(POOLER-181) Separate Dashboard from api

Allow the dashboard to run separately from the API, so that the
dashboard can be scaled appropriately.

Note - this implementation actually co-runs the api in the dashboard
instance to re-use the api code for the dashboard endpoints and other
v1 endpoints collecting the operating information.

bin/vmpooler

@@ -16,20 +16,21 @@ metrics = Vmpooler::Metrics.init(logger, config)
 
 torun_threads = []
 if ARGV.count == 0
-  torun = %i[api manager]
+  torun = %i[api manager dashboard]
 else
   torun = []
   torun << :api if ARGV.include? 'api'
   torun << :manager if ARGV.include? 'manager'
+  torun << :dashboard if ARGV.include? 'dashboard'
   exit(2) if torun.empty?
 end
 
-if torun.include? :api
-  api = Thread.new do
+if (torun & %i[api dashboard]).any?
+  api_or_dashboard = Thread.new do
     redis = Vmpooler.new_redis(redis_host, redis_port, redis_password)
     Vmpooler::API.execute(torun, config, redis, metrics, logger)
   end
-  torun_threads << api
+  torun_threads << api_or_dashboard
 elsif metrics.respond_to?(:setup_prometheus_metrics)
   # Run the cut down API - Prometheus Metrics only.
   prometheus_only_api = Thread.new do

lib/vmpooler/api.rb

@@ -3,7 +3,7 @@
 module Vmpooler
   class API < Sinatra::Base
     # Load API components
-    %w[helpers dashboard reroute v1 request_logger].each do |lib|
+    %w[helpers reroute v1 request_logger dashboard].each do |lib|
       require "vmpooler/api/#{lib}"
     end
     # Load dashboard components
@@ -42,12 +42,17 @@ module Vmpooler
         use Prometheus::Middleware::Exporter, path: metrics.endpoint
       end
 
-      if torun.include? :api
+      # Determine which parts of the API to actually run.
+      # The Dashboard also runs the API parts for its own "self-referencing" purposes, i.e. to re-use those parts
+      # that allow it to pull the information from redis.
+      if (torun & %i[api dashboard]).any?
         # Enable API request logging only if required
-        use Vmpooler::API::RequestLogger, logger: logger if config[:config]['request_logger']
+        use Vmpooler::API::RequestLogger, logger: logger if config[:config]['request_logger'] && (torun.include? :api)
 
-        use Vmpooler::Dashboard
-        use Vmpooler::API::Dashboard
+        if torun.include? :dashboard
+          use Vmpooler::Dashboard
+          use Vmpooler::API::Dashboard
+        end
         use Vmpooler::API::Reroute
         use Vmpooler::API::V1
       end

spec/integration/dashboard_spec.rb

@@ -27,7 +27,7 @@ describe Vmpooler::API do
 
     before(:each) do
       expect(app).to receive(:run!)
-      app.execute([:api], config, redis, nil, nil)
+      app.execute([:dashboard], config, redis, nil, nil)
       app.settings.set :config, auth: false
     end