Use semantic JSON logging in production#284
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vangberg wants to merge 1 commit into
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vangberg
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Jun 18, 2026
| # config.logger = ActiveSupport::TaggedLogging.new(Syslog::Logger.new 'app-name') | ||
| config.rails_semantic_logger.format = :json | ||
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| if ENV['RAILS_LOG_TO_STDOUT'].present? |
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This does not seem to be in use anywhere. We could remove the whole block I think.
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Hi @vangberg |
lmrodriguezr
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Jun 25, 2026
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Let's discuss this in-person maybe.
Structured JSON log with the Semantic Logger gem.
This will change the format of the messages logged to
production.logto JSON, e.g.:{"host":"Mac","application":"seqcode-registry","environment":"development","timestamp":"2026-06-18T08:53:26.417321Z","level":"debug","level_index":1,"pid":23874,"thread":"puma srv tp 005","duration_ms":0.4759998992085457,"duration":"0.476ms","named_tags":{"request_id":"aca6012d-4fc0-4fa4-9ef8-086377cb11bf"},"name":"ActiveRecord","payload":{"sql":"SELECT COUNT(*) FROM \"names\" WHERE \"names\".\"status\" = $1","binds":{"status":15},"allocations":254,"cached":null}} {"host":"Mac","application":"seqcode-registry","environment":"development","timestamp":"2026-06-18T08:52:38.871463Z","level":"debug","level_index":1,"pid":23874,"thread":"puma srv tp 003","named_tags":{"request_id":"54192b6f-d025-4fed-8f32-2ba51396a7b6"},"name":"Rack","message":"Started","payload":{"method":"GET","path":"/api/v1/names/1.json","ip":"127.0.0.1"}} {"host":"Mac","application":"seqcode-registry","environment":"development","timestamp":"2026-06-18T08:52:38.878342Z","level":"fatal","level_index":5,"pid":23874,"thread":"puma srv tp 003","file":"/Users/harryvangberg/.asdf/installs/ruby/3.3.9/lib/ruby/gems/3.3.0/gems/concurrent-ruby-1.3.6/lib/concurrent-ruby/concurrent/atomic/thread_local_var.rb","line":93,"named_tags":{"request_id":"54192b6f-d025-4fed-8f32-2ba51396a7b6"},"name":"Rails","exception":{"name":"ActionController::RoutingError","message":"No route matches [GET] \"/api/v1/names/1.json\"","stack_trace":["/Users/harryvangberg/.asdf/installs/ruby/3.3.9/lib/ruby/gems/3.3.0/gems/actionpack-6.1.7.10/lib/action_dispatch/middleware/debug_exceptions.rb:33:in `call'","/Users/harryvangberg/.asdf/installs/ruby/3.3.9/lib/ruby/gems/3.3.0/gems/web-console-4.2.1/lib/web_console/middleware.rb:132:in `call_app'","/Users/harryvangberg/.asdf/installs/ruby/3.3.9/lib/ruby/gems/3.3.0/gems/web-console-4.2.1/lib/web_console/middleware.rb:28:in `block in call'","/Users/harryvangberg/.asdf/installs/ruby/3.3.9/lib/ruby/gems/3.3.0/gems/web-console-4.2.1/lib/web_console/middleware.rb:17:in `catch'","/Users/harryvangberg/.asdf/installs/ruby/3.3.9/lib/ruby/gems/3.3.0/gems/web-console-4.2.1/lib/web_console/middleware.rb:17:in `call'","/Users/harryvangberg/.asdf/installs/ruby/3.3.9/lib/ruby/gems/3.3.0/gems/actionpack-6.1.7.10/lib/action_dispatch/middleware/show_exceptions.rb:33:in `call'","/Users/harryvangberg/.asdf/installs/ruby/3.3.9/lib/ruby/gems/3.3.0/gems/rails_semantic_logger-4.20.0/lib/rails_semantic_logger/rack/logger.rb:53:in `call_app'","/Users/harryvangberg/.asdf/installs/ruby/3.3.9/lib/ruby/gems/3.3.0/gems/rails_semantic_logger-4.20.0/lib/rails_semantic_logger/rack/logger.rb:26:in `block in call'","/Users/harryvangberg/.asdf/installs/ruby/3.3.9/lib/ruby/gems/3.3.0/gems/semantic_logger-4.18.0/lib/semantic_logger/base.rb:202:in `block in tagged'","/Users/harryvangberg/.asdf/installs/ruby/3.3.9/lib/ruby/gems/3.3.0/gems/semantic_logger-4.18.0/lib/semantic_logger/semantic_logger.rb:395:in `named_tagged'","/Users/harryvangberg/.asdf/installs/ruby/3.3.9/lib/ruby/gems/3.3.0/gems/semantic_logger-4.18.0/lib/semantic_logger/base.rb:209:in `tagged'","/Users/harryvangberg/.asdf/installs/ruby/3.3.9/lib/ruby/gems/3.3.0/gems/rails_semantic_logger-4.20.0/lib/rails_semantic_logger/rack/logger.rb:26:in `call'","/Users/harryvangberg/.asdf/installs/ruby/3.3.9/lib/ruby/gems/3.3.0/gems/actionpack-6.1.7.10/lib/action_dispatch/middleware/remote_ip.rb:81:in `call'","/Users/harryvangberg/.asdf/installs/ruby/3.3.9/lib/ruby/gems/3.3.0/gems/actionpack-6.1.7.10/lib/action_dispatch/middleware/request_id.rb:26:in `call'","/Users/harryvangberg/.asdf/installs/ruby/3.3.9/lib/ruby/gems/3.3.0/gems/rack-2.2.23/lib/rack/method_override.rb:24:in `call'","/Users/harryvangberg/.asdf/installs/ruby/3.3.9/lib/ruby/gems/3.3.0/gems/rack-2.2.23/lib/rack/runtime.rb:22:in `call'","/Users/harryvangberg/.asdf/installs/ruby/3.3.9/lib/ruby/gems/3.3.0/gems/activesupport-6.1.7.10/lib/active_support/cache/strategy/local_cache_middleware.rb:29:in `call'","/Users/harryvangberg/.asdf/installs/ruby/3.3.9/lib/ruby/gems/3.3.0/gems/actionpack-6.1.7.10/lib/action_dispatch/middleware/executor.rb:14:in `call'","/Users/harryvangberg/.asdf/installs/ruby/3.3.9/lib/ruby/gems/3.3.0/gems/actionpack-6.1.7.10/lib/action_dispatch/middleware/static.rb:24:in `call'","/Users/harryvangberg/.asdf/installs/ruby/3.3.9/lib/ruby/gems/3.3.0/gems/rack-2.2.23/lib/rack/sendfile.rb:127:in `call'","/Users/harryvangberg/.asdf/installs/ruby/3.3.9/lib/ruby/gems/3.3.0/gems/actionpack-6.1.7.10/lib/action_dispatch/middleware/host_authorization.rb:148:in `call'","/Users/harryvangberg/.asdf/installs/ruby/3.3.9/lib/ruby/gems/3.3.0/gems/rack-cors-2.0.2/lib/rack/cors.rb:102:in `call'","/Users/harryvangberg/.asdf/installs/ruby/3.3.9/lib/ruby/gems/3.3.0/gems/webpacker-5.4.4/lib/webpacker/dev_server_proxy.rb:25:in `perform_request'","/Users/harryvangberg/.asdf/installs/ruby/3.3.9/lib/ruby/gems/3.3.0/gems/rack-proxy-0.7.7/lib/rack/proxy.rb:87:in `call'","/Users/harryvangberg/.asdf/installs/ruby/3.3.9/lib/ruby/gems/3.3.0/gems/railties-6.1.7.10/lib/rails/engine.rb:539:in `call'","/Users/harryvangberg/.asdf/installs/ruby/3.3.9/lib/ruby/gems/3.3.0/gems/puma-5.6.9/lib/puma/configuration.rb:252:in `call'","/Users/harryvangberg/.asdf/installs/ruby/3.3.9/lib/ruby/gems/3.3.0/gems/puma-5.6.9/lib/puma/request.rb:77:in `block in handle_request'","/Users/harryvangberg/.asdf/installs/ruby/3.3.9/lib/ruby/gems/3.3.0/gems/puma-5.6.9/lib/puma/thread_pool.rb:340:in `with_force_shutdown'","/Users/harryvangberg/.asdf/installs/ruby/3.3.9/lib/ruby/gems/3.3.0/gems/puma-5.6.9/lib/puma/request.rb:76:in `handle_request'","/Users/harryvangberg/.asdf/installs/ruby/3.3.9/lib/ruby/gems/3.3.0/gems/puma-5.6.9/lib/puma/server.rb:443:in `process_client'","/Users/harryvangberg/.asdf/installs/ruby/3.3.9/lib/ruby/gems/3.3.0/gems/puma-5.6.9/lib/puma/thread_pool.rb:147:in `block in spawn_thread'"]}}Stdout logs are still human-readable:
2026-06-18 10:53:26.365013 D [23874:puma srv tp 005] {request_id: aca6012d-4fc0-4fa4-9ef8-086377cb11bf} Rack -- Started -- {:method=>"GET", :path=>"/", :ip=>"127.0.0.1"} 2026-06-18 10:53:26.367874 D [23874:puma srv tp 005] {request_id: aca6012d-4fc0-4fa4-9ef8-086377cb11bf} ApplicationController -- Processing #main 2026-06-18 10:53:26.377091 D [23874:puma srv tp 005] {request_id: aca6012d-4fc0-4fa4-9ef8-086377cb11bf} (6.677ms) ActiveRecord -- {:sql=>"SELECT \"names\".\"nomenclatural_type_id\" FROM \"names\" WHERE \"names\".\"status\" IN ($1, $2, $3, $4) AND \"names\".\"redirect_id\" IS NULL AND \"names\".\"nomenclatural_type_type\" = $5", :binds=>{:status=>[0, 15, 20, 25], :nomenclatural_type_type=>"Genome"}, :allocations=>36, :cached=>nil}Grafana can parse JSON so it can be used to filter and group. In particular, this should make it possible to create a dashboard which groups and sums exceptions, which would be really helpful in tracking down/noticing errors.