Ruby on rails 4 当终端中的相同start命令工作时，无法在debian上使用systemd运行puma（fe_sendauth:未提供密码错误）

我尝试用systemd在RubyonRails网站上管理Puma服务器。Puma无法启动，出现以下错误：PG:：ConnectionBad:fe_sendauth:未提供密码。当我在终端中使用与systemd中相同的启动命令启动Puma时，它会正确运行。请帮忙

我在Debian 9.12上使用RoR 4.2.11.1和postgresql 11.2，后者在VirtualBox 6.0上运行

网站文件结构：

/mytarifs/current - symlink to last release
/mytarifs/releases - relseas
/mytarifs/shared - shared files like database connections

我通过以下命令成功启动终端中的Puma：

        root@mt-staging-1:/mytarifs/current# bundle exec puma -C config/puma.production.rb

数据库URL环境变量：

        DATABASE_URL=postgresql://login_name:password@localhost:5432/db_tarif

通过这个数据库url，我可以用psql连接到我的数据库

错误日志：

        Mar 07 02:20:39 mt-staging-1 systemd[1]: Started puma for mytarifs (production).
        Mar 07 02:20:40 mt-staging-1 puma[12237]: [12237] Puma starting in cluster mode...
        Mar 07 02:20:40 mt-staging-1 puma[12237]: [12237] * Version 4.3.3 (ruby 2.3.8-p459), codename: Mysterious Traveller
        Mar 07 02:20:40 mt-staging-1 puma[12237]: [12237] * Min threads: 0, max threads: 5  
        Mar 07 02:20:40 mt-staging-1 puma[12237]: [12237] * Environment: production
        Mar 07 02:20:40 mt-staging-1 puma[12237]: [12237] * Process workers: 1
        Mar 07 02:20:40 mt-staging-1 puma[12237]: [12237] * Preloading application
        Mar 07 02:20:47 mt-staging-1 puma[12237]: The PGconn, PGresult, and PGError constants are deprecated, and will be
        Mar 07 02:20:47 mt-staging-1 puma[12237]: removed as of version 1.0.
        Mar 07 02:20:47 mt-staging-1 puma[12237]: You should use PG::Connection, PG::Result, and PG::Error instead, respectively.
        Mar 07 02:20:47 mt-staging-1 puma[12237]: Called from /mytarifs/releases/20200306184828/vendor/bundle/ruby/2.3.0/gems/activesupport-4.2.11.1/lib/active_support/dependencies.rb:240:in `load_dependency'

/mytarifs/current/config/puma.production.rb

threads Integer(ENV['MIN_THREADS']  || 0), Integer(ENV['MAX_THREADS'] || 5) 

        workers Integer(ENV['PUMA_WORKERS'] || 1) 
        preload_app! 

        bind 'unix:///mytarifs/shared/tmp/sockets/puma.sock'
        pidfile '/mytarifs/shared/tmp/pids/puma.production.pid'
        state_path '/mytarifs/shared/tmp/pids/puma.state'

        rackup DefaultRackup 
        environment ENV['RACK_ENV'] || 'production' 

        on_worker_boot do 
          ActiveSupport.on_load(:active_record) do 
            ActiveRecord::Base.establish_connection
          end 
        end 

/mytarifs/current/config/database.yml

        default: &default
          adapter: postgresql
          encoding: unicode
          pool: 125
          username: <%= ENV["PG_USERNAME"] %>
          password: <%= ENV["PG_PASSWORD"] %>
          host: localhost
          template: template0
          reconnect: true

        production:
          <<: *default
          url: <%= ENV["DATABASE_URL"] %>

---

好的，我找到了出错的原因。这是因为当systemd执行时，环境变量不可用（等于“”）。 我不知道如何从内存中获取环境变量，但systemd可以使用指令EnvironmentFile=/absolute/path/to/environment/file从文件中获取环境变量

        [Unit]
        Description=puma for mytarifs (production)
        After=network.target

        [Service]
        Type=simple
        Environment=RAILS_ENV=production
        Environment=PUMA_DEBUG=1
        WorkingDirectory=/mytarifs/current
        ExecStart=/root/.rbenv/shims/bundle exec puma -e production -C config/puma.production.rb
        ExecReload=/bin/kill -TSTP $MAINPID
        ExecStop=/bin/kill -TERM $MAINPID
        User=root
        Group=root

        RestartSec=1
        Restart=on-failure

        SyslogIdentifier=puma

        [Install]
         WantedBy=multi-user.target