CDK AppSync Transformer Demo

Accompanying repo for blog post regarding CDK AppSync Transformations. Find the post here. If you have any questions feel free to reach out here or @KenWin0x539.

Pre-reqs

• Node JS
• AWS CDK
  • npm install -g aws-cdk

Dependencies

Transformation

• graphql-transformer-core
• graphql-dynamodb-transformer
• graphql-connection-transformer
• graphql-key-transformer
• graphql-function-transformer
• graphql-versioned-transformer
• graphql-auth-transformer
• graphql-appsync-transformer

You can find other available transformers here

Custom Transformer

• graphql-transformer-core
• graphql
• graphql-transformer-common
• graphql-mapping-template
• cloudform-types

Execution

cdk synth

Emits the synthesized CloudFormation template. Additionally, this will run our transformer. Resolvers and generated schema go to ./appsync directory locally. Refrain from editing the generated schema - make necessary changes in the root ./schema.graphql. The generated file will be overwritten.

cdk deploy

Deploys the stack with out generated schema, tables and resolvers.

Getting Amplify DataStore To Work

It's a little bit hacky, but this is what I have so far. Awaiting further suggestions or ideas for optimizing. There is no native integration for the model generation at the moment.

• amplify add api --apiId xxx
• Copy schema to frontend amplify direction
  • From frontend - cp ../api/appsync/schema.graphql ./amplify/#current-cloud-backend/api/api-dev/
  • From frontend - cp ../api/schema.graphql ./amplify/backend/api/api-dev/
• Modify ${FRONTEND_DIR}/amplify/backend/amplify-meta.json

"api": {
    "my-cool-api-dev": {
        "service": "AppSync",
        "providerPlugin": "awscloudformation",
        ...
        ...
    }
}

• amplify codegen models - This should now work... I know, it's not lovely.

Where Do We Go From Here?

We believe this would work much better as a CDK plugin or an npm package. Unfortunately, the CDK plugin system currently only supports credential providers at the moment. I played around with writing it in as a plugin (it sort of works), but you would have to write the cfdoc to a file and read it from your app to bring in the resources. Perhaps an opinionated AppSync API Construct would be best here.

I'm not sold on the transform.conf.json method for triggering the sync enablement. I went this route because this is what the Amplify libraries do. Originally I was going to have props passed in to the SchemaTransformer (there are still some remnants of this code as I decide what to do...).

Resources / References

• Amplify GraphQL Transform
• GraphQL Auto Transformer