Appsync as Proxy to another Graphql server - amazon-web-services

Question

I have a existing graphql server provied by 3rd party. I also have my own backend running on EC2 to provide APIs.
I'm trying to build the appsync with aws-cdk for connecting to both 3rd party graphql and my backend instance also.
With the graphql server, appsync will act as proxy to forward queries only. My questions are:
Do we have anyway to load remote schema and populate it in appsync along with its schema?
How can we forward the requests to another graphql server using aws-cdk? I'm trying something like this:
private get _requestMappingTemplate(): string {
return `
{
"version": "2018-05-29",
"method": "GET",
"resourcePath": $util.toJson("/graphql"),
"params": {
"headers": {
"Authorization": "Bearer $ctx.request.headers.Authorization"
},
"body": {
"query": "$util.escapeJavaScript($ctx.info.getSelectionSetGraphQL())"
}
}
}`;
}
But from the aws doc, getSelectionSetGraphQL returns string representation of the selection set, formatted as GraphQL schema definition language (SDL). Although fragments aren't merged into the selection set
Is that possible to setup AppSync for forwarding request to another GraphQL servers? Any best practice to follow?

Answer 1

It's quite a bit more complicated. I'm still working on it, and the best I got so far is given below. It still drops query arguments, so has limited use.
#* TODO: Add some more interesting info to the operation name, e.g. a timestamp *#
#set($operationName = $context.info.parentTypeName)
#set($payloadBody = {
"query": "$util.str.toLower($context.info.parentTypeName) $operationName { $context.info.fieldName $context.info.selectionSetGraphQL }",
"operationName": $operationName,
"variables": $context.info.variables
})
{
"version" : "2018-05-29",
"operation": "Invoke",
"payload":{
"path": "/graphql",
"httpMethod": "POST",
"headers": $util.toJson($ctx.request.headers),
"requestContext": {
"authorizer": {
"claims": $context.identity.claims
}
},
"body": "$util.escapeJavaScript($util.toJson($payloadBody))",
"isBase64Encoded": false
},
}