(POOLER-153) Add endpoint for resetting a pool

This commit adds a capability to vmpooler to reset a pool, deleting its ready and pending instances and replacing them with fresh ones. Without this change vmpooler does not offer a mechanism to reset a pool without also changing its template.

lib/vmpooler/api/v1.rb

@@ -200,6 +200,17 @@ module Vmpooler
       result
     end
 
+    def reset_pool(payload)
+      result = { 'ok' => false }
+
+      payload.each do |poolname, count|
+        backend.sadd('vmpooler__poolreset', poolname)
+      end
+      status 201
+      result['ok'] = true
+      result
+    end
+
     def update_clone_target(payload)
       result = { 'ok' => false }
 
@@ -1063,6 +1074,44 @@ module Vmpooler
       JSON.pretty_generate(result)
     end
 
+    post "#{api_prefix}/poolreset/?" do
+      content_type :json
+      result = { 'ok' => false }
+
+      if config['experimental_features']
+        need_token! if Vmpooler::API.settings.config[:auth]
+
+        begin
+          payload = JSON.parse(request.body.read)
+          if payload
+            invalid = invalid_templates(payload)
+            if invalid.empty?
+              result = reset_pool(payload)
+            else
+              invalid.each do |bad_pool|
+                metrics.increment("poolreset.invalid.#{bad_pool}")
+              end
+              result[:bad_pools] = invalid
+              status 400
+            end
+          else
+            metrics.increment('poolreset.invalid.unknown')
+            status 404
+          end
+        rescue JSON::ParserError
+          status 400
+          result = {
+            'ok' => false,
+            'message' => 'JSON payload could not be parsed'
+          }
+        end
+      else
+        status 405
+      end
+
+      JSON.pretty_generate(result)
+    end
+
     post "#{api_prefix}/config/clonetarget/?" do
       content_type :json
       result = { 'ok' => false }

lib/vmpooler/pool_manager.rb

@@ -680,6 +680,10 @@ module Vmpooler
     #   - Fires when a template configuration update is requested
     #   - Additional options
     #       :poolname
+    # :pool_reset
+    #   - Fires when a pool reset is requested
+    #   - Additional options
+    #       :poolname
     #
     def sleep_with_wakeup_events(loop_delay, wakeup_period = 5, options = {})
       exit_by = Time.now + loop_delay
@@ -726,6 +730,10 @@ module Vmpooler
             end
           end
 
+          if options[:pool_reset]
+            break if $redis.sismember('vmpooler__poolreset', options[:poolname])
+          end
+
         end
 
         break if time_passed?(:exit_by, exit_by)
@@ -763,7 +771,7 @@ module Vmpooler
               loop_delay = (loop_delay * loop_delay_decay).to_i
               loop_delay = loop_delay_max if loop_delay > loop_delay_max
             end
-            sleep_with_wakeup_events(loop_delay, loop_delay_min, pool_size_change: true, poolname: pool['name'], pool_template_change: true, clone_target_change: true)
+            sleep_with_wakeup_events(loop_delay, loop_delay_min, pool_size_change: true, poolname: pool['name'], pool_template_change: true, clone_target_change: true, pool_reset: true)
 
             unless maxloop.zero?
               break if loop_count >= maxloop
@@ -917,6 +925,17 @@ module Vmpooler
       end
     end
 
+    def reset_pool(pool)
+      poolname = pool['name']
+      return unless $redis.sismember('vmpooler__poolreset', poolname)
+      $redis.srem('vmpooler__poolreset', poolname)
+      mutex = pool_mutex(poolname)
+      mutex.synchronize do
+        drain_pool(poolname)
+        $logger.log('s', "[*] [#{poolname}] reset has cleared ready and pending instances")
+      end
+    end
+
     def create_inventory(pool, provider, pool_check_response)
       inventory = {}
       begin
@@ -1125,6 +1144,9 @@ module Vmpooler
       # Remove VMs in excess of the configured pool size
       remove_excess_vms(pool)
 
+      # Reset a pool when poolreset is requested from the API
+      reset_pool(pool)
+
       pool_check_response
     end