feat: add priorities to IP address assignment

app/controllers/ip_addresses_controller.rb

@@ -33,7 +33,7 @@ def destroy
   private
 
   def safe_params
-    params.require(:ip_address).permit(:ipv4, :ipv6, :hostname)
+    params.require(:ip_address).permit(:ipv4, :ipv6, :hostname, :priority)
   end
 
 end

app/models/ip_address.rb

@@ -9,6 +9,7 @@
 #  created_at :datetime
 #  updated_at :datetime
 #  hostname   :string(255)
+#  priority   :integer
 #
 
 class IPAddress < ApplicationRecord
@@ -18,5 +19,26 @@ class IPAddress < ApplicationRecord
   validates :ipv4, :presence => true, :uniqueness => true
   validates :hostname, :presence => true
   validates :ipv6, :uniqueness => {:allow_blank => true}
+  validates :priority, numericality: { greater_than_or_equal_to: 0, less_than_or_equal_to: 100, only_integer: true }
+
+  scope :order_by_priority, -> { order(priority: :desc) }
+
+  before_validation :set_default_priority
+
+  private
+
+  def set_default_priority
+    return if priority.present?
+
+    self.priority = 100
+  end
+
+  class << self
+
+    def select_by_priority
+      order(Arel.sql("RAND() * priority DESC")).first
+    end
+
+  end
 
 end

app/models/queued_message.rb

@@ -63,7 +63,7 @@ def send_bounce
 
   def allocate_ip_address
     if Postal.ip_pools? && self.message && pool = self.server.ip_pool_for_message(self.message)
-      self.ip_address = pool.ip_addresses.order("RAND()").first
+      self.ip_address = pool.ip_addresses.select_by_priority
     end
   end
 

app/views/ip_addresses/_form.html.haml

@@ -10,6 +10,19 @@
     .fieldSet__field
       = f.label :hostname, :class => 'fieldSet__label'
       .fieldSet__input= f.text_field :hostname, :class => 'input input--text'
+    .fieldSet__field
+      = f.label :priority, :class => 'fieldSet__label'
+      .fieldSet__input
+        = f.text_field :priority, :class => 'input input--text', placeholder: '100'
+        %p.fieldSet__text
+          This priority will determine the likelihood of this IP address being selected
+          for use when sending a message. The higher the number the more likely the IP
+          is to be chosen. By defalt, the priority is set to the maximum value of 100.
+          This can be used to warm up new IP addresses by adding them with a low priority.
+          To give an indication of how this works, if you have three IPs with 1, 50 and 100
+          as their priorities, and you send 100,000 emails, the priority 1 address will receive
+          a tiny percentage, the priority 50 will receive roughly 25% and the priority 100 will
+          receive roughly 75%.
 
   .fieldSetSubmit.buttonSet
     = f.submit :class => 'button button--positive js-form-submit'

app/views/ip_pools/_form.html.haml

@@ -12,16 +12,19 @@
           %td IPv4
           %td IPv6
           %td Hostname
+          %td Priority
       %tbody
-        - if @ip_pool.ip_addresses.empty?
+        - ips = @ip_pool.ip_addresses.order_by_priority
+        - if ips.empty?
           %tr
             %td.dataTable__empty{:colspan => 3} There are no IP addresses assigned to this pool yet.
         - else
-          - for ip in @ip_pool.ip_addresses
+          - for ip in ips
             %tr
               %td{:width => "20%"}= link_to ip.ipv4, [:edit, @ip_pool, ip], :class => "u-link"
-              %td{:width => "40%"}= ip.ipv6
-              %td{:width => "40%"}= ip.hostname
+              %td{:width => "35%"}= ip.ipv6
+              %td{:width => "35%"}= ip.hostname
+              %td{:width => "10%"}= ip.priority
     %p= link_to "Add an IP address to pool", [:new, @ip_pool, :ip_address], :class => "u-link"
 
 

db/migrate/20210727210551_add_priority_to_ip_addresses.rb

@@ -0,0 +1,6 @@
+class AddPriorityToIPAddresses < ActiveRecord::Migration[5.2]
+  def change
+    add_column :ip_addresses, :priority, :integer
+    IPAddress.where(priority: nil).update_all(priority: 100)
+  end
+end

db/schema.rb

@@ -10,7 +10,7 @@
 #
 # It's strongly recommended that you check this file into your version control system.
 
-ActiveRecord::Schema.define(version: 2020_07_17_083943) do
+ActiveRecord::Schema.define(version: 2021_07_27_210551) do
 
   create_table "additional_route_endpoints", id: :integer, options: "ENGINE=InnoDB DEFAULT CHARSET=utf8mb4", force: :cascade do |t|
     t.integer "route_id"
@@ -124,6 +124,7 @@
     t.datetime "created_at", precision: 6
     t.datetime "updated_at", precision: 6
     t.string "hostname"
+    t.integer "priority"
   end
 
   create_table "ip_pool_rules", id: :integer, options: "ENGINE=InnoDB DEFAULT CHARSET=utf8mb4", force: :cascade do |t|