wip cache banning

No expectation this works like this, is basically pseudo-code in parts.

app/jobs/notify_cache_job.rb

@@ -0,0 +1,45 @@
+##
+# Job to notify a cache of URLs to be purged or banned, given an object
+# (that must have a cached_urls method).
+#
+# Examples:
+#   NotifyCacheJob.perform(InfoRequest.first)
+#   NotifyCacheJob.perform(FoiAttachment.first)
+#   NotifyCacheJob.perform(Comment.first)
+
+require 'net/http'
+
+class Net::HTTP::Purge < Net::HTTP::Get
+  METHOD = 'PURGE'
+end
+
+class Net::HTTP::Ban < Net::HTTP::Get
+  METHOD = 'BAN'
+end
+
+class NotifyCacheJob < ApplicationJob
+  queue_as :default
+
+  def perform(object, method = nil)
+    urls = object.cached_urls
+    hosts = AlaveteliConfiguration.varnish_hosts
+    hosts.each do |host|
+      Net::HTTP.start('www.whatdotheyknow.com', 80, host, 6081) do |http|
+        urls.each do |url|
+          if url.include? '^'
+            request = Net::HTTP::Ban.new(url)
+          else
+            request = Net::HTTP::Purge.new(url)
+          end
+          response = http.request(request)
+          result = response.code
+          if result == "200"
+            Rails.logger.debug("PURGE: Purged URL #{url} at #{host}: #{result}")
+          else
+            Rails.logger.warn("PURGE: Unable to purge URL #{url} at #{host}: status #{result}")
+          end
+        end
+      end
+    end
+  end
+end

app/models/censor_rule.rb

@@ -75,6 +75,7 @@ def is_global?
   def expire_requests
     if info_request
       InfoRequestExpireJob.perform_later(info_request)
+      NotifyCacheJob.perform_later(info_request)
     elsif user
       InfoRequestExpireJob.perform_later(user, :info_requests)
     elsif public_body

app/models/comment.rb

@@ -208,4 +208,11 @@ def check_body_uses_mixed_capitals
       errors.add(:body, msg)
     end
   end
+
+  def cached_urls
+    [
+      request_path(info_request),
+      show_user_wall_path(url_name: user.url_name),
+    ]
+  end
 end

app/models/foi_attachment.rb

@@ -323,4 +323,10 @@ def body_as_html(dir, opts = {})
   def text_type?
     AlaveteliTextMasker::TextMask.include?(content_type)
   end
+
+  def cached_urls
+    [
+      request_path(incoming_message.info_request),
+    ]
+  end
 end

app/models/info_request.rb

@@ -1163,6 +1163,15 @@ def log_event(type, params, options = {})
     if !last_event_time || (event.created_at > last_event_time)
       update_column(:last_event_time, event.created_at)
     end
+    if AlaveteliConfiguration.varnish_hosts.present?
+      if type in ('comment', 'edit_comment', 'hide_comment')
+        NotifyCacheJob.perform_later(params.comment)
+      elsif type in ('edit_attachment')
+        NotifyCacheJob.perform_later(params.attachment)
+      else
+        NotifyCacheJob.perform_later(self)
+      end
+    end
     event
   end
 
@@ -1904,4 +1913,22 @@ def reindexable_attribute_changed?
       saved_change_to_attribute?(attr)
     end
   end
+
+  def cached_urls
+    [
+      '/',
+      public_body_path(self.body),
+      request_path(self),
+      request_details_path(self),
+      '^/list*',
+      do_track_path({ track_type='request_updates', info_request=self }, feed='feed'),
+      '^/feed/list/*',
+      do_track_path({ track_type='public_body_updates', public_body=public_body }, feed='feed'),
+      do_track_path({ track_type='user_updates', tracked_user=user }, feed='feed'),
+      user_path(user),
+      show_user_wall_path(url_name: user.url_name),
+      public_body_path(self),
+      '^/body/list',
+    ]
+  end
 end

app/models/public_body.rb

@@ -968,4 +968,12 @@ def update_missing_email_tag
   def missing_email?
     !has_request_email?
   end
+
+  def cached_urls
+    [
+      public_body_path(self),
+      list_public_bodies_path,
+      '^/body/list',
+    ]
+  end
 end

app/models/user.rb

@@ -713,4 +713,10 @@ def update_pro_account
   def content_limit(content)
     content_limits[content]
   end
+
+  def cached_urls
+    [
+      user_path(self),
+    ]
+  end
 end

config/general.yml-example

@@ -627,6 +627,20 @@ EXCEPTION_NOTIFICATIONS_TO:
 # ---
 MAX_REQUESTS_PER_USER_PER_DAY: 6
 
+# If you're running behind Varnish set this to work out where to send purge
+# requests. Otherwise, don't set it.
+#
+# VARNISH_HOSTS - Array of Strings (default: nil)
+#
+# Examples:
+#
+#   VARNISH_HOSTS:
+#     - host1
+#     - host2
+#
+# ---
+VARNISH_HOSTS: null
+
 # Adding a value here will enable Google Analytics on all non-admin pages for
 # non-admin users.
 #