Nginx and Unicorn not working due to unicorn.sock file error

Question

I am setting up VPS for the first time on upcloud. I am using unicorn 5.5.5 with Nginx. Rails 4.2.8 and ruby 2.4.2. My Nginx service runs fine. Doesn't show any error. Whenever I start unicorn service I get this error. I followed this tutorial.

https://medium.com/@manishyadavv/how-to-deploy-ruby-on-rails-apps-on-aws-ec2-7ce55bb955fa

F, [2020-06-16T12:44:20.611895 #12683] FATAL -- : error adding listener addr=/tmp/unicorn.sock
/usr/share/rvm/gems/ruby-2.4.2/gems/unicorn-5.5.5/lib/unicorn/socket_helper.rb:132:in `bind_listen': socket=/tmp/unicorn.sock specified but it is not a socket! (ArgumentError)
        from /usr/share/rvm/gems/ruby-2.4.2/gems/unicorn-5.5.5/lib/unicorn/http_server.rb:243:in `listen'
        from /usr/share/rvm/gems/ruby-2.4.2/gems/unicorn-5.5.5/lib/unicorn/http_server.rb:851:in `block in bind_new_listeners!'
        from /usr/share/rvm/gems/ruby-2.4.2/gems/unicorn-5.5.5/lib/unicorn/http_server.rb:851:in `each'
        from /usr/share/rvm/gems/ruby-2.4.2/gems/unicorn-5.5.5/lib/unicorn/http_server.rb:851:in `bind_new_listeners!'
        from /usr/share/rvm/gems/ruby-2.4.2/gems/unicorn-5.5.5/lib/unicorn/http_server.rb:142:in `start'
        from /usr/share/rvm/gems/ruby-2.4.2/gems/unicorn-5.5.5/bin/unicorn:128:in `<top (required)>'
        from /usr/share/rvm/gems/ruby-2.4.2/bin/unicorn:23:in `load'
        from /usr/share/rvm/gems/ruby-2.4.2/bin/unicorn:23:in `<main>'
        from /usr/share/rvm/gems/ruby-2.4.2/bin/ruby_executable_hooks:24:in `eval'
        from /usr/share/rvm/gems/ruby-2.4.2/bin/ruby_executable_hooks:24:in `<main>'

My unicorn.sock file is empty, I am sorry if this is a rookie mistake but I am stuck with this issue for 2 days now. Kindly help me out. Here is my unicorn_repo file in the etc/init.d directory

#!/bin/sh
### BEGIN INIT INFO
# Provides:          unicorn
# Required-Start:    $all
# Required-Stop:     $all
# Default-Start:     2 3 4 5
# Default-Stop:      0 1 6
# Short-Description: starts the unicorn app server
# Description:       starts unicorn using start-stop-daemon
### END INIT INFO
set -e
USAGE="Usage: $0 <start|stop|restart|upgrade|rotate|force-stop>"
# app settings
USER="root"
APP_NAME="soup"
APP_ROOT="/$USER/$APP_NAME"
ENV="production"
# environment settings
PATH="/home/$USER/.rbenv/shims:/home/$USER/.rbenv/bin:$PATH"
CMD="cd $APP_ROOT && bundle exec unicorn -c config/unicorn.rb -E $ENV -D"
PID="$APP_ROOT/shared/pids/unicorn.pid"
OLD_PID="$PID.oldbin"

here is my nginx/default file

upstream app {
    # Path to Unicorn SOCK file, as defined previously
    server unix:/tmp/unicorn.sock fail_timeout=0;
}
server {
    listen 0.0.0.0;
    server_name localhost;
    root root/soup/;
    try_files $uri/index.html $uri @app;
    location @app {
        proxy_pass http://app;
        proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
        proxy_set_header Host $http_host;
        proxy_redirect off;
    }
    error_page 500 502 503 504 /500.html;
    client_max_body_size 4G;
    keepalive_timeout 10;
}

Here is my unicorn.rb file.

# set path to application
app_dir = File.expand_path("../..", __FILE__)
shared_dir = "#{app_dir}/shared"
working_directory app_dir
# Set unicorn options
worker_processes 2
preload_app true
timeout 30
# Set up socket location
listen "/tmp/unicorn.sock", :backlog => 64
listen 3000, :tcp_nopush => true

# Logging
stderr_path "#{shared_dir}/log/unicorn.stderr.log"
stdout_path "#{shared_dir}/log/unicorn.stdout.log"
# Set master PID location
pid "#{shared_dir}/pids/unicorn.pid"
~
~
~
~

Answer 1

A socket is a special kind of file used for inter process communication. If you you run ls -la sockets have a leading s in the mode string.

Yours should look something like this:

srwxrwxrwx /tmp/unicorn.sock

If you have created /tmp/unicorn.sock as a file manually, delete it.

As a side note: The tutorial you are using is 3 years old and so your setup is outdated from the start.