$CMD"
;;
stop)
sig QUIT && exit 0
echo >&2 "Not running"
;;
force-stop)
sig TERM && exit 0
echo >&2 "Not running"
;;
restart|reload)
#sig HUP && echo reloaded OK && exit 0
sig USR2 && echo reloaded OK && exit 0
echo >&2 "Couldn't reload, starting '$CMD' instead"
run "$CMD"
;;
upgrade)
if sig USR2 && sleep 2 && sig 0 && oldsig QUIT
then
n=$TIMEOUT
while test -s $OLD_PIN && test $n -ge 0
do
printf '.' && sleep 1 && n=$(( $n - 1 ))
done
echo
if test $n -lt 0 && test -s $OLD_PIN
then
echo >&2 "$OLD_PIN still exists after $TIMEOUT seconds"
exit 1
fi
exit 0
fi
echo >&2 "Couldn't upgrade, starting '$CMD' instead"
run "$CMD"
;;
reopen-logs)
sig USR1
;;
*)
echo >&2 "Usage: $0 <start|stop|restart|upgrade|force-stop|reopen-logs>"
exit 1
;;
esac
What I have change in this file - this line:
sig HUP && echo reloaded OK && exit 0
for this one:
sig USR2 && echo reloaded OK && exit 0
I am trying to look to the unicorn log file, but there is nothing relevant to this issue. production.log - same, nothing relevant. When I am looking for an nginx log file, I found on here: /var/log/nginx/error.log, but the fiel is empty (size 0).
Any advice what to do with this issue/what is wrong or where even to start?
EDIT: in the /home/deployer/apps/rentalhistory/shared/pids directory, there are these two files:
unicorn.pid.oldbin and unicorn.pid - should not be one of the removed?
Thanks!

Answer 1

What was the problem in my case - when was reloaded Unicorn, the new unicorn PID was generated (unicorn.pid) - that's correct, but the old one (unicorn.pid.oldbin) was still staying in the system. And this was apparently causing the random downs of the whole website.
FIX: I checked my Unicorn config file (config/production.rb) and this line was wrong - the path:
old_pid = "#{root}/shared/pids/unicorn.pid.oldbin"
The shared directory is on the same level as current, not inside of it.
After this change, the new unicorn PID is created and the old one is properly removed.