Merge branch 'basecamp:main' into buildpacks

lib/kamal/configuration/accessory.rb

@@ -32,7 +32,7 @@ class Kamal::Configuration::Accessory
   end
 
   def hosts
-    hosts_from_host || hosts_from_hosts || hosts_from_roles
+    hosts_from_host || hosts_from_hosts || hosts_from_roles || hosts_from_tags
   end
 
   def port
@@ -201,11 +201,31 @@ class Kamal::Configuration::Accessory
     end
 
     def hosts_from_roles
-      if accessory_config.key?("roles")
+      if accessory_config.key?("role")
+       config.role(accessory_config["role"])&.hosts
+      elsif accessory_config.key?("roles")
         accessory_config["roles"].flat_map { |role| config.role(role)&.hosts }
       end
     end
 
+    def hosts_from_tags
+      if accessory_config.key?("tag")
+        extract_hosts_from_config_with_tag(accessory_config["tag"])
+      elsif accessory_config.key?("tags")
+        accessory_config["tags"].flat_map { |tag| extract_hosts_from_config_with_tag(tag) }
+      end
+    end
+
+    def extract_hosts_from_config_with_tag(tag)
+      if (servers_with_roles = config.raw_config.servers).is_a?(Hash)
+        servers_with_roles.flat_map do |role, servers_in_role|
+          servers_in_role.filter_map do |host|
+            host.keys.first if host.is_a?(Hash) && host.values.first.include?(tag)
+          end
+        end
+      end
+    end
+
     def network
       accessory_config["network"] || DEFAULT_NETWORK
     end
@@ -213,6 +233,8 @@ class Kamal::Configuration::Accessory
     def ensure_valid_roles
       if accessory_config["roles"] && (missing_roles = accessory_config["roles"] - config.roles.map(&:name)).any?
         raise Kamal::ConfigurationError, "accessories/#{name}: unknown roles #{missing_roles.join(", ")}"
+      elsif accessory_config["role"] && !config.role(accessory_config["role"])
+        raise Kamal::ConfigurationError, "accessories/#{name}: unknown role #{accessory_config["role"]}"
       end
     end
 end

lib/kamal/configuration/docs/accessory.yml

@@ -46,13 +46,18 @@ accessories:
 
     # Accessory hosts
     #
-    # Specify one of `host`, `hosts`, or `roles`:
+    # Specify one of `host`, `hosts`, `role`, `roles`, `tag` or `tags`:
     host: mysql-db1
     hosts:
       - mysql-db1
       - mysql-db2
+    role: mysql
     roles:
       - mysql
+    tag: writer
+    tags:
+      - writer
+      - reader
 
     # Custom command
     #

lib/kamal/configuration/validator/accessory.rb

@@ -2,8 +2,8 @@ class Kamal::Configuration::Validator::Accessory < Kamal::Configuration::Validat
   def validate!
     super
 
-    if (config.keys & [ "host", "hosts", "roles" ]).size != 1
-      error "specify one of `host`, `hosts` or `roles`"
+    if (config.keys & [ "host", "hosts", "role", "roles", "tag", "tags" ]).size != 1
+      error "specify one of `host`, `hosts`, `role`, `roles`, `tag` or `tags`"
     end
 
     validate_docker_options!(config["options"])

lib/kamal/version.rb

@@ -1,3 +1,3 @@
 module Kamal
-  VERSION = "2.5.3"
+  VERSION = "2.6.0"
 end