[ruby-on-rails] Rails: Address already in use - bind(2) (Errno::EADDRINUSE)

I am trying to deploy Rails app with the Puma web server. When trying to start Puma server with a config file bundle exec puma -C config/puma.rb I get an error that the address is already in use.

Does someone know how to fix this?

bundle exec puma -C config/puma.rb
[23699] Puma starting in cluster mode...
[23699] * Version 2.11.3 (ruby 2.0.0-p353), codename: Intrepid Squirrel
[23699] * Min threads: 5, max threads: 5
[23699] * Environment: development
[23699] * Process workers: 2
[23699] * Preloading application
Jdbc-MySQL is only for use with JRuby
[23699] * Listening on tcp://0.0.0.0:3000
/.rvm/gems/ruby-2.0.0-p353/gems/puma-2.11.3/lib/puma/binder.rb:210:in `initialize': Address already in use - bind(2) (Errno::EADDRINUSE)
    from /.rvm/gems/ruby-2.0.0-p353/gems/puma-2.11.3/lib/puma/binder.rb:210:in `new'
    from /Users/lexi87/.rvm/gems/ruby-2.0.0-p353/gems/puma-2.11.3/lib/puma/binder.rb:210:in `add_tcp_listener'
    from /.rvm/gems/ruby-2.0.0-p353/gems/puma-2.11.3/lib/puma/binder.rb:96:in `block in parse'
    from /.rvm/gems/ruby-2.0.0-p353/gems/puma-2.11.3/lib/puma/binder.rb:82:in `each'
    from /.rvm/gems/ruby-2.0.0-p353/gems/puma-2.11.3/lib/puma/binder.rb:82:in `parse'
    from /.rvm/gems/ruby-2.0.0-p353/gems/puma-2.11.3/lib/puma/runner.rb:119:in `load_and_bind'
    from /.rvm/gems/ruby-2.0.0-p353/gems/puma-2.11.3/lib/puma/cluster.rb:302:in `run'
    from /.rvm/gems/ruby-2.0.0-p353/gems/puma-2.11.3/lib/puma/cli.rb:216:in `run'
    from /rvm/gems/ruby-2.0.0-p353/gems/puma-2.11.3/bin/puma:10:in `<top (required)>'
    from /.rvm/gems/ruby-2.0.0-p353/bin/puma:23:in `load'
    from /.rvm/gems/ruby-2.0.0-p353/bin/puma:23:in `<main>'
    from /.rvm/gems/ruby-2.0.0-p353/bin/ruby_executable_hooks:15:in `eval'
    from /.rvm/gems/ruby-2.0.0-p353/bin/ruby_executable_hooks:15:in `<main>'

It might be old but in my case, it was because of docker. Hope it will help others.

You can find and kill the running processes: ps aux | grep puma Then you can kill it with kill PID

you can also try this trick:

ps aux | grep puma

sample output:

myname           77921   0.0  0.0  2433828   1972 s000  R+   11:17AM   0:00.00 grep puma
myname           67661   0.0  2.3  2680504 191204 s002  S+   11:00AM   0:18.38 puma 3.11.2 (tcp://localhost:3000) [my_proj]

then:

kill -9 67661

If the above solutions don't work on ubuntu/linux then you can try this

sudo fuser -k -n tcp port

Run it several times to kill processes on your port of choosing. port could be 3000 for example. You would have killed all the processes if you see no output after running the command

Found the script below in this github issue. Works great for me.

#!/usr/bin/env ruby
port = ARGV.first || 3000
system("sudo echo kill-server-on #{port}")

pid = `sudo lsof -iTCP -sTCP:LISTEN -n -P | grep #{port} | awk '{ print $2 }' | head -n 1`.strip
puts "PID: #{pid}"
`kill -9 #{pid}` unless pid.empty?

You can either run it in irb or inside a ruby file.

For the latter, create server_killer.rb then run it with ruby server_killer.rb

To kill the puma process first run

    lsof -wni tcp:3000 

to show what is using port 3000. Then use the PID that comes with the result to run the kill process.

For example after running lsof -wni tcp:3000 you might get something like

    COMMAND  PID  USER   FD   TYPE DEVICE SIZE/OFF NODE NAME
    ruby    3366 dummy    8u  IPv4  16901      0t0  TCP 127.0.0.1:3000 (LISTEN)

Now run the following to kill the process. (where 3366 is the PID)

kill -9 3366

Should resolve the issue