AWS AppSync Construct Library

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

import aws_cdk.aws_appsync as appsync

Example

DynamoDB

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

CDK stack file app-stack.ts:

api = appsync.GraphqlApi(self, "Api",
    name="demo",
    definition=appsync.Definition.from_file(path.join(__dirname, "schema.graphql")),
    authorization_config=appsync.AuthorizationConfig(
        default_authorization=appsync.AuthorizationMode(
            authorization_type=appsync.AuthorizationType.IAM
        )
    ),
    xray_enabled=True
)

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

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

# Resolver for the Query "getDemos" that scans the DynamoDb table and returns the entire list.
# Resolver Mapping Template Reference:
# https://docs.aws.amazon.com/appsync/latest/devguide/resolver-mapping-template-reference-dynamodb.html
demo_dS.create_resolver("QueryGetDemosResolver",
    type_name="Query",
    field_name="getDemos",
    request_mapping_template=appsync.MappingTemplate.dynamo_db_scan_table(),
    response_mapping_template=appsync.MappingTemplate.dynamo_db_result_list()
)

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

# To enable DynamoDB read consistency with the `MappingTemplate`:
demo_dS.create_resolver("QueryGetDemosConsistentResolver",
    type_name="Query",
    field_name="getDemosConsistent",
    request_mapping_template=appsync.MappingTemplate.dynamo_db_scan_table(True),
    response_mapping_template=appsync.MappingTemplate.dynamo_db_result_list()
)

Aurora Serverless

AppSync provides a data source for executing SQL commands against Amazon Aurora Serverless clusters. You can use AppSync resolvers to execute SQL statements against the Data API with GraphQL queries, mutations, and subscriptions.

Aurora Serverless V1 Cluster

# Build a data source for AppSync to access the database.
# api: appsync.GraphqlApi
# Create username and password secret for DB Cluster
secret = rds.DatabaseSecret(self, "AuroraSecret",
    username="clusteradmin"
)

# The VPC to place the cluster in
vpc = ec2.Vpc(self, "AuroraVpc")

# Create the serverless cluster, provide all values needed to customise the database.
cluster = rds.ServerlessCluster(self, "AuroraCluster",
    engine=rds.DatabaseClusterEngine.AURORA_MYSQL,
    vpc=vpc,
    credentials={"username": "clusteradmin"},
    cluster_identifier="db-endpoint-test",
    default_database_name="demos"
)
rds_dS = api.add_rds_data_source("rds", cluster, secret, "demos")

# Set up a resolver for an RDS query.
rds_dS.create_resolver("QueryGetDemosRdsResolver",
    type_name="Query",
    field_name="getDemosRds",
    request_mapping_template=appsync.MappingTemplate.from_string("""
          {
            "version": "2018-05-29",
            "statements": [
              "SELECT * FROM demos"
            ]
          }
          """),
    response_mapping_template=appsync.MappingTemplate.from_string("""
            $utils.toJson($utils.rds.toJsonObject($ctx.result)[0])
          """)
)

# Set up a resolver for an RDS mutation.
rds_dS.create_resolver("MutationAddDemoRdsResolver",
    type_name="Mutation",
    field_name="addDemoRds",
    request_mapping_template=appsync.MappingTemplate.from_string("""
          {
            "version": "2018-05-29",
            "statements": [
              "INSERT INTO demos VALUES (:id, :version)",
              "SELECT * WHERE id = :id"
            ],
            "variableMap": {
              ":id": $util.toJson($util.autoId()),
              ":version": $util.toJson($ctx.args.version)
            }
          }
          """),
    response_mapping_template=appsync.MappingTemplate.from_string("""
            $utils.toJson($utils.rds.toJsonObject($ctx.result)[1][0])
          """)
)

Aurora Serverless V2 Cluster

# Build a data source for AppSync to access the database.
# api: appsync.GraphqlApi
# Create username and password secret for DB Cluster
secret = rds.DatabaseSecret(self, "AuroraSecret",
    username="clusteradmin"
)

# The VPC to place the cluster in
vpc = ec2.Vpc(self, "AuroraVpc")

# Create the serverless cluster, provide all values needed to customise the database.
cluster = rds.DatabaseCluster(self, "AuroraClusterV2",
    engine=rds.DatabaseClusterEngine.aurora_postgres(version=rds.AuroraPostgresEngineVersion.VER_15_5),
    credentials={"username": "clusteradmin"},
    cluster_identifier="db-endpoint-test",
    writer=rds.ClusterInstance.serverless_v2("writer"),
    serverless_v2_min_capacity=2,
    serverless_v2_max_capacity=10,
    vpc=vpc,
    default_database_name="demos",
    enable_data_api=True
)
rds_dS = api.add_rds_data_source_v2("rds", cluster, secret, "demos")

# Set up a resolver for an RDS query.
rds_dS.create_resolver("QueryGetDemosRdsResolver",
    type_name="Query",
    field_name="getDemosRds",
    request_mapping_template=appsync.MappingTemplate.from_string("""
          {
            "version": "2018-05-29",
            "statements": [
              "SELECT * FROM demos"
            ]
          }
          """),
    response_mapping_template=appsync.MappingTemplate.from_string("""
            $utils.toJson($utils.rds.toJsonObject($ctx.result)[0])
          """)
)

# Set up a resolver for an RDS mutation.
rds_dS.create_resolver("MutationAddDemoRdsResolver",
    type_name="Mutation",
    field_name="addDemoRds",
    request_mapping_template=appsync.MappingTemplate.from_string("""
          {
            "version": "2018-05-29",
            "statements": [
              "INSERT INTO demos VALUES (:id, :version)",
              "SELECT * WHERE id = :id"
            ],
            "variableMap": {
              ":id": $util.toJson($util.autoId()),
              ":version": $util.toJson($ctx.args.version)
            }
          }
          """),
    response_mapping_template=appsync.MappingTemplate.from_string("""
            $utils.toJson($utils.rds.toJsonObject($ctx.result)[1][0])
          """)
)

HTTP Endpoints

GraphQL schema file schema.graphql:

type job {
  id: String!
  version: String!
}

input DemoInput {
  version: String!
}

type Mutation {
  callStepFunction(input: DemoInput!): job
}

GraphQL request mapping template request.vtl:

{
  "version": "2018-05-29",
  "method": "POST",
  "resourcePath": "/",
  "params": {
    "headers": {
      "content-type": "application/x-amz-json-1.0",
      "x-amz-target":"AWSStepFunctions.StartExecution"
    },
    "body": {
      "stateMachineArn": "<your step functions arn>",
      "input": "{ "id": "$context.arguments.id" }"
    }
  }
}

GraphQL response mapping template response.vtl:

{
  "id": "${context.result.id}"
}

CDK stack file app-stack.ts:

api = appsync.GraphqlApi(self, "api",
    name="api",
    definition=appsync.Definition.from_file(path.join(__dirname, "schema.graphql"))
)

http_ds = api.add_http_data_source("ds", "https://states.amazonaws.com",
    name="httpDsWithStepF",
    description="from appsync to StepFunctions Workflow",
    authorization_config=appsync.AwsIamConfig(
        signing_region="us-east-1",
        signing_service_name="states"
    )
)

http_ds.create_resolver("MutationCallStepFunctionResolver",
    type_name="Mutation",
    field_name="callStepFunction",
    request_mapping_template=appsync.MappingTemplate.from_file("request.vtl"),
    response_mapping_template=appsync.MappingTemplate.from_file("response.vtl")
)

EventBridge

Integrating AppSync with EventBridge enables developers to use EventBridge rules to route commands for GraphQL mutations that need to perform any one of a variety of asynchronous tasks. More broadly, it enables teams to expose an event bus as a part of a GraphQL schema.

GraphQL schema file schema.graphql:

schema {
    query: Query
    mutation: Mutation
}

type Query {
    event(id:ID!): Event
}

type Mutation {
    emitEvent(id: ID!, name: String): PutEventsResult!
}

type Event {
    id: ID!
    name: String!
}

type Entry {
    ErrorCode: String
    ErrorMessage: String
    EventId: String
}

type PutEventsResult {
    Entries: [Entry!]
    FailedEntry: Int
}

GraphQL request mapping template request.vtl:

{
    "version" : "2018-05-29",
    "operation": "PutEvents",
    "events" : [
        {
            "source": "integ.appsync.eventbridge",
            "detailType": "Mutation.emitEvent",
            "detail": $util.toJson($context.arguments)
        }
    ]
}

GraphQL response mapping template response.vtl:

$util.toJson($ctx.result)'

This response mapping template simply converts the EventBridge PutEvents result to JSON. For details about the response see the documentation. Additional logic can be added to the response template to map the response type, or to error in the event of failed events. More information can be found here.

CDK stack file app-stack.ts:

import aws_cdk.aws_events as events


api = appsync.GraphqlApi(self, "EventBridgeApi",
    name="EventBridgeApi",
    definition=appsync.Definition.from_file(path.join(__dirname, "appsync.eventbridge.graphql"))
)

bus = events.EventBus(self, "DestinationEventBus")

data_source = api.add_event_bridge_data_source("NoneDS", bus)

data_source.create_resolver("EventResolver",
    type_name="Mutation",
    field_name="emitEvent",
    request_mapping_template=appsync.MappingTemplate.from_file("request.vtl"),
    response_mapping_template=appsync.MappingTemplate.from_file("response.vtl")
)

Amazon OpenSearch Service

AppSync has builtin support for Amazon OpenSearch Service (successor to Amazon Elasticsearch Service) from domains that are provisioned through your AWS account. You can use AppSync resolvers to perform GraphQL operations such as queries, mutations, and subscriptions.

import aws_cdk.aws_opensearchservice as opensearch

# api: appsync.GraphqlApi


user = iam.User(self, "User")
domain = opensearch.Domain(self, "Domain",
    version=opensearch.EngineVersion.OPENSEARCH_2_3,
    removal_policy=RemovalPolicy.DESTROY,
    fine_grained_access_control=opensearch.AdvancedSecurityOptions(master_user_arn=user.user_arn),
    encryption_at_rest=opensearch.EncryptionAtRestOptions(enabled=True),
    node_to_node_encryption=True,
    enforce_https=True
)
ds = api.add_open_search_data_source("ds", domain)

ds.create_resolver("QueryGetTestsResolver",
    type_name="Query",
    field_name="getTests",
    request_mapping_template=appsync.MappingTemplate.from_string(JSON.stringify({
        "version": "2017-02-28",
        "operation": "GET",
        "path": "/id/post/_search",
        "params": {
            "headers": {},
            "query_string": {},
            "body": {"from": 0, "size": 50}
        }
    })),
    response_mapping_template=appsync.MappingTemplate.from_string("""[
            #foreach($entry in $context.result.hits.hits)
            #if( $velocityCount > 1 ) , #end
            $utils.toJson($entry.get("_source"))
            #end
          ]""")
)

Merged APIs

AppSync supports Merged APIs which can be used to merge multiple source APIs into a single API.

import aws_cdk as cdk


# first source API
first_api = appsync.GraphqlApi(self, "FirstSourceAPI",
    name="FirstSourceAPI",
    definition=appsync.Definition.from_file(path.join(__dirname, "appsync.merged-api-1.graphql"))
)

# second source API
second_api = appsync.GraphqlApi(self, "SecondSourceAPI",
    name="SecondSourceAPI",
    definition=appsync.Definition.from_file(path.join(__dirname, "appsync.merged-api-2.graphql"))
)

# Merged API
merged_api = appsync.GraphqlApi(self, "MergedAPI",
    name="MergedAPI",
    definition=appsync.Definition.from_source_apis(
        source_apis=[appsync.SourceApi(
            source_api=first_api,
            merge_type=appsync.MergeType.MANUAL_MERGE
        ), appsync.SourceApi(
            source_api=second_api,
            merge_type=appsync.MergeType.AUTO_MERGE
        )
        ]
    )
)

Merged APIs Across Different Stacks

The SourceApiAssociation construct allows you to define a SourceApiAssociation to a Merged API in a different stack or account. This allows a source API owner the ability to associate it to an existing Merged API itself.

source_api = appsync.GraphqlApi(self, "FirstSourceAPI",
    name="FirstSourceAPI",
    definition=appsync.Definition.from_file(path.join(__dirname, "appsync.merged-api-1.graphql"))
)

imported_merged_api = appsync.GraphqlApi.from_graphql_api_attributes(self, "ImportedMergedApi",
    graphql_api_id="MyApiId",
    graphql_api_arn="MyApiArn"
)

imported_execution_role = iam.Role.from_role_arn(self, "ExecutionRole", "arn:aws:iam::ACCOUNT:role/MyExistingRole")
appsync.SourceApiAssociation(self, "SourceApiAssociation2",
    source_api=source_api,
    merged_api=imported_merged_api,
    merge_type=appsync.MergeType.MANUAL_MERGE,
    merged_api_execution_role=imported_execution_role
)

Merge Source API Update Within CDK Deployment

The SourceApiAssociationMergeOperation construct available in the awscdk-appsync-utils package provides the ability to merge a source API to a Merged API via a custom resource. If the merge operation fails with a conflict, the stack update will fail and rollback the changes to the source API in the stack in order to prevent merge conflicts and ensure the source API changes are always propagated to the Merged API.

Custom Domain Names

For many use cases you may want to associate a custom domain name with your GraphQL API. This can be done during the API creation.

import aws_cdk.aws_certificatemanager as acm
import aws_cdk.aws_route53 as route53

# hosted zone and route53 features
# hosted_zone_id: str
zone_name = "example.com"


my_domain_name = "api.example.com"
certificate = acm.Certificate(self, "cert", domain_name=my_domain_name)
schema = appsync.SchemaFile(file_path="mySchemaFile")
api = appsync.GraphqlApi(self, "api",
    name="myApi",
    definition=appsync.Definition.from_schema(schema),
    domain_name=appsync.DomainOptions(
        certificate=certificate,
        domain_name=my_domain_name
    )
)

# hosted zone for adding appsync domain
zone = route53.HostedZone.from_hosted_zone_attributes(self, "HostedZone",
    hosted_zone_id=hosted_zone_id,
    zone_name=zone_name
)

# create a cname to the appsync domain. will map to something like xxxx.cloudfront.net
route53.CnameRecord(self, "CnameApiRecord",
    record_name="api",
    zone=zone,
    domain_name=api.app_sync_domain_name
)

Log Group

AppSync automatically create a log group with the name /aws/appsync/apis/<graphql_api_id> upon deployment with log data set to never expire. If you want to set a different expiration period, use the logConfig.retention property.

To obtain the GraphQL API’s log group as a logs.ILogGroup use the logGroup property of the GraphqlApi construct.

import aws_cdk.aws_logs as logs


log_config = appsync.LogConfig(
    retention=logs.RetentionDays.ONE_WEEK
)

appsync.GraphqlApi(self, "api",
    authorization_config=appsync.AuthorizationConfig(),
    name="myApi",
    definition=appsync.Definition.from_file(path.join(__dirname, "myApi.graphql")),
    log_config=log_config
)

Schema

You can define a schema using from a local file using Definition.fromFile

api = appsync.GraphqlApi(self, "api",
    name="myApi",
    definition=appsync.Definition.from_file(path.join(__dirname, "schema.graphl"))
)

ISchema

Alternative schema sources can be defined by implementing the ISchema interface. An example of this is the CodeFirstSchema class provided in awscdk-appsync-utils

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.

# api: appsync.GraphqlApi
# table: dynamodb.Table

imported_api = appsync.GraphqlApi.from_graphql_api_attributes(self, "IApi",
    graphql_api_id=api.api_id,
    graphql_api_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.

Private APIs

By default all AppSync GraphQL APIs are public and can be accessed from the internet. For customers that want to limit access to be from their VPC, the optional API visibility property can be set to Visibility.PRIVATE at creation time. To explicitly create a public API, the visibility property should be set to Visibility.GLOBAL. If visibility is not set, the service will default to GLOBAL.

CDK stack file app-stack.ts:

api = appsync.GraphqlApi(self, "api",
    name="MyPrivateAPI",
    definition=appsync.Definition.from_file(path.join(__dirname, "appsync.schema.graphql")),
    visibility=appsync.Visibility.PRIVATE
)

See documentation for more details about Private APIs

Authorization

There are multiple authorization types available for GraphQL API to cater to different access use cases. They are:

• API Keys (AuthorizationType.API_KEY)

• Amazon Cognito User Pools (AuthorizationType.USER_POOL)

• OpenID Connect (AuthorizationType.OPENID_CONNECT)

• AWS Identity and Access Management (AuthorizationType.AWS_IAM)

• AWS Lambda (AuthorizationType.AWS_LAMBDA)

These types can be used simultaneously in a single API, allowing different types of clients to access data. When you specify an authorization type, you can also specify the corresponding authorization mode to finish defining your authorization. For example, this is a GraphQL API with AWS Lambda Authorization.

import aws_cdk.aws_lambda as lambda_
# auth_function: lambda.Function


appsync.GraphqlApi(self, "api",
    name="api",
    definition=appsync.Definition.from_file(path.join(__dirname, "appsync.test.graphql")),
    authorization_config=appsync.AuthorizationConfig(
        default_authorization=appsync.AuthorizationMode(
            authorization_type=appsync.AuthorizationType.LAMBDA,
            lambda_authorizer_config=appsync.LambdaAuthorizerConfig(
                handler=auth_function
            )
        )
    )
)

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:

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.

# api: appsync.IGraphqlApi
role = iam.Role(self, "Role",
    assumed_by=iam.ServicePrincipal("lambda.amazonaws.com")
)

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)

# api: appsync.IGraphqlApi
# role: iam.Role


# 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")

Pipeline Resolvers and AppSync Functions

AppSync Functions are local functions that perform certain operations onto a backend data source. Developers can compose operations (Functions) and execute them in sequence with Pipeline Resolvers.

# api: appsync.GraphqlApi


appsync_function = appsync.AppsyncFunction(self, "function",
    name="appsync_function",
    api=api,
    data_source=api.add_none_data_source("none"),
    request_mapping_template=appsync.MappingTemplate.from_file("request.vtl"),
    response_mapping_template=appsync.MappingTemplate.from_file("response.vtl")
)

AppSync Functions are used in tandem with pipeline resolvers to compose multiple operations.

# api: appsync.GraphqlApi
# appsync_function: appsync.AppsyncFunction


pipeline_resolver = appsync.Resolver(self, "pipeline",
    api=api,
    data_source=api.add_none_data_source("none"),
    type_name="typeName",
    field_name="fieldName",
    request_mapping_template=appsync.MappingTemplate.from_file("beforeRequest.vtl"),
    pipeline_config=[appsync_function],
    response_mapping_template=appsync.MappingTemplate.from_file("afterResponse.vtl")
)

JS Functions and Resolvers

JS Functions and resolvers are also supported. You can use a .js file within your CDK project, or specify your function code inline.

# api: appsync.GraphqlApi


my_js_function = appsync.AppsyncFunction(self, "function",
    name="my_js_function",
    api=api,
    data_source=api.add_none_data_source("none"),
    code=appsync.Code.from_asset("directory/function_code.js"),
    runtime=appsync.FunctionRuntime.JS_1_0_0
)

appsync.Resolver(self, "PipelineResolver",
    api=api,
    type_name="typeName",
    field_name="fieldName",
    code=appsync.Code.from_inline("""
            // The before step
            export function request(...args) {
              console.log(args);
              return {}
            }

            // The after step
            export function response(ctx) {
              return ctx.prev.result
            }
          """),
    runtime=appsync.FunctionRuntime.JS_1_0_0,
    pipeline_config=[my_js_function]
)

Learn more about Pipeline Resolvers and AppSync Functions here.

Introspection

By default, AppSync allows you to use introspection queries.

For customers that want to limit access to be introspection queries, the introspectionConfig property can be set to IntrospectionConfig.DISABLED at creation time. If introspectionConfig is not set, the service will default to ENABLED.

api = appsync.GraphqlApi(self, "api",
    name="DisableIntrospectionApi",
    definition=appsync.Definition.from_file(path.join(__dirname, "appsync.schema.graphql")),
    introspection_config=appsync.IntrospectionConfig.DISABLED
)

Query Depth Limits

By default, queries are able to process an unlimited amount of nested levels. Limiting queries to a specified amount of nested levels has potential implications for the performance and flexibility of your project.

api = appsync.GraphqlApi(self, "api",
    name="LimitQueryDepths",
    definition=appsync.Definition.from_file(path.join(__dirname, "appsync.schema.graphql")),
    query_depth_limit=2
)

Resolver Count Limits

You can control how many resolvers each query can process. By default, each query can process up to 10000 resolvers. By setting a limit AppSync will not handle any resolvers past a certain number limit.

api = appsync.GraphqlApi(self, "api",
    name="LimitResolverCount",
    definition=appsync.Definition.from_file(path.join(__dirname, "appsync.schema.graphql")),
    resolver_count_limit=2
)

Environment Variables

To use environment variables in resolvers, you can use the environmentVariables property and the addEnvironmentVariable method.

api = appsync.GraphqlApi(self, "api",
    name="api",
    definition=appsync.Definition.from_file(path.join(__dirname, "appsync.schema.graphql")),
    environment_variables={
        "EnvKey1": "non-empty-1"
    }
)

api.add_environment_variable("EnvKey2", "non-empty-2")