[aws-appsync] Deploy fails when trying to change datasource

[thiagothies]

When trying to remove a datasource and create a new one, the deploy fails with the message: Only one resolver is allowed per field.

Reproduction Steps

The first step is to deploy a stack with a simple data source:

const api = new appsync.GraphqlApi(this, 'Api', {
      name: 'demo',
      schema: appsync.Schema.fromAsset('src/schema.graphql'),
});
const lambdaFunction = new lambda.Function(this, 'lambdaId', {
      runtime: lambda.Runtime.NODEJS_12_X,
      code: lambda.Code.fromAsset('src'),
      handler: 'main.handler',
});
const lambdaDS = api.addLambdaDataSource('lambdaDS', lambdaFunction);
lambdaDS.createResolver({
      typeName: 'Query',
      fieldName: 'getDemos',
      requestMappingTemplate: appsync.MappingTemplate.lambdaRequest(),
      responseMappingTemplate: appsync.MappingTemplate.lambdaResult()
})

then when trying to change the datasource, deploying this:

const api = new appsync.GraphqlApi(this, 'Api', {
      name: 'demo',
      schema: appsync.Schema.fromAsset('src/schema.graphql'),
});
const otherDS = api.addNoneDataSource('otherDS')
otherDS.createResolver({
      typeName: 'Query',
      fieldName: 'getDemos',
      requestMappingTemplate: appsync.MappingTemplate.fromString('{}'),
      responseMappingTemplate: appsync.MappingTemplate.fromString(JSON.stringify([{id: '1', version: '1.0'}]))
})

it fails.

What did you expect to happen?

it should update the datasource and resolver, but apparently it's not deleting the old resolver (or not doing it in order), and the deploy is failing

I was trying to update the resolver, but it only works when I deploy twice, first time deleting the old one, and the second time creating the new one

What actually happened?

Deploy fails with message Only one resolver is allowed per field.

Only one resolver is allowed per field. (Service: AWSAppSync; Status Code: 400; Error Code: BadRequestException; Request ID: 3ab24c35-8cae-43c7-9abd-a506f6879f0c; Proxy: null)

Environment

• CDK CLI Version: 1.74.0

• Node.js Version:10.16.2

• OS: macos 10.15.7

• Language: javascript

Other

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This is 🐛 Bug Report

[p0wl]

We ran into this issue as well. Detaching the resolver manually in the console partially helped, because the new ds and resolver were created, but not attached to the field.

[BryanPan342]

hm.. from your comment

I was trying to update the resolver, but it only works when I deploy twice, first time deleting the old one, and the second time creating the new one

I would assume the problem lies in the fact that the CFN template isn't updating in the order we might want. I'm not an expert in the ordering of CFN updates but maybe someone who has more expertise in this domain can take this for a swing.

[p0wl]

Yeah, this is the case. Running into this again while trying to revert #12635... Any idea how we can move this forward?

[github-actions]

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