serverless-appsync-plugin dropped support for several APIs in the same stack starting from v2. This repository shows an example of how you can still deploy several APIs, even if they have shared schemas and resources by leveraging Serverless Framework Compose. This is the new reommended way to achieve this.

A common use case is to be able to build a public and private APIs that share some parts of the schema, dataSources and resolvers.

Shared resources

When working on a project with several APIs, they may share some resources. For example, they might need to access the same DynamoDB table. Thanks to Serverless Framework Compose, you can deploy those in a first "common" stack and then pass down the references as input parameters to the underlying services.

example:

services:
  common:
    path: common

  private:
      path: private
      dependsOn: common
      params:
        usersTableName: ${common.usersTableName}

    public:
      path: public
      dependsOn: common
      params:
        usersTableName: ${common.usersTableName}

For more information, refer to the official documentation

Shared and extended types

serverless-appsync-plugin supports defining your schema in several files. This allows you to place common parts of the schema in a file that will be shared by several APIs.

schema:
  - ../assets/schemas/*.graphql
  - schema.graphql

All the schema files will be merged together

You might also want to extend some types. For example, the admin API might need to expose a isAdmin field on the User type that you want to keep secret (unexposed) in the public API. You can do so thanks to schema extension. In your private schema, extend the User type:

extend type User {
  isAdmin: Boolean!
}

for more details and examples, check the common, public and private schema files.

Shared data sources and resolvers

When several APIs share some Queries and Mutations, you don't want to have to duplicate the dataSources and resolvers definitions, or your mapping templates. To avoid that, you can place them in separate files and reference them in your API definitions.

dataSources:
  # common dataSources
  - ${file(../assets/templates/dataSources.yml)}

resolvers:
  # common resolvers
  - ${file(../assets/templates/usersResolvers.yml)}

  # public only resolvers
  - Query.getMe: users
    Mutation.updateMe: users

See private/serverless.yml and public/serverless.yml