add sentry config

.env.example

@@ -9,3 +9,5 @@ DATABASE_HOST=localhost
 DATABASE_PORT=5432
 
 REDIS_URL=
+
+SENTRY_DSN=

config/initializers/sentry.rb

@@ -0,0 +1,13 @@
+Sentry.init do |config|
+  config.dsn = ENV['SENTRY_DSN']
+  config.breadcrumbs_logger = [:active_support_logger]
+
+  # Set tracesSampleRate to 1.0 to capture 100%
+  # of transactions for performance monitoring.
+  # We recommend adjusting this value in production
+  config.traces_sample_rate = 1.0
+  # or
+  config.traces_sampler = lambda do |context|
+    true
+  end
+end