Make AppSync and MappingTemplate L2-constructs work with CodePipeline deployments

Deploy an AppSync API with a schema definition file and resolver mapping templates in a CodePipeline using CloudFormation actions.

Use Case

I want to deploy an AppSync API in a CodePipeline and I don’t want to inline the schema into the CDK code because I want to generate model classes from it.

Currently, the schema definition must be provided either as a string or as an asset (not yet supported by CloudFormations actions). It is not possible to provide S3-locations without redefining the current L2-construct.

CDK source code:

https://github.com/aws/aws-cdk/blob/bf0113b01bb1c5548d87391b01670fca12636609/packages/%40aws-cdk/aws-appsync/lib/graphqlapi.ts#L236-L243

Proposed Solution

Provide S3-locations of the schema definition file and any resolver mapping templates to the synthesized template using CloudFormation parameters, similar to CfnParametersCode (see example here).

Since the number of mapping templates can be very high, a solution that requires only one parameter representing the S3-folder containing the mapping templates would be useful.

Creating an AppSync API and mapping templates could look like:

const schema = new cdk.CfnParameter(this, 'GraphQLSchemaS3Location');
const resolversDir = new cdk.CfnParameter(this, 'GraphQLMappingTemplatesS3Location');

const api = new appsync.GraphQLApi(this, 'GraphQLApi', {
  name: `GraphQLApi`,
  schemaDefinitionLocation: schema,
});

someDataSource.createQueryResolver({
  field: 'getHello',
  requestTemplate:  appsync.MappingTemplate.fromS3Location(resolversDir, 'getHello-request-mapping-template.vtl'),
  responseTemplate: appsync.MappingTemplate.fromS3Location(resolversDir, 'getHello-response-mapping-template.vtl'),
});

Other

Related question on Gitter.

• 👋 I may be able to implement this feature request
• ⚠️ This feature might incur a breaking change

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This is a 🚀 Feature Request

[BryanPan342]

Ah I see. I think this discussion would be great to keep open.

I think if we could change the issue name/message to reflect our discussion that would be fantastic!

[asterikx]

@BryanPan342 Thanks for you response.

Both would be all would be strings as that’s what the CloudFormation props take…

I don’t completely understand. Could you maybe sketch your solution? My idea was that the CDK would take care of uploading the referenced schema/resolver files to S3 and use the corresponding S3 locations (strings) as input parameters to the synthesized CFN template during deployment. Very similar to how lambda.CfnParametersCode, see this example.

Since pipelines.CdkPipeline now supports Assets, I think sth. like the following would best cover all use cases (cdk deploy and pipeline deployments using pipelines.CdkPipeline)

const api = new appsync.GraphQLApi(this, 'GraphQLApi', {
  name: `GraphQLApi`,
  schemaDefinition: appsync.SchemaDefinition.fromAsset('./schema.graphql'),
});

someDataSource.createQueryResolver({
  field: 'getHello',
  requestTemplate:  appsync.MappingTemplate.fromAsset('./resolvers/getHello-request-mapping-template.vtl'),
  responseTemplate: appsync.MappingTemplate.fromAsset('./resolvers/getHello-response-mapping-template.vtl'),
});