Merge pull request #451 from epimorphics/issue/449-task-prometheus-me…

…trics-update

Task: Prometheus Metrics - Update

CHANGELOG.md

@@ -2,7 +2,24 @@
 
 ## 1.7.5 - 2024-09
 
-- (Dan) Updates Welsh translation to the official Welsh translation [GH-435](https://github.com/epimorphics/ukhpi/issues/435)
+- (Jon) Created a `local` makefile target to allow for local development without
+  asset compilation
+- (Jon) Updated the puma-stats to display in the footer while in development
+  [GH-449](https://github.com/epimorphics/ukhpi/issues/449)
+- (Jon) Updated the application exceptions controller to instrument the
+  `ActiveSupport::Notifications` for internal errors albeit this is not
+  currently in use in the application
+  [GH-449](https://github.com/epimorphics/ukhpi/issues/449)
+- (Jon) Updated `config/initializers/prometheus.rb` to include the `Middleware
+  instrumentation` fix for the 0 memory bug by notifying Action Dispatch
+  subscribers on Prometheus initialise
+  [GH-449](https://github.com/epimorphics/ukhpi/issues/449)
+- (Jon) Updated `config/puma.rb` to include metrics plugin and port information
+  for the metrics endpoint as environment variable, with default, to enable
+  running multiple sibling HMLR apps locally if needed without port conflicts
+  [GH-449](https://github.com/epimorphics/ukhpi/issues/449)
+- (Dan) Updates Welsh translation to the official Welsh translation
+  [GH-435](https://github.com/epimorphics/ukhpi/issues/435)
 - (Jon) Moved all mirrored configuration settings from individual environments
   into the application configuration to reduce the need to manage multiple
   sources of truth

Makefile

@@ -68,6 +68,14 @@ image: auth
 lint: assets
 	@./bin/bundle exec rubocop
 
+local:
+	@echo "Installing bundler packages ..."
+	@./bin/bundle install
+	@echo "Installing yarn packages ..."
+	@yarn install
+	@echo "Starting local server ..."
+	@./bin/rails server -p ${PORT}
+
 publish: image
 	@echo Publishing image: ${REPO}:${TAG} ...
 	@docker tag ${NAME}:${TAG} ${REPO}:${TAG} 2>&1

app/views/common/_footer.html.haml

@@ -29,8 +29,3 @@
         %p.u-muted--footer
           = t('common.footer.application_release')
           = Version::VERSION
-    - if Rails.env.development?
-      %pre
-        [puma stats:
-        = JSON.pretty_generate(JSON.parse(Puma.stats, symbolize_names: true))
-        , time: #{Time.now}]

app/views/common/_puma_stats.html.haml

@@ -0,0 +1,5 @@
+
+%div
+  %pre
+    %code
+      = "[#{JSON.pretty_generate(puma_stats: JSON.parse(Puma.stats), time: Time.now)}]"

app/views/layouts/application.html.haml

@@ -40,3 +40,4 @@
 
 
     = render partial: 'common/footer'
+    = render partial: 'common/puma_stats' if Rails.env.development?

config/initializers/prometheus.rb

@@ -48,3 +48,7 @@
   docstring: 'Histogram of response times for API requests',
   buckets: Prometheus::Client::Histogram.exponential_buckets(start: 0.005, count: 16)
 )
+
+# Middleware instrumentation
+  # This fixes the 0 memory bug by notifying Action Dispatch subscribers on Prometheus initialise
+  ActiveSupport::Notifications.instrument('process_middleware.action_dispatch')

config/puma.rb

@@ -10,9 +10,13 @@
 min_threads_count = ENV.fetch('RAILS_MIN_THREADS', max_threads_count)
 threads min_threads_count, max_threads_count
 
-# Specifies the `port` that Puma will listen on to receive requests, default is 3000.
-#
-port        ENV.fetch('PORT', 3000)
+# Specifies the `port` that Puma will listen on to receive requests;
+# default is 3000.
+port ENV.fetch('PORT', 3000)
+
+# Specifies the `metrics_port` that Puma will listen on to export metrics;
+# default is 9393.
+# metrics_port = ENV.fetch('METRICS_PORT', 9393)
 
 # Specifies the `environment` that Puma will run in.
 #
@@ -51,7 +55,10 @@
 
 # Uncomment the following line once ruby is updated to 2.7 or greater to allow
 # the use of the puma-metrics plugin as we're using puma 6.0.0 or greater
+# Additional metrics from the Puma server to be exposed in the /metrics endpoint
 # plugin :metrics
+# Bind the metric server to "url". "tcp://" is the only accepted protocol.
+# metrics_url "tcp://0.0.0.0:#{metrics_port}" if Rails.env.development?
 
 # Use a custom log formatter to emit Puma log messages in a JSON format
 log_formatter do |str|