feat: add database accessory and update helloworld sample

models/samples/helloworld/base/base.k

@@ -1,6 +1,7 @@
 import models.schema.v1 as ac
 import models.schema.v1.component as cmp
 import models.schema.v1.component.container as c
+import models.schema.v1.accessories.database as db
 
 # base.k declares reuseable configurations for all stacks.
 
@@ -25,6 +26,13 @@ appConfiguration: ac.AppConfiguration {
                     workingDir: "/tmp"
                 }
             }
+            database: db.Database {
+                type: "aws"
+                engine: "mysql"
+                version: "5.7"
+                instanceType: "db.t3.micro"
+                accessInternet: True
+            }
         }
     }
 }

models/schema/v1/accessories/database.k

@@ -0,0 +1,67 @@
+schema Database: 
+    """ Database defines the delivery artifact of relational database service 
+    (rds) provided by a specified cloud vendor for the application. 
+
+    Attributes
+    ----------
+    type: str, default is Undefined, required. 
+        Type defines the specific cloud vendor that provides the rds. 
+    engine: str, default is Undefined, required. 
+        Engine defines the database engine to use. 
+    version: str, default is Undefined, required. 
+        Version defines the database engine version to use. 
+    instanceType: str, default is Undefined, required. 
+        InstanceType defines the type of the rds instance. 
+    size: int, default is 10, optional. 
+        Size defines the allocated storage size of the rds instance in GB.  
+    category: str, default is "Basic", optional. 
+        Category defines the edition of the rds instance. 
+    username: str, default is "root", optional. 
+        Username defines the operation account for the rds instance. 
+    securityIPs: [str], default is ["0.0.0.0/0"], optional. 
+        SecurityIPs defines the list of IP addresses allowed to access the 
+        rds instance. 
+    accessInternet: bool, default is False, optional. 
+        AccessInternet defines whether the rds instance is publicly accessible. 
+
+    Examples
+    --------
+    Instantiate a publicly accessible aws rds with mysql 5.7. 
+
+    import models.schema.v1.accessories.database as db
+
+    database: db.Database {
+        type: "aws"
+        engine: "mysql"
+        version: "5.7"
+        instanceType: "db.t3.micro"
+        accessInternet: True
+    }
+    """
+
+    # The specific cloud vendor that provides the rds. 
+    $type:              str
+
+    # The database engine to use. 
+    engine:             str
+
+    # The database engine version to use. 
+    version:            str
+
+    # The type of the rds instance. 
+    instanceType:       str
+
+    # The allocated storage size of the rds instance in GB. 
+    size?:              int = 10
+
+    # The edition of the rds instance. 
+    category?:          str = "Basic"
+
+    # The operation account for the rds instance. 
+    username?:          str = "root"
+
+    # The list of IP addresses allowed to access the rds instance. 
+    securityIPs?:       [str] = ["0.0.0.0/0"]
+
+    # Whether the rds instance is publicly accessible. 
+    accessInternet?:    bool = False

models/schema/v1/app_configuration.k

@@ -28,6 +28,8 @@ schema AppConfiguration:
     }
     """
 
+    __settings__: {str:str} = {"output_type" = "STANDALONE"}
+
     # Component defines the delivery artifact of one application.
     # Each application can be composed by multiple components.
     components?:                 {str:c.Component}

models/schema/v1/component/component.k

@@ -1,4 +1,5 @@
 import models.schema.v1.component.container as c
+import models.schema.v1.accessories.database as db
 
 schema Component:
     """ Component defines the delivery artifact of one application. Each component
@@ -11,6 +12,8 @@ schema Component:
         More info: https://kubernetes.io/docs/concepts/containers
     replicas: int, default is 2, required.
         Number of container replicas that should be ran.
+    database: db.Database, default is Undefined, optional. 
+        Database defines the relational database service provided by a specified cloud vendor. 
     labels: {str:str}, default is Undefined, optional.
         Labels are key/value pairs that are attached to the component.
     annotations: {str:str}, default is Undefined, optional.
@@ -41,6 +44,9 @@ schema Component:
     replicas:                   int = 2
 
     ###### Other metadata info
+    # The relatioinal database service provided by a specified cloud vendor. 
+    database?:                  db.Database
+
     # Labels and annotations can be used to attach arbitrary metadata as key-value pairs to resources.
     labels?:                    {str:str}
     annotations?:               {str:str}