Plugins with Apollo

Plugins let you extend Apollo Server's core functionality by performing custom operations in response to certain events. These events correspond to individual phases of the GraphQL request lifecycle, and to the startup of Apollo Server itself (see plugins in the Apollo documentation). For example, a basic logging plugin might log the GraphQL query string of each request sent to Apollo Server.

Custom plugins#

To create a plugin, declare a class annotated with the @Plugin() decorator, exported from the @nestjs/apollo package. For better code autocompletion, also implement the ApolloServerPlugin interface from the @apollo/server package.

import { ApolloServerPlugin, GraphQLRequestListener } from '@apollo/server';
import { Plugin } from '@nestjs/apollo';

@Plugin()
export class LoggingPlugin implements ApolloServerPlugin {
  async requestDidStart(): Promise<GraphQLRequestListener<any>> {
    console.log('Request started');
    return {
      async willSendResponse() {
        console.log('Will send response');
      },
    };
  }
}

With this in place, register LoggingPlugin as a provider:

@Module({
  providers: [LoggingPlugin],
})
export class CommonModule {}

Nest automatically instantiates the plugin and applies it to Apollo Server.

Using external plugins#

Apollo Server provides several plugins out of the box. To use an existing plugin, import it and add it to the plugins array:

import { ApolloServerPluginCacheControl } from '@apollo/server/plugin/cacheControl';

GraphQLModule.forRoot({
  // ...
  plugins: [ApolloServerPluginCacheControl({ defaultMaxAge: 5 })],
}),

Hint The ApolloServerPluginCacheControl plugin is exported from the @apollo/server/plugin/cacheControl entry point of the @apollo/server package.

Plugins with Mercurius#

Some of the existing Mercurius-specific Fastify plugins must be loaded after the Mercurius plugin in the plugin tree (see plugins in the Mercurius documentation).

Warningmercurius-upload is an exception: register it in the main file.

For this, MercuriusDriver exposes an optional plugins configuration option. It takes an array of objects with two properties: plugin and its options. For example, registering the cache plugin looks like this:

GraphQLModule.forRoot({
  driver: MercuriusDriver,
  // ...
  plugins: [
    {
      plugin: cache,
      options: {
        ttl: 10,
        policy: {
          Query: {
            add: true
          }
        }
      },
    }
  ]
}),