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The CDK Construct Library for AWS::AppSync

Project description

AWS AppSync Construct Library

---

cfn-resources: Stable

All classes with the Cfn prefix in this module (CFN Resources) are always stable and safe to use.

cdk-constructs: Experimental

The APIs of higher level constructs in this module are experimental and under active development. They are subject to non-backward compatible changes or removal in any future version. These are not subject to the Semantic Versioning model and breaking changes will be announced in the release notes. This means that while you may use them, you may need to update your source code when upgrading to a newer version of this package.


The @aws-cdk/aws-appsync package contains constructs for building flexible APIs that use GraphQL.

Example

Example of a GraphQL API with AWS_IAM authorization resolving into a DynamoDb backend data source.

GraphQL schema file schema.graphql:

type demo {
  id: String!
  version: String!
}
type Query {
  getDemos: [ test! ]
}
input DemoInput {
  version: String!
}
type Mutation {
  addDemo(input: DemoInput!): demo
}

CDK stack file app-stack.ts:

# Example automatically generated without compilation. See https://github.com/aws/jsii/issues/826
import aws_cdk.aws_appsync as appsync
import aws_cdk.aws_dynamodb as db

api = appsync.GraphQLApi(stack, "Api",
    name="demo",
    schema_definition=appsync.SchemaDefinition.FILE,
    schema_definition_file=join(__dirname, "schema.graphql"),
    authorization_config=AuthorizationConfig(
        default_authorization=AuthorizationMode(
            authorization_type=appsync.AuthorizationType.IAM
        )
    ),
    xray_enabled=True
)

demo_table = db.Table(stack, "DemoTable",
    partition_key=Attribute(
        name="id",
        type=db.AttributeType.STRING
    )
)

demo_dS = api.add_dynamo_db_data_source("demoDataSource", demo_table)

# Resolver for the Query "getDemos" that scans the DyanmoDb table and returns the entire list.
demo_dS.create_resolver(
    type_name="Query",
    field_name="getDemos",
    request_mapping_template=MappingTemplate.dynamo_db_scan_table(),
    response_mapping_template=MappingTemplate.dynamo_db_result_list()
)

# Resolver for the Mutation "addDemo" that puts the item into the DynamoDb table.
demo_dS.create_resolver(
    type_name="Mutation",
    field_name="addDemo",
    request_mapping_template=MappingTemplate.dynamo_db_put_item(PrimaryKey.partition("id").auto(), Values.projecting("demo")),
    response_mapping_template=MappingTemplate.dynamo_db_result_item()
)

Imports

Any GraphQL Api that has been created outside the stack can be imported from another stack into your CDK app. Utilizing the fromXxx function, you have the ability to add data sources and resolvers through a IGraphQLApi interface.

# Example automatically generated without compilation. See https://github.com/aws/jsii/issues/826
imported_api = appsync.GraphQLApi.from_graph_qLApi_attributes(stack, "IApi",
    graphql_api_id=api.api_id,
    graphql_arn=api.arn
)
imported_api.add_dynamo_db_data_source("TableDataSource", table)

If you don't specify graphqlArn in fromXxxAttributes, CDK will autogenerate the expected arn for the imported api, given the apiId. For creating data sources and resolvers, an apiId is sufficient.

Permissions

When using AWS_IAM as the authorization type for GraphQL API, an IAM Role with correct permissions must be used for access to API.

When configuring permissions, you can specify specific resources to only be accessible by IAM authorization. For example, if you want to only allow mutability for IAM authorized access you would configure the following.

In schema.graphql:

# Example automatically generated without compilation. See https://github.com/aws/jsii/issues/826
type Mutation {
  updateExample(...): ...@aws_iam

In IAM:

{
   "Version": "2012-10-17",
   "Statement": [
      {
         "Effect": "Allow",
         "Action": [
            "appsync:GraphQL"
         ],
         "Resource": [
            "arn:aws:appsync:REGION:ACCOUNT_ID:apis/GRAPHQL_ID/types/Mutation/fields/updateExample"
         ]
      }
   ]
}

See documentation for more details.

To make this easier, CDK provides grant API.

Use the grant function for more granular authorization.

# Example automatically generated without compilation. See https://github.com/aws/jsii/issues/826
role = iam.Role(stack, "Role",
    assumed_by=iam.ServicePrincipal("lambda.amazonaws.com")
)
api = appsync.GraphQLApi(stack, "API",
    definition=definition
)

api.grant(role, appsync.IamResource.custom("types/Mutation/fields/updateExample"), "appsync:GraphQL")

IamResource

In order to use the grant functions, you need to use the class IamResource.

  • IamResource.custom(...arns) permits custom ARNs and requires an argument.
  • IamResouce.ofType(type, ...fields) permits ARNs for types and their fields.
  • IamResource.all() permits ALL resources.

Generic Permissions

Alternatively, you can use more generic grant functions to accomplish the same usage.

These include:

  • grantMutation (use to grant access to Mutation fields)
  • grantQuery (use to grant access to Query fields)
  • grantSubscription (use to grant access to Subscription fields)
# Example automatically generated without compilation. See https://github.com/aws/jsii/issues/826
# For generic types
api.grant_mutation(role, "updateExample")

# For custom types and granular design
api.grant(role, appsync.IamResource.of_type("Mutation", "updateExample"), "appsync:GraphQL")

Code-First Schema

CDK offers the ability to generate your schema in a code-first approach. A code-first approach offers a developer workflow with:

  • modularity: organizing schema type definitions into different files
  • reusability: simplifying down boilerplate/repetitive code
  • consistency: resolvers and schema definition will always be synced

The code-first approach allows for dynamic schema generation. You can generate your schema based on variables and templates to reduce code duplication.

Code-First Example

We are going to reference the example through a code-first approach.

# Example automatically generated without compilation. See https://github.com/aws/jsii/issues/826
import aws_cdk.aws_appsync as appsync
import aws_cdk.aws_dynamodb as db

api = appsync.GraphQLApi(stack, "Api",
    name="demo",
    schema_definition=appsync.SchemaDefinition.CODE,
    authorization_config=AuthorizationConfig(
        default_authorization=AuthorizationMode(
            authorization_type=appsync.AuthorizationType.IAM
        )
    )
)

demo_table = db.Table(stack, "DemoTable",
    partition_key=Attribute(
        name="id",
        type=db.AttributeType.STRING
    )
)

demo_dS = api.add_dynamo_db_data_source("demoDataSource", "Table for Demos", demo_table)

# Schema Definition starts here

demo = api.add_type("demo",
    definition={
        "id": appsync.GraphqlType.string(is_required=True),
        "version": appsync.GraphqlType.string(is_required=True)
    }
)

GraphQL Types

One of the benefits of GraphQL is its strongly typed nature. We define the types within an object, query, mutation, interface, etc. as GraphQL Types.

GraphQL Types are the building blocks of types, whether they are scalar, objects, interfaces, etc. GraphQL Types can be:

  • Scalar Types: Id, Int, String, AWSDate, etc.
  • Object Types: types that you generate (i.e. demo from the example above)
  • Interface Types: abstract types that define the base implementation of other Intermediate Types

More concretely, GraphQL Types are simply the types appended to variables. Referencing the object type Demo in the previous example, the GraphQL Types is String! and is applied to both the names id and version.

Intermediate Types

Intermediate Types are abstractions above Scalar Types. They have a set of defined fields, where each field corresponds to another type in the system. Intermediate Types will be the meat of your GraphQL Schema as they are the types defined by you.

Intermediate Types include:

Interface Types

Interface Types are abstract types that define the implementation of other intermediate types. They are useful for eliminating duplication and can be used to generate Object Types with less work.

You can create Interface Types externally.

# Example automatically generated without compilation. See https://github.com/aws/jsii/issues/826
node = appsync.InterfaceType("Node",
    definition={
        "id": appsync.GraphqlType.string(is_required=True)
    }
)

Object Types

Object Types are types that you declare. For example, in the code-first example the demo variable is an Object Type. Object Types are defined by GraphQL Types and are only usable when linked to a GraphQL Api.

You can create Object Types in three ways:

  1. Object Types can be created externally.

    # Example automatically generated without compilation. See https://github.com/aws/jsii/issues/826
    api = appsync.GraphQLApi(stack, "Api",
        name="demo",
        schema_definition=appsync.SchemaDefinition.CODE
    )
    demo = appsync.ObjectType("Demo",
        defintion={
            "id": appsync.GraphqlType.string(is_required=True),
            "version": appsync.GraphqlType.string(is_required=True)
        }
    )
    
    api.append_to_schema(object.to_string())
    

    This method allows for reusability and modularity, ideal for larger projects. For example, imagine moving all Object Type definition outside the stack.

    scalar-types.ts - a file for scalar type definitions

    # Example automatically generated without compilation. See https://github.com/aws/jsii/issues/826
    required_string = appsync.GraphqlType.string(is_required=True)
    

    object-types.ts - a file for object type definitions

    # Example automatically generated without compilation. See https://github.com/aws/jsii/issues/826
    from ..scalar_types import required_string
    demo = appsync.ObjectType("Demo",
        defintion={
            "id": required_string,
            "version": required_string
        }
    )
    

    cdk-stack.ts - a file containing our cdk stack

    # Example automatically generated without compilation. See https://github.com/aws/jsii/issues/826
    from ..object_types import demo
    api.append_to_schema(demo.to_string())
    
  2. Object Types can be created externally from an Interface Type.

    # Example automatically generated without compilation. See https://github.com/aws/jsii/issues/826
    node = appsync.InterfaceType("Node",
        definition={
            "id": appsync.GraphqlType.string(is_required=True)
        }
    )
    demo = appsync.ObjectType.implement_interface("Demo",
        interface_types=[node],
        defintion={
            "version": appsync.GraphqlType.string(is_required=True)
        }
    )
    

    This method allows for reusability and modularity, ideal for reducing code duplication.

  3. Object Types can be created internally within the GraphQL API.

    # Example automatically generated without compilation. See https://github.com/aws/jsii/issues/826
    api = appsync.GraphQLApi(stack, "Api",
        name="demo",
        schema_definition=appsync.SchemaDefinition.CODE
    )
    api.add_type("Demo",
        defintion={
            "id": appsync.GraphqlType.string(is_required=True),
            "version": appsync.GraphqlType.string(is_required=True)
        }
    )
    

    This method provides easy use and is ideal for smaller projects.

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