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API Reference: apollo-server

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


The core of an Apollo Server implementation. For an example, see the getting-started article.

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({
  • 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: (integrationContext) => ({
        // Important: The `integrationContext` argument varies depending
        // on the specific integration (e.g. Express, Koa,  Lambda, etc.)
        // being used. See the table below for specific signatures.
        // For example, using Express's `authorization` header, and a
        // `getScope` method (intentionally left unspecified here):
        authScope: getScope(integrationContext.req.headers.authorization)
    IntegrationIntegration Context Signature
    Azure Functions{
      request: HttpRequest,
      context: Context
    Google Cloud Functions{ req: Request, res: Response }
    Cloudflare{ req: Request }
      req: express.Request,
      res: express.Response
      request: hapi.Request,
      h: hapi.ResponseToolkit
    Koa{ ctx: Koa.Context }
    AWS Lambda{
      event: APIGatewayProxyEvent,
      context: LambdaContext
    Micro{ req: MicroRequest, res: ServerResponse }
  • logger: Logger

    A logging implementation to be used in place of console. The implementation must provide the methods which satisfy the requirements of the Logger interface (i.e. it must provide debug, info, warn and error methods). When a custom logger is provided, it will receive all levels of logging and it is up to the logger itself to determine how it wishes to handle each level. When a custom logger is not provided, Apollo Server will default to outputting warn and error levels unless debug: true is specified, in which case it will output all log levels (i.e. debug through error).

    Additionally, this logger will be made available on the GraphQLRequestContext and available to plugins. This allows a plugin to, e.g., augment the logger on a per-request basis within the requestDidStart life-cycle hook.

  • 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 metadata 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

    If the APOLLO_KEY environment variable is set, the Apollo Studio reporting agent starts automatically. The API key can also be provided as the apiKey field in an object passed as the engine field. See EngineReportingOptions for a full description of how to configure the reporting agent, including how to include variable values and HTTP headers.

  • 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.

  • experimental_approximateDocumentStoreSizeMiB: number

    This property is experimental. It may be removed or change at any time, even within a patch release.

    When set, this sets the approximate size of the parsed/validated document store (in MiB). This cache is used to save the already parsed and validated DocumentNodes for re-use on subsequent queries which resolve to the same queryHash (a SHA-256 of incoming operation).

    When this property is omitted, the cache is still enabled with a default size of 30MiB, which is generally sufficient unless the server is processing a high number of unique operations.




Note: This method is only provided by the apollo-server package. For the apollo-server-{integration} packages, see applyMiddleware below.


  • options: <Object>

    When using the apollo-server package, calling listen on an instantiated ApolloServer will start the server by passing the specified (optional) options to a Node.js http.Server. For a full reference of the supported options, see the documentation for net.Server.listen.


Promise that resolves to an object containing the following properties:

  • url: <String>
  • subscriptionsPath: <String>
  • server: <http.Server>


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

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

    • bodyParserConfig: <Object | boolean> (express, koa)

    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`.


Similar to the applyMiddleware method above, though rather than applying the composition of the various Apollo Server middlewares which comprise a full-featured Apollo Server deployment (e.g. middleware for HTTP body parsing, GraphQL Playground, uploads and subscriptions) the getMiddleware simply returns the middleware.

The getMiddleware method takes the same arguments as applyMiddleware except app should not be passed. Instead, the result of getMiddleware must be added as a middleware directly to an existing application (e.g. with app.use(...)).

For example, for apollo-server-express, this means that rather than passing applyMiddleware an app which was already initiated from calling express(), and applyMiddleware "using" (i.e. app.use), the implementor will instead call app.use(...) on the result of getMiddleware with the same arguments.


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. Obtain an API key from Apollo Studio by logging in and creating a service. You can also specify an API key with the APOLLO_KEY environment variable. If you specify both, the apiKey option takes precedence.

  • logger: Logger

    By default, this will inherit from the logger provided to ApolloServer which defaults to console when not provided. If specified within the EngineReportingOptions it can be used to send engine reporting to a separate logger. If provided, the implementation must provide the methods which satisfy the requirements of the Logger interface (i.e. it must provide debug, info, warn and error methods).

  • 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 Apollo Studio, in milliseconds. We'll also send reports when the report reaches a size threshold specified by maxUncompressedReportSize.

  • maxUncompressedReportSize: number

    In addition to interval-based reporting, Apollo Server sends a report to Apollo Studio whenever the report's size exceeds this value in bytes (default: 4MB). Note that this is a rough limit. The size of the report's header and some other top-level bytes are ignored. The report size is limited to the sum of the lengths of serialized traces and signatures.

  • endpointUrl: string

    The URL of the Apollo Studio report ingress server.

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

    HTTP(s) agent to be used for Apollo Studio 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, any errors encountered while sending reports to Apollo Studio are logged to standard error. Specify this function to process errors in a different way.

  • sendVariableValues: { transform: (options: { variables: Record<string, any>, operationString?: string } ) => Record<string, any> } | { exceptNames: Array<String> } | { onlyNames: Array<String> } | { none: true } | { all: true }

    By default, Apollo Server does not send the values of any GraphQL variables to Apollo's servers, because variable values often contain the private data of your app's users. If you'd like variable values to be included in traces, set this option. This option can take several forms:

    • { none: true }: Don't send any variable values. (DEFAULT)
    • { all: true }: Send all variable values.
    • { transform: ({ variables, operationString}) => { ... } }: A custom function for modifying variable values. Keys added by the custom function will be removed, and keys removed will be added back with an empty value. For security reasons, if an error occurs within this function, all variable values will be replaced with [PREDICATE_FUNCTION_ERROR].
    • { exceptNames: [...] }: A case-sensitive list of names of variables whose values should not be sent to Apollo servers.
    • { onlyNames: [...] }: A case-sensitive list of names of variables whose values will be sent to Apollo servers.

    Defaults to not sending any variable values if both this parameter and the deprecated privateVariables are not set. The report will indicate each private variable key whose value was redacted by { none: true } or { exceptNames: [...] }.

  • privateVariables: Array<String> | boolean

    Will be deprecated in 3.0. Use the option sendVariableValues instead. Passing an array into privateVariables is equivalent to passing in { exceptNames: array } to sendVariableValues, and passing in true or false is equivalent to passing { none: true } or { all: true }, respectively.

    Note: An error will be thrown if both this deprecated option and its replacement, sendVariableValues are defined. In order to preserve the old default of privateVariables, which sends all variables and their values, pass in the sendVariableValues option: new ApolloServer({engine: {sendVariableValues: {all: true}}}).

  • sendHeaders: { exceptNames: Array<String> } | { onlyNames: Array<String> } | { all: boolean } | { none: boolean } By default, Apollo Server does not send the list of HTTP request headers and values to Apollo's servers, to protect private data of your app's users. If you'd like this information included in traces, set this option. This option can take several forms:

    • { none: true }: Drop all HTTP request headers. (DEFAULT)
    • { all: true }: Send the values of all HTTP request headers.
    • { exceptNames: [...] }: A case-insensitive list of names of HTTP headers whose values should not be sent to Apollo servers.
    • { onlyNames: [...] }: A case-insensitive list of names of HTTP headers whose values will be sent to Apollo servers.

    Defaults to not sending any request header names and values if both this parameter and the deprecated privateHeaders are not set. Unlike with sendVariableValues, names of dropped headers are not reported. The headers 'authorization', 'cookie', and 'set-cookie' are never reported.

  • privateHeaders: Array<String> | boolean

    Will be deprecated in 3.0. Use the sendHeaders option instead. Passing an array into privateHeaders is equivalent to passing { exceptNames: array } into sendHeaders, and passing true or false is equivalent to passing in { none: true } and { all: true }, respectively.

    Note: An error will be thrown if both this deprecated option and its replacement, sendHeaders, are defined. In order to preserve the old default of privateHeaders, which sends all request headers and their values, pass in the sendHeaders option: new ApolloServer({engine: {sendHeaders: {all: true}}}).

  • 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 Studio. This function can be used to exclude specific errors from being reported. This function receives a copy of the GraphQLError and can manipulate it before it's reported. The modified error (e.g., after changing the err.message property) should be returned, or the function can return null to avoid reporting the error entirely. It is not permissible to return undefined. Note that most GraphQLError fields, like path, will be copied from the original error to the new error: this way, you can just return new GraphQLError("message") without having to explicitly keep it associated with the same node. Specifically, only the message and extensions properties on the returned GraphQLError are observed. If extensions aren't specified, the original extensions are used.

  • schemaTag: String

    Will be deprecated in 3.0. Use the option graphVariant instead.

    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 associated with the same string.

  • graphVariant: String

    A human-readable name for the variant of a schema (such as staging or production). Setting this value will cause metrics to be segmented in Apollo Studio. Additionally, schema validation with a graph variant only checks metrics associated with the same variant.

  • reportTiming: Boolean | async (GraphQLRequestContextDidResolveOperation | GraphQLRequestContextDidEncounterErrors) => Boolean

    Specify whether to instrument an operation to send traces and metrics to Apollo. This may resolve to a boolean or a async function returning a promise resolving to a boolean. If the option resolves to false for an operation the operation will not be instrumented and no metrics information will be sent to Apollo.

    The function will receive a GraphQLRequestContextDidResolveOperation with client and operation information or a GraphQLRequestContextDiDEncounterErrors in the case an operation failed to resolve properly. This allows the choice of whether to include a given request in trace and metric reporting to be made on a per-request basis. The default value is true.

  • 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 Studio 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, Apollo Studio treats the clientName as a secondary lookup, so changing a clientName may result in an unwanted experience.

  • reportSchema: boolean

    Enables the automatic schema reporting feature of Apollo Server, which will cause it to periodically report the server's schema (when changes are detected) along with details about the runtime environment to Apollo Graph Manager. This feature removes the need to register schemas manually via apollo service:push in CI/CD pipelines.

  • overrideReportedSchema: string

    By default, the schema reported to Apollo Studio will be normalized, which might shift ordering and comments and remove whitespace. This option can be used to override the default schema. Any schema provided will not undergo normalization, which can be helpful to preserve details that normalization removes.

  • schemaReportingInitialDelayMaxMs: number

    By default, the schema reporter will wait a random amount of time between 0 and 10 seconds before making its first report at reporter startup. A longer range of times leads to more staggered starts, which reduces bandwidth since it makes it less likely that multiple servers will get asked to upload the same schema. However, in certain constrained environments (e.g. AWS Lambda), this wait time may be less desirable. This option can be used to change the maximum amount of time that the reporter will wait until it starts sending reports.

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