cloud9でのrails serverの開き方と対処

前提・実現したいこと

ここ数日rails の環境構築に悩まされており、色々調べてCloud9に至ったのですが、結局そこでもサーバーを起動することが出来ませんでした。sqlite3の更新やら何やらを調べられる範囲で調べて試したのですが、自前の構築でもcloud9でも駄目でした。初心者の自分ではもう詰みの状態なので詳しい方にお力添えをお願いしたいです。

発生している問題・エラーメッセージ

開いたwebページ（Gem::LoadError）↓↓

Specified 'sqlite3' for database adapter, but the gem is not loaded. Add gem 'sqlite3' to your Gemfile (and ensure its version is at the minimum required by ActiveRecord).

xtracted source (around line #176):
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        require path_to_adapter
      rescue Gem::LoadError => e
        raise Gem::LoadError, "Specified '#{spec[:adapter]}' for database adapter, but the gem is not loaded. Add `gem '#{e.name}'` to your Gemfile (and ensure its version is at the minimum required by ActiveRecord)."
      rescue LoadError => e
        raise LoadError, "Could not load '#{path_to_adapter}'. Make sure that the adapter in config/database.yml is valid. If you use an adapter other than 'mysql2', 'postgresql' or 'sqlite3' add the necessary adapter gem to the Gemfile.", e.backtrace
      end

Rails.root: /home/ec2-user/environment/s

Application Trace | Framework Trace | Full Trace
activerecord (5.0.7.2) lib/active_record/connection_adapters/connection_specification.rb:176:in rescue in spec' activerecord (5.0.7.2) lib/active_record/connection_adapters/connection_specification.rb:173:in spec'
activerecord (5.0.7.2) lib/active_record/connection_handling.rb:53:in establish_connection' activerecord (5.0.7.2) lib/active_record/railtie.rb:125:in block (2 levels) in class:Railtie'
activesupport (5.0.7.2) lib/active_support/lazy_load_hooks.rb:69:in instance_eval' activesupport (5.0.7.2) lib/active_support/lazy_load_hooks.rb:69:in block in execute_hook'
activesupport (5.0.7.2) lib/active_support/lazy_load_hooks.rb:60:in with_execution_control' activesupport (5.0.7.2) lib/active_support/lazy_load_hooks.rb:65:in execute_hook'
activesupport (5.0.7.2) lib/active_support/lazy_load_hooks.rb:50:in block in run_load_hooks' activesupport (5.0.7.2) lib/active_support/lazy_load_hooks.rb:49:in each'
activesupport (5.0.7.2) lib/active_support/lazy_load_hooks.rb:49:in run_load_hooks' activerecord (5.0.7.2) lib/active_record/base.rb:324:in module:ActiveRecord'
activerecord (5.0.7.2) lib/active_record/base.rb:24:in <top (required)>' activesupport (5.0.7.2) lib/active_support/dependencies.rb:293:in require'
activesupport (5.0.7.2) lib/active_support/dependencies.rb:293:in block in require' activesupport (5.0.7.2) lib/active_support/dependencies.rb:259:in load_dependency'
activesupport (5.0.7.2) lib/active_support/dependencies.rb:293:in require' activerecord (5.0.7.2) lib/active_record/migration.rb:559:in connection'
activerecord (5.0.7.2) lib/active_record/migration.rb:546:in call' actionpack (5.0.7.2) lib/action_dispatch/middleware/callbacks.rb:38:in block in call'
activesupport (5.0.7.2) lib/active_support/callbacks.rb:97:in __run_callbacks__' activesupport (5.0.7.2) lib/active_support/callbacks.rb:750:in _run_call_callbacks'
activesupport (5.0.7.2) lib/active_support/callbacks.rb:90:in run_callbacks' actionpack (5.0.7.2) lib/action_dispatch/middleware/callbacks.rb:36:in call'
actionpack (5.0.7.2) lib/action_dispatch/middleware/executor.rb:12:in call' actionpack (5.0.7.2) lib/action_dispatch/middleware/remote_ip.rb:79:in call'
actionpack (5.0.7.2) lib/action_dispatch/middleware/debug_exceptions.rb:49:in call' web-console (3.7.0) lib/web_console/middleware.rb:135:in call_app'
web-console (3.7.0) lib/web_console/middleware.rb:22:in block in call' web-console (3.7.0) lib/web_console/middleware.rb:20:in catch'
web-console (3.7.0) lib/web_console/middleware.rb:20:in call' actionpack (5.0.7.2) lib/action_dispatch/middleware/show_exceptions.rb:31:in call'
railties (5.0.7.2) lib/rails/rack/logger.rb:36:in call_app' railties (5.0.7.2) lib/rails/rack/logger.rb:24:in block in call'
activesupport (5.0.7.2) lib/active_support/tagged_logging.rb:69:in block in tagged' activesupport (5.0.7.2) lib/active_support/tagged_logging.rb:26:in tagged'
activesupport (5.0.7.2) lib/active_support/tagged_logging.rb:69:in tagged' railties (5.0.7.2) lib/rails/rack/logger.rb:24:in call'
sprockets-rails (3.2.1) lib/sprockets/rails/quiet_assets.rb:13:in call' actionpack (5.0.7.2) lib/action_dispatch/middleware/request_id.rb:24:in call'
rack (2.0.7) lib/rack/method_override.rb:22:in call' rack (2.0.7) lib/rack/runtime.rb:22:in call'
activesupport (5.0.7.2) lib/active_support/cache/strategy/local_cache_middleware.rb:28:in call' actionpack (5.0.7.2) lib/action_dispatch/middleware/executor.rb:12:in call'
actionpack (5.0.7.2) lib/action_dispatch/middleware/static.rb:136:in call' rack (2.0.7) lib/rack/sendfile.rb:111:in call'
railties (5.0.7.2) lib/rails/engine.rb:522:in call' puma (3.12.1) lib/puma/configuration.rb:227:in call'
puma (3.12.1) lib/puma/server.rb:660:in handle_request' puma (3.12.1) lib/puma/server.rb:474:in process_client'
puma (3.12.1) lib/puma/server.rb:334:in block in run' puma (3.12.1) lib/puma/thread_pool.rb:135:in block in spawn_thread'
This error occurred while loading the following files:
active_record/base
Request

該当のソースコード

=> Booting Puma
=> Rails 5.0.7.2 application starting in development on http://localhost:8080
=> Run rails server -h for more startup options
Puma starting in single mode...

Version 3.12.1 (ruby 2.6.3-p62), codename: Llamas in Pajamas
Min threads: 5, max threads: 5
Environment: development
Listening on tcp://localhost:8080

Use Ctrl-C to stop