Merge branch 'main' into pr/99

* main:
  Wording
  Remove accessory images using tags rather than labels
  Update readme to point to ghcr.io/mrsked/mrsk
  Validate that all roles have hosts
  Commander needn't accumulate configuration
  Pull latest image tag, so we can identity it
  Default to deploying the config version
  Remove unneeded Dockerfile.dind, update Readme
  add D-in-D dockerfile, update Readme

lib/mrsk/configuration.rb

@@ -9,13 +9,12 @@ class Mrsk::Configuration
   delegate :service, :image, :servers, :env, :labels, :registry, :builder, to: :raw_config, allow_nil: true
   delegate :argumentize, :argumentize_env_with_secrets, to: Mrsk::Utils
 
-  attr_accessor :version
   attr_accessor :destination
   attr_accessor :raw_config
 
   class << self
-    def create_from(base_config_file, destination: nil, version: "missing")
-      raw_config = load_config_files(base_config_file, *destination_config_file(base_config_file, destination))
+    def create_from(config_file:, destination: nil, version: nil)
+      raw_config = load_config_files(config_file, *destination_config_file(config_file, destination))
 
       new raw_config, destination: destination, version: version
     end
@@ -38,14 +37,22 @@ class Mrsk::Configuration
       end
   end
 
-  def initialize(raw_config, destination: nil, version: "missing", validate: true)
+  def initialize(raw_config, destination: nil, version: nil, validate: true)
     @raw_config = ActiveSupport::InheritableOptions.new(raw_config)
     @destination = destination
-    @version = version
+    @declared_version = version
     valid? if validate
   end
 
 
+  def version=(version)
+    @declared_version = version
+  end
+
+  def version
+    @declared_version.presence || ENV["VERSION"] || current_commit_hash
+  end
+
   def abbreviated_version
     Mrsk::Utils.abbreviate_version(version)
   end
@@ -73,7 +80,7 @@ class Mrsk::Configuration
   end
 
   def primary_web_host
-    role(:web).hosts.first
+    role(:web).primary_host
   end
 
   def traefik_hosts
@@ -189,6 +196,12 @@ class Mrsk::Configuration
         raise ArgumentError, "You must specify a password for the registry in config/deploy.yml (or set the ENV variable if that's used)"
       end
 
+      roles.each do |role|
+        if role.hosts.empty?
+          raise ArgumentError, "No servers specified for the #{role.name} role"
+        end
+      end
+
       true
     end
 
@@ -203,4 +216,13 @@ class Mrsk::Configuration
     def role_names
       raw_config.servers.is_a?(Array) ? [ "web" ] : raw_config.servers.keys.sort
     end
+
+    def current_commit_hash
+      @current_commit_hash ||=
+        if system("git rev-parse")
+          `git rev-parse HEAD`.strip
+        else
+          raise "Can't use commit hash as version, no git repository found in #{Dir.pwd}"
+        end
+    end
 end