Apollo Docs

API Reference: apollo-server

This API reference documents the exports from the apollo-server.


The core of an Apollo Server implementation. For an example, see the Building a server section within "Essentials".

constructor(options): <ApolloServer>


  • options: <Object>

    • typeDefs: <DocumentNode> | <Array<DocumentNode>> (required)

      DocumentNode(s) generated by using gql tag. They are string representations of GraphQL schema in the Schema Definition Language (SDL).

const typeDefs = gql`
  type Author {

new ApolloServer({
    context: ({ req }) => ({
        authScope: getScope(req.headers.authorization)
  • resolvers: <Object> (required)

    A map of resolvers for the types defined in typeDefs. The key should be the type name and the value should be a Function to be executed for that type.

  • context: <Object> | <Function>

    An object or function called with the current request that creates the context shared across all resolvers

new ApolloServer({
    context: ({ req }) => ({
        authScope: getScope(req.headers.authorization)
  • rootValue: <Any> | <Function>

    A value or function called with the parsed Document, creating the root value passed to the graphql executor. The function is useful if you wish to provide a different root value based on the query operation type.

new ApolloServer({
  rootValue: (documentAST) => ({
    const op = getOperationAST(documentNode)
    return op === 'mutation' ? mutationRoot : queryRoot;
  • mocks: <Object> | <Boolean>

    A boolean enabling the default mocks or object that contains definitions

  • mockEntireSchema: <Boolean>

    A boolean controlling whether existing resolvers are overridden by mocks. Defaults to true, meaning that all resolvers receive mocked values.

  • schemaDirectives: <Object>

    Contains definition of schema directives used in the typeDefs

  • introspection: <Boolean>

    Enables and disables schema introspection. Disabled in production by default.

  • playground: <Boolean> | <Object>

    Enables and disables playground and allows configuration of GraphQL Playground. The options can be found on GraphQL Playground's documentation

  • debug: <Boolean>

    Enables and disables development mode helpers. Defaults to true

  • validationRules: <Object>

    Schema validation rules

  • tracing, cacheControl: <Boolean>

    If set to true, adds tracing or cacheControl meta data to the GraphQL response. This is primarily intended for use with the deprecated Engine proxy. cacheControl can also be set to an object to specify arguments to the apollo-cache-control package, including defaultMaxAge, calculateHttpHeaders, and stripFormattedExtensions.

  • formatError, formatResponse: <Function>

    Functions to format the errors and response returned from the server, as well as the parameters to graphql execution(runQuery)

  • schema: <Object>

    An executable GraphQL schema that will override the typeDefs and resolvers provided. If you are using file uploads, you will have to add the Upload scalar to the schema, as it is not automatically added in case of setting the schema manually.

  • subscriptions: <Object> | <String> | false

    String defining the path for subscriptions or an Object to customize the subscriptions server. Set to false to disable subscriptions

    • path: <String>
    • keepAlive: <Number>
    • onConnect: <Function>
    • onDisconnect: <Function>
  • engine: <EngineReportingOptions> | boolean

    Provided the ENGINE_API_KEY environment variable is set, the engine reporting agent will be started automatically. The API key can also be provided as the apiKey field in an object passed as the engine field. See the EngineReportingOptions section for a full description of how to configure the reporting agent, including how to blacklist variables. When using the Engine proxy, this option should be set to false.

  • persistedQueries: <Object> | false

    The persisted queries option can be set to an object containing a cache field, which will be used to store the mapping between hash and query string.

  • cors: <Object | boolean> (apollo-server)

    Pass the integration-specific CORS options. false removes the CORS middleware and true uses the defaults. This option is only available to apollo-server. For other server integrations, place cors inside of applyMiddleware.



ApolloServer.listen(options): Promise


In apollo-server, the listen call starts the subscription server and passes the arguments directly to an http server Node.js' net.Server.listen method are supported.


Promise that resolves to an object that contains:


The applyMiddleware method is provided by the apollo-server-{integration} packages that use middleware, such as hapi and express. This function connects ApolloServer to a specific framework.


  • options: <Object>

    • app: <HttpServer> (required)

      Pass an instance of the server integration here.

    • path : <String>

      Specify a custom path. It defaults to /graphql if no path is specified.

    • cors: <Object | boolean> (express, hapi)

      Pass the integration-specific cors options. False removes the cors middleware and true uses the defaults.

    • bodyParserConfig: <Object | boolean> (express)

      Pass the body-parser options. False removes the body parser middleware and true uses the defaults.


The applyMiddleware method from apollo-server-express registration of middleware as shown in the example below:

const express = require('express');
const { ApolloServer } = require('apollo-server-express');
const { typeDefs, resolvers } = require('./schema');

const server = new ApolloServer({
  // These will be defined for both new or existing servers

const app = express();
// Additional middleware can be mounted at this point to run before Apollo.
app.use('*', jwtCheck, requireAuth, checkScope);

server.applyMiddleware({ app, path: '/specialUrl' }); // app is from an existing express app. Mount Apollo middleware here. If no path is specified, it defaults to `/graphql`.


The gql is a template literal tag. Template literals were introduced in recent versions of ECMAScript to provide embedded expressions (i.e. `A string with interpolated ${variables}`) and template literal tags exist to provide additional functionality for what would otherwise be a normal template literal.

In the case of GraphQL, the gql tag is used to surround GraphQL operation and schema language (which are represented as Strings), and makes it easier to differentiate from ordinary strings. This is particularly useful when performing static analysis on GraphQL language (e.g. to enable syntax highlighting, code generation, etc.) and avoids need for tools to "guess" if a string contains GraphQL language.


Import the gql template literal tag into the current context from the apollo-server or apollo-server-{integration} modules:

const { gql } = require('apollo-server');

Then, place GraphQL schema definitions (SDL), queries or other operations into the gql template literal tag. Keep in mind that template literals use the grave accent (`) and not normal quotation marks (e.g. not " or '):

const typeDefs = gql`
  type Author {


The makeExecutableSchema method is re-exported from apollo-server as a convenience.


  • options : <Object>
    • typeDefs: <GraphQLSchema> (required)
    • resolvers : <Object>
    • logger : <Object>
    • allowUndefinedInResolve = false
    • resolverValidationOptions = {}
    • directiveResolvers = null
    • schemaDirectives = null
    • parseOptions = {}
    • inheritResolversFromInterfaces = false


The addMockFunctionsToSchema method is re-exported from apollo-server as a convenience.

Given an instance of a GraphQLSchema and a mock object, modifies the schema (in place) to return mock data for any valid query that is sent to the server.

If preserveResolvers is set to true, existing resolve functions will not be overwritten to provide mock data. This can be used to mock some parts of the server and not others.


  • options: <Object>

    • schema: <GraphQLSchema> (required)

      Pass an executable schema (GraphQLSchema) to be mocked.

    • mocks: <Object>

      Should be a map of types to mock resolver functions, e.g.:

        Type: () => true,

      When mocks is not defined, the default scalar types (e.g. Int, Float, String, etc.) will be mocked.

    • preserveResolvers: <Boolean>

      When true, resolvers which were already defined will not be over-written with the mock resolver functions specified with mocks.


const { addMockFunctionsToSchema } = require('apollo-server');

// We'll make an assumption that an executable schema
// is already available from the `./schema` file.
const executableSchema = require('./schema');

  schema: executableSchema,
  mocks: {
    // Mocks the `Int` scalar type to always return `12345`.
    Int: () => 12345,

    // Mocks the `Movies` type to always return 'Titanic'.
    Movies: () => 'Titanic',
  preserveResolvers: false,


  • apiKey: string (required)

    API key for the service. Get this from Engine by logging in and creating a service. You may also specify this with the ENGINE_API_KEY environment variable the option takes precedence.

  • calculateSignature: (ast: DocumentNode, operationName: string) => string

    Specify the function for creating a signature for a query.

    See apollo-graphql's signature.ts for more information on how the default signature is generated.

  • reportIntervalMs: number

    How often to send reports to the Engine server. We'll also send reports when the report gets big see maxUncompressedReportSize.

  • maxUncompressedReportSize: number

    We send a report when the report size will become bigger than this size in bytes (default: 4MB). (This is a rough limit --- we ignore the size of the report header and some other top level bytes. We just add up the lengths of the serialized traces and signatures.)

  • endpointUrl: string

    The URL of the Engine report ingress server.

  • requestAgent: http.Agent | https.Agent | false

    HTTP(s) agent to be used for Apollo Engine metrics reporting. This accepts either an http.Agent or https.Agent and behaves the same as the agent parameter to Node.js' http.request.

  • debugPrintReports: boolean

    If set, prints all reports as JSON when they are sent.

  • maxAttempts: number

    Reporting is retried with exponential backoff up to this many times (including the original request). Defaults to 5.

  • minimumRetryDelayMs: number

    Minimum backoff for retries. Defaults to 100ms.

  • reportErrorFunction: (err: Error) => void

    By default, errors sending reports to Engine servers will be logged to standard error. Specify this function to process errors in a different way.

  • privateVariables: Array | boolean

    A case-sensitive list of names of variables whose values should not be sent to Apollo servers, or 'true' to leave out all variables. In the former case, the report will indicate that each private variable was redacted in the latter case, no variables are sent at all.

  • privateHeaders: Array | boolean

    A case-insensitive list of names of HTTP headers whose values should not be sent to Apollo servers, or 'true' to leave out all HTTP headers. Unlike with privateVariables, names of dropped headers are not reported.

  • handleSignals: boolean

    By default, EngineReportingAgent listens for the 'SIGINT' and 'SIGTERM' signals, stops, sends a final report, and re-sends the signal to itself. Set this to false to disable. You can manually invoke 'stop()' and 'sendReport()' on other signals if you'd like. Note that 'sendReport()' does not run synchronously so it cannot work usefully in an 'exit' handler.

  • rewriteError: (err: GraphQLError) => GraphQLError | null

    By default, all errors are reported to Apollo Engine. This function can be used to exclude specific errors from being reported. This function receives a copy of the GraphQLError and can manipulate it for the purposes of Apollo Engine reporting. The modified error (e.g. after changing the err.message property) should be returned or the function should return an explicit null to avoid reporting the error entirely. It is not permissable to return undefined.

  • schemaTag: String

    A human-readable name to tag this variant of a schema (i.e. staging, EU). Setting this value will cause metrics to be segmented in the Apollo Platform's UI. Additionally schema validation with a schema tag will only check metrics associate with the same string.

  • generateClientInfo: (GraphQLRequestContext) => ClientInfo AS 2.2

    Creates a client context(ClientInfo) based on the request pipeline's context, which contains values like the request, response, cache, and context. This generated client information will be provided to Apollo Engine and can be used to filter metrics. Set clientName to identify a particular client. Use clientVersion to specify a version for a client name. The default function will use the clientInfo field inside of GraphQL Query extensions.

    For advanced use cases when you already have an opaque string to identify your client (e.g. an API key, x509 certificate, or team codename), use the clientReferenceId field to add a reference to its internal identity. This client reference ID will not be displayed in the UI but will be available for cross-correspondence, so names and reference ids should have a one to one relationship.

    [WARNING] If you specify a clientReferenceId, Engine will treat the clientName as a secondary lookup, so changing a clientName may result in an unwanted experience.