Error in launcing app server in Heroku (And how to solve)

Environments

Heroku
Memcachier
Rails 5 API Mode
MySQL ClearDB

Error

2017-04-25T08:46:54.321621+00:00 app[web.1]: W, [2017-04-25T08:46:54.321561 #4]  WARN -- : localhost:11211 failed (count: 0) Errno::ECONNREFUSED: Connection refused - connect(2) for "localhost" port 11211

source code (before resolve the problem)

configuration file

config/environments/production.rb

  config.cache_store = :dalli_store,
    nil,
    { 
      :username => ENV["MEMCACHIER_USERNAME"],
      :password => ENV["MEMCACHIER_PASSWORD"],
      :failover => true,
      :socket_timeout => 1.5,
      :socket_failure_delay => 0.2,
      :down_retry_delay => 60,
      :expires_in => 7.day,
      :compress => true,
      :namespace => 'Planna-prod',
    }

note: According to GitHub - petergoldstein/dalli: High performance memcached client for Ruby

If your servers are specified in ENV"MEMCACHE_SERVERS", simply provide nil for the servers:

Or simply write configuration according to a Heroku document.

config/environments/production.rb

  config.cache_store = :dalli_store,
    (ENV["MEMCACHIER_SERVERS"] || "").split(","),
    { 
      :username => ENV["MEMCACHIER_USERNAME"],
      :password => ENV["MEMCACHIER_PASSWORD"],
      :failover => true,
      :socket_timeout => 1.5,
      :socket_failure_delay => 0.2,
      :down_retry_delay => 60,
      :expires_in => 7.day,
      :compress => true,
      :namespace => 'Planna-prod',

and, in config/application.rb is a middleware configuration as

config.middleware.use ActionDispatch::Session::MemCacheStore, expires_after: 7.day

and, config/initializers/session_store.rb is

Rails.application.config.session_store :mem_cache_store

environmental variables

Enviromental variables are set as below,
* MEMCACHE_PASSWORD
* MEMCACHE_USERNAME
* MEMCACHE_SERVERS
* MEMCACHIER_PASSWORD
* MEMCACHIER_USERNAME
* MEMCACHIER_SERVERS

the first try

Modify config/initializers/session_store.rb from

Rails.application.config.session_store :mem_cache_store

To

Rails.application.config.session_store :dalli_store

the second try

Modify config/application.rb from

config.middleware.use ActionDispatch::Session::MemCacheStore, expires_after: 7.day

To

require 'action_dispatch/middleware/session/dalli_store'
config.middleware.use ActionDispatch::Session::DalliStore, expires_after: 7.day

and then I encountered the same problem as mentioned in this issue: https://github.com/petergoldstein/dalli/issues/613

so I tried to fix up the code the instruction In the issue 613.

Update the value of config.cache_store in your environment configuration to be :dalli_store
Set the config.session_store values to ActionDispatch::Session::CacheStore with whatever options you'd like

Then the problem in heroku (the output is below)

2017-04-25T10:00:38.564394+00:00 heroku[web.1]: Process exited with status 0
2017-04-25T10:00:39.945440+00:00 heroku[web.1]: Starting process with command `bin/rails server -p 29870 -e production`
2017-04-25T10:00:42.430045+00:00 app[web.1]: /app/vendor/bundle/ruby/2.4.0/gems/activesupport-5.0.1/lib/active_support/xml_mini.rb:51: warning: constant ::Fixnum is deprecated
2017-04-25T10:00:42.430073+00:00 app[web.1]: /app/vendor/bundle/ruby/2.4.0/gems/activesupport-5.0.1/lib/active_support/xml_mini.rb:52: warning: constant ::Bignum is deprecated
2017-04-25T10:00:43.478293+00:00 app[web.1]: => Booting Puma
2017-04-25T10:00:43.478322+00:00 app[web.1]: => Rails 5.0.1 application starting in production on http://0.0.0.0:29870
2017-04-25T10:00:43.478323+00:00 app[web.1]: => Run `rails server -h` for more startup options