(DIO-2675) Undo pool size template overrides

This implements a delete method for pooltemplate that removes the
override hash from redis and then resets triggers a reset of the pool.

It also implements a delete method for poolsize that removes the
override hash from redis. Unlike pooltemplate, it does not reset the
pool.

docs/API.md

@@ -743,6 +743,27 @@ $ curl -X POST -H "Content-Type: application/json" -d '{"debian-7-i386":"2","deb
 }
 ```
 
+##### DELETE /config/poolsize/<pool>
+
+Delete an overridden pool size. This results in the values from VMPooler's config being used.
+
+Return codes:
+* 200 - when nothing was changed but no error occurred
+* 201 - size reset successful
+* 401 - when not authorized
+* 404 - pool does not exist
+* 405 - The endpoint is disabled because experimental features are disabled
+
+```
+$ curl -X DELETE -u jdoe --url vmpooler.example.com/api/v1/poolsize/almalinux-8-x86_64
+Enter host password for user 'jdoe':
+```
+```json
+{
+  "ok": true
+}
+```
+
 ##### POST /config/pooltemplate
 
 Change the template configured for a pool, and replenish the pool with instances built from the new template.
@@ -775,6 +796,27 @@ $ curl -X POST -H "Content-Type: application/json" -d '{"debian-7-i386":"templat
 }
 ```
 
+##### DELETE /config/pooltemplate/<pool>
+
+Delete an overridden pool template. This results in the values from VMPooler's config being used.
+
+Return codes:
+* 200 - when nothing was changed but no error occurred
+* 201 - template reset successful
+* 401 - when not authorized
+* 404 - pool does not exist
+* 405 - The endpoint is disabled because experimental features are disabled
+
+```
+$ curl -X DELETE -u jdoe --url vmpooler.example.com/api/v1/pooltemplate/almalinux-8-x86_64
+Enter host password for user 'jdoe':
+```
+```json
+{
+  "ok": true
+}
+```
+
 ##### POST /poolreset
 
 Clear all pending and ready instances in a pool, and deploy replacements

lib/vmpooler.rb

@@ -133,8 +133,13 @@ def self.config(filepath = 'vmpooler.yaml')
       parsed_config[:pools] = load_pools_from_redis(redis)
     end
 
+    # retain a copy of the pools that were observed at startup
+    serialized_pools = Marshal.dump(parsed_config[:pools])
+    parsed_config[:pools_at_startup] = Marshal.load(serialized_pools)
+
     # Create an index of pools by title
     parsed_config[:pool_index] = pool_index(parsed_config[:pools])
+    parsed_config[:pool_index_at_startup] = pool_index(parsed_config[:pools_at_startup])
 
     parsed_config[:pools].each do |pool|
       parsed_config[:pool_names] << pool['name']

lib/vmpooler/api/v1.rb

@@ -28,6 +28,10 @@ def pools
       Vmpooler::API.settings.config[:pools]
     end
 
+    def pools_at_startup
+      Vmpooler::API.settings.config[:pools_at_startup]
+    end
+
     def pool_exists?(template)
       Vmpooler::API.settings.config[:pool_names].include?(template)
     end
@@ -289,6 +293,33 @@ def update_user_metrics(operation, vmname)
       puts 'd', "[!] [#{poolname}] failed while evaluating usage labels on '#{vmname}' with an error: #{e}"
     end
 
+    def reset_pool_size(poolname)
+      result = { 'ok' => false }
+
+      pool_index_live = pool_index(pools)
+      pool_index_original = pool_index(pools_at_startup)
+
+      pools_updated = 0
+      sync_pool_sizes
+
+      pool_size_now = pools[pool_index_live[poolname]]['size']
+      pool_size_original = pools_at_startup[pool_index_original[poolname]]['size']
+      result['pool_size_before_reset'] = pool_size_now
+      result['pool_size_before_overrides'] = pool_size_original
+
+      unless pool_size_now.to_i == pool_size_original.to_i
+        pools[pool_index_live[poolname]]['size'] = pool_size_original.to_i
+        backend.hdel('vmpooler__config__poolsize', poolname)
+        backend.sadd('vmpooler__pool__undo_size_override', poolname)
+        pools_updated += 1
+        status 201
+      end
+
+      status 200 unless pools_updated > 0
+      result['ok'] = true
+      result
+    end
+
     def update_pool_size(payload)
       result = { 'ok' => false }
 
@@ -309,6 +340,33 @@ def update_pool_size(payload)
       result
     end
 
+    def reset_pool_template(poolname)
+      result = { 'ok' => false }
+
+      pool_index_live = pool_index(pools)
+      pool_index_original = pool_index(pools_at_startup)
+
+      pools_updated = 0
+      sync_pool_templates
+
+      template_now = pools[pool_index_live[poolname]]['template']
+      template_original = pools_at_startup[pool_index_original[poolname]]['template']
+      result['template_before_reset'] = template_now
+      result['template_before_overrides'] = template_original
+
+      unless template_now == template_original
+        pools[pool_index_live[poolname]]['template'] = template_original
+        backend.hdel('vmpooler__config__template', poolname)
+        backend.sadd('vmpooler__pool__undo_template_override', poolname)
+        pools_updated += 1
+        status 201
+      end
+
+      status 200 unless pools_updated > 0
+      result['ok'] = true
+      result
+    end
+
     def update_pool_template(payload)
       result = { 'ok' => false }
 
@@ -1375,6 +1433,26 @@ def delete_ondemand_request(request_id)
       JSON.pretty_generate(result)
     end
 
+    delete "#{api_prefix}/config/poolsize/:pool/?" do
+      content_type :json
+      result = { 'ok' => false }
+
+      if config['experimental_features']
+        need_token! if Vmpooler::API.settings.config[:auth]
+
+        if pool_exists?(params[:pool])
+          result = reset_pool_size(params[:pool])
+        else
+          metrics.increment('config.invalid.unknown')
+          status 404
+        end
+      else
+        status 405
+      end
+
+      JSON.pretty_generate(result)
+    end
+
     post "#{api_prefix}/config/poolsize/?" do
       content_type :json
       result = { 'ok' => false }
@@ -1406,6 +1484,26 @@ def delete_ondemand_request(request_id)
       JSON.pretty_generate(result)
     end
 
+    delete "#{api_prefix}/config/pooltemplate/:pool/?" do
+      content_type :json
+      result = { 'ok' => false }
+
+      if config['experimental_features']
+        need_token! if Vmpooler::API.settings.config[:auth]
+
+        if pool_exists?(params[:pool])
+          result = reset_pool_template(params[:pool])
+        else
+          metrics.increment('config.invalid.unknown')
+          status 404
+        end
+      else
+        status 405
+      end
+
+      JSON.pretty_generate(result)
+    end
+
     post "#{api_prefix}/config/pooltemplate/?" do
       content_type :json
       result = { 'ok' => false }

lib/vmpooler/pool_manager.rb

@@ -784,6 +784,10 @@ def time_passed?(_event, time)
     #   - Fires when a pool reset is requested
     #   - Additional options
     #       :poolname
+    # :undo_override
+    #   - Fires when a pool override removal is requested
+    #   - Additional options
+    #       :poolname
     #
     def sleep_with_wakeup_events(loop_delay, wakeup_period = 5, options = {})
       exit_by = Time.now + loop_delay
@@ -826,6 +830,11 @@ def sleep_with_wakeup_events(loop_delay, wakeup_period = 5, options = {})
               break if pending
             end
 
+            if options[:undo_override]
+              break if redis.sismember('vmpooler__pool__undo_template_override', options[:poolname])
+              break if redis.sismember('vmpooler__pool__undo_size_override', options[:poolname])
+            end
+
             if options[:pending_vm]
               pending_vm_count = redis.scard("vmpooler__pending__#{options[:poolname]}")
               break unless pending_vm_count == 0
@@ -880,7 +889,7 @@ def check_pool(pool,
               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, pending_vm: true, pool_reset: 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, pending_vm: true, pool_reset: true, undo_override: true)
 
             unless maxloop == 0
               break if loop_count >= maxloop
@@ -1044,11 +1053,14 @@ def update_pool_size(pool)
         break if poolsize.nil?
 
         poolsize = Integer(poolsize)
-        break if poolsize == pool['size']
+        pool_size_now = pool['size']
+        break if poolsize == pool_size_now
 
         mutex.synchronize do
           pool['size'] = poolsize
         end
+
+        $logger.log('s', "[*] [#{pool['name']}] size updated from #{pool_size_now} to #{poolsize}")
       end
     end
 
@@ -1066,6 +1078,39 @@ def reset_pool(pool)
       end
     end
 
+    def undo_override(pool, provider)
+      poolname = pool['name']
+      mutex = pool_mutex(poolname)
+      return if mutex.locked?
+
+
+      @redis.with_metrics do |redis|
+        break unless redis.sismember('vmpooler__pool__undo_template_override', poolname)
+
+        redis.srem('vmpooler__pool__undo_template_override', poolname)
+        template_now = pool['template']
+        template_original = $config[:pools_at_startup][$config[:pool_index_at_startup][poolname]]['template']
+
+        mutex.synchronize do
+          update_pool_template(pool, provider, template_original, template_now, redis)
+        end
+      end
+
+      @redis.with_metrics do |redis|
+        break unless redis.sismember('vmpooler__pool__undo_size_override', poolname)
+
+        redis.srem('vmpooler__pool__undo_size_override', poolname)
+        pool_size_now = pool['size']
+        pool_size_original = $config[:pools_at_startup][$config[:pool_index_at_startup][poolname]]['size']
+
+        mutex.synchronize do
+          pool['size'] = pool_size_original
+        end
+
+        $logger.log('s', "[*] [#{poolname}] size updated from #{pool_size_now} to #{pool_size_original}")
+      end
+    end
+
     def create_inventory(pool, provider, pool_check_response)
       inventory = {}
       begin
@@ -1300,6 +1345,9 @@ def _check_pool(pool, provider)
       # Reset a pool when poolreset is requested from the API
       reset_pool(pool)
 
+      # Undo overrides submitted via the api
+      undo_override(pool, provider)
+
       pool_check_response
     end