Agent Skill · Apollo GraphQL
apollo-server
Guide for building GraphQL servers with Apollo Server 5.x. Use this skill when: (1) setting up a new Apollo Server project, (2) writing resolvers or defining GraphQL schemas, (3) implementing authentication or authorization, (4) creating plugins or custom data sources, (5) troubleshooting Apollo Server errors or performance issues.
Skill body
Apollo Server 5.x Guide
Apollo Server is an open-source GraphQL server that works with any GraphQL schema. Apollo Server 5 is framework-agnostic and runs standalone or integrates with Express, Fastify, and serverless environments.
Quick Start
Step 1: Install
npm install @apollo/server graphql
For Express integration:
npm install @apollo/server @as-integrations/express5 express graphql cors
Step 2: Define Schema
const typeDefs = `#graphql
type Book {
title: String
author: String
}
type Query {
books: [Book]
}
`;
Step 3: Write Resolvers
const resolvers = {
Query: {
books: () => [
{ title: "The Great Gatsby", author: "F. Scott Fitzgerald" },
{ title: "1984", author: "George Orwell" },
],
},
};
Step 4: Start Server
Standalone (Recommended for prototyping):
The standalone server is great for prototyping, but for production services, we recommend integrating Apollo Server with a more fully-featured web framework such as Express, Koa, or Fastify. Swapping from the standalone server to a web framework later is straightforward.
import { ApolloServer } from "@apollo/server";
import { startStandaloneServer } from "@apollo/server/standalone";
const server = new ApolloServer({ typeDefs, resolvers });
const { url } = await startStandaloneServer(server, {
listen: { port: 4000 },
});
console.log(`Server ready at ${url}`);
Express:
import { ApolloServer } from "@apollo/server";
import { expressMiddleware } from "@as-integrations/express5";
import { ApolloServerPluginDrainHttpServer } from "@apollo/server/plugin/drainHttpServer";
import express from "express";
import http from "http";
import cors from "cors";
const app = express();
const httpServer = http.createServer(app);
const server = new ApolloServer({
typeDefs,
resolvers,
plugins: [ApolloServerPluginDrainHttpServer({ httpServer })],
});
await server.start();
app.use(
"/graphql",
cors(),
express.json(),
expressMiddleware(server, {
context: async ({ req }) => ({ token: req.headers.authorization }),
}),
);
await new Promise<void>((resolve) => httpServer.listen({ port: 4000 }, resolve));
console.log("Server ready at http://localhost:4000/graphql");
Schema Definition
Scalar Types
Int- 32-bit integerFloat- Double-precision floating-pointString- UTF-8 stringBoolean- true/falseID- Unique identifier (serialized as String)
Type Definitions
type User {
id: ID!
name: String!
email: String
posts: [Post!]!
}
type Post {
id: ID!
title: String!
content: String
author: User!
}
input CreatePostInput {
title: String!
content: String
}
type Query {
user(id: ID!): User
users: [User!]!
}
type Mutation {
createPost(input: CreatePostInput!): Post!
}
Enums and Interfaces
enum Status {
DRAFT
PUBLISHED
ARCHIVED
}
interface Node {
id: ID!
}
type Article implements Node {
id: ID!
title: String!
}
Resolvers Overview
Resolvers follow the signature: (parent, args, contextValue, info)
- parent: Result from parent resolver (root resolvers receive undefined)
- args: Arguments passed to the field
- contextValue: Shared context object (auth, dataSources, etc.)
- info: Field-specific info and schema details (rarely used)
const resolvers = {
Query: {
user: async (_, { id }, { dataSources }) => {
return dataSources.usersAPI.getUser(id);
},
},
User: {
posts: async (parent, _, { dataSources }) => {
return dataSources.postsAPI.getPostsByAuthor(parent.id);
},
},
Mutation: {
createPost: async (_, { input }, { dataSources, user }) => {
if (!user) throw new GraphQLError("Not authenticated");
return dataSources.postsAPI.create({ ...input, authorId: user.id });
},
},
};
Context Setup
Context is created per-request and passed to all resolvers.
interface MyContext {
token?: string;
user?: User;
dataSources: {
usersAPI: UsersDataSource;
postsAPI: PostsDataSource;
};
}
const server = new ApolloServer<MyContext>({
typeDefs,
resolvers,
});
// Standalone
const { url } = await startStandaloneServer(server, {
context: async ({ req }) => ({
token: req.headers.authorization || "",
user: await getUser(req.headers.authorization || ""),
dataSources: {
usersAPI: new UsersDataSource(),
postsAPI: new PostsDataSource(),
},
}),
});
// Express middleware
expressMiddleware(server, {
context: async ({ req, res }) => ({
token: req.headers.authorization,
user: await getUser(req.headers.authorization),
dataSources: {
usersAPI: new UsersDataSource(),
postsAPI: new PostsDataSource(),
},
}),
});
Reference Files
Detailed documentation for specific topics:
- Resolvers - Resolver patterns and best practices
- Context and Auth - Authentication and authorization
- Plugins - Server and request lifecycle hooks
- Data Sources - RESTDataSource and DataLoader
- Error Handling - GraphQLError and error formatting
- Troubleshooting - Common issues and solutions
Key Rules
Schema Design
- Use ! (non-null) for fields that always have values
- Prefer input types for mutations over inline arguments
- Use interfaces for polymorphic types
- Keep schema descriptions for documentation
Resolver Best Practices
- Keep resolvers thin - delegate to services/data sources
- Always handle errors explicitly
- Use DataLoader for batching related queries
- Return partial data when possible (GraphQL’s strength)
Performance
- Use
@deferand@streamfor large responses - Implement DataLoader to solve N+1 queries
- Consider persisted queries for production
- Use caching headers and CDN where appropriate
Ground Rules
- ALWAYS use Apollo Server 5.x patterns (not v4 or earlier)
- ALWAYS type your context with TypeScript generics
- ALWAYS use
GraphQLErrorfromgraphqlpackage for errors - NEVER expose stack traces in production errors
- PREFER
startStandaloneServerfor prototyping only - USE an integration with a server framework like Express, Koa, Fastify, Next, etc. for production apps
- IMPLEMENT authentication in context, authorization in resolvers
Skill frontmatter
license: MIT
compatibility: Node.js v20+, TypeScript 4.7+. Works with Express v4/v5, standalone, Fastify, and serverless.
metadata: {"author" => "apollographql", "version" => "1.0.0"}
allowed-tools: Bash(npm:*) Bash(npx:*) Bash(node:*) Read Write Edit Glob Grep
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