# GraphQL Hive Client

[GraphQL Hive](https://graphql-hive.com) is a GraphQL schemas registry where you can host, manage
and collaborate on all your GraphQL schemas and operations, compatible with all architecture: schema
stitching, federation, or just a good old monolith.

GraphQL Hive is currently available as a hosted service to be used by all. We take care of the heavy
lifting behind the scenes be managing the registry, scaling it for your needs, to free your time to
focus on the most important things at hand.

## Installation

```
npm install @graphql-hive/client
```

## Basic Usage

Hive Client comes with generic client and plugins for [Envelop](https://envelop.dev) and
[Apollo Server](https://github.com/apollographql/apollo-server)

### With GraphQL Yoga

[GraphQL Yoga](https://www.the-guild.dev/graphql/yoga-server) is a cross-platform GraphQL sever
built on top of the envelop engine.

```ts
import { useHive } from '@graphql-hive/client'
import { createYoga } from '@graphql-yoga/node'

const server = createYoga({
  plugins: [
    useHive({
      enabled: true, // Enable/Disable Hive Client
      debug: true, // Debugging mode
      token: 'YOUR-TOKEN',
      // Schema reporting
      reporting: {
        // feel free to set dummy values here
        author: 'Author of the schema version',
        commit: 'git sha or any identifier'
      },
      usage: true // Collects schema usage based on operations
    })
  ]
})

server.start()
```

### With Envelop

If you're not familiar with Envelop - in "short" it's a lightweight JavaScript library for wrapping
GraphQL execution layer and flow, allowing developers to develop, share and collaborate on
GraphQL-related plugins, while filling the missing pieces in GraphQL implementations.

Here's [more](https://github.com/dotansimha/envelop#envelop) on that topic.

```ts
import { envelop } from '@envelop/core'
import { useHive } from '@graphql-hive/client'

const envelopProxy = envelop({
  plugins: [
    useHive({
      enabled: true, // Enable/Disable Hive Client
      debug: true, // Debugging mode
      token: 'YOUR-TOKEN',
      // Schema reporting
      reporting: {
        // feel free to set dummy values here
        author: 'Author of the schema version',
        commit: 'git sha or any identifier'
      },
      usage: true // Collects schema usage based on operations
    })
  ]
})
```

### With Apollo Server

Thanks to the plugin system it's a matter of adding hiveApollo plugin to ApolloServer instance:

```ts
import { ApolloServer } from 'apollo-server'
import { hiveApollo } from '@graphql-hive/client'

const server = new ApolloServer({
  typeDefs,
  resolvers,
  plugins: [
    hiveApollo({
      enabled: true, // Enable/Disable Hive Client
      debug: true, // Debugging mode
      token: 'YOUR-TOKEN',
      reporting: {
        // feel free to set dummy values here
        author: 'Author of the latest change',
        commit: 'git sha or any identifier'
      },
      usage: true // Collects schema usage based on operations
    })
  ]
})
```

### With Other Servers

First you need to instantiate the Hive Client.

The `collectUsage` method accepts the same arguments as execute function of graphql-js and returns a
function that expects the execution result object.

- `collectUsage(args)` - should be called when a GraphQL execution starts.
- `finish(result)` (function returned by `collectUsage(args)`) - has to be invoked right after
  execution finishes.

```ts
import express from 'express'
import { graphqlHTTP } from 'express-graphql'
import { createHive } from '@graphql-hive/client'

const app = express()
const hive = createHive({
  enabled: true, // Enable/Disable Hive Client
  debug: true, // Debugging mode
  token: 'YOUR-TOKEN',
  reporting: {
    // feel free to set dummy values here
    author: 'Author of the latest change',
    commit: 'git sha or any identifier'
  },
  usage: true // Collects schema usage based operations
})

// Report Schema
hive.reportSchema({ schema: yourSchema })

app.post(
  '/graphql',
  graphqlHTTP({
    schema: yourSchema,
    async customExecuteFn(args) {
      // Collecting usage
      const finish = hive.collectUsage(args)
      const result = await execute(args)
      finish(result)
      return result
    }
  })
)
```

### Using the registry when Stitching

Stitching could be done in many ways, that's why `@graphql-hive/client` provide generic functions,
not something dedicated for stitching. Unfortunately the implementation of gateway + polling is up
to you.

Prerequisites:

- `HIVE_CDN_ENDPOINT` - the endpoint Hive generated for you in the previous step
- `HIVE_CDN_KEY` - the access key

The `createServicesFetcher` factory function returns another function that is responsible for
fetching a list of services from Hive's high-availability endpoint.

```ts
import { createServicesFetcher } from '@graphql-hive/client'

const fetchServices = createServicesFetcher({
  endpoint: process.env.HIVE_CDN_ENDPOINT,
  key: process.env.HIVE_CDN_KEY
})

// This is your GraphQL gateway with built-in polling mechanism, in which the `stitchServices` method is called every 10 seconds.
startMyGraphQLGateway({
  // a function that resolves a list of services to stitch them together
  async stitchServices() {
    const services = await fetchServices()

    return services.map(service => {
      return {
        sdl: service.sdl,
        url: service.url,
        checksum: service.id // to check if service's schema was modified
      }
    })
  },
  pollingInSec: 10 // every 10s
})
```

### Using the registry with Apollo Gateway

You can connect your Apollo Gateway with Hive client.

- `HIVE_CDN_ENDPOINT` - the endpoint Hive generated for you in the previous step
- `HIVE_CDN_KEY` - the access

```ts
import { ApolloGateway } from '@apollo/gateway'
import { ApolloServer } from '@apollo/server'
import { startStandaloneServer } from '@apollo/server/standalone'
import { createSupergraphManager } from '@graphql-hive/client'

const gateway = new ApolloGateway({
  // Apollo Gateway will fetch Supergraph from GraphQL Hive CDN
  supergraphSdl: createSupergraphManager({
    endpoint: HIVE_CDN_ENDPOINT,
    key: HIVE_CDN_KEY,
    pollIntervalInMs: 15_000
  })
})

const server = new ApolloServer({
  gateway
})

const { url } = await startStandaloneServer({ server })
console.log(`🚀 Server ready at ${url}`)
```

## Usage Reporting configuration

### Client Info

The schema usage operation information can be enriched with meta information that will be displayed
on the Hive dashboard in order to get a better understanding of the origin of an executed GraphQL
operation.

### GraphQL Yoga Example

```ts
import { useHive } from '@graphql-hive/client'
import { createYoga } from '@graphql-yoga/node'

const server = createYoga({
  plugins: [
    useHive({
      enabled: true, // Enable/Disable Hive Client
      token: 'YOUR-TOKEN',
      usage: {
        clientInfo(ctx: { req: Request }) {
          const name = ctx.req.headers.get('x-graphql-client-name')
          const version = ctx.req.headers.get('x-graphql-client-version') ?? 'missing'

          if (name) {
            return { name, version }
          }

          return null
        }
      }
    })
  ]
})

server.start()
```

#### Envelop Example

```ts
import { envelop } from '@envelop/core'
import { useHive } from '@graphql-hive/client'

const envelopProxy = envelop({
  plugins: [
    useHive({
      enabled: true, // Enable/Disable Hive Client
      token: 'YOUR-TOKEN',
      usage: {
        clientInfo(ctx: { req: Request }) {
          const name = ctx.req.headers.get('x-graphql-client-name')
          const version = ctx.req.headers.get('x-graphql-client-version') ?? 'missing'

          if (name) {
            return { name, version }
          }

          return null
        }
      }
    })
  ]
})
```

#### Apollo Server Example

```ts
import type { IncomingMessage } from 'http'
import { ApolloServer } from 'apollo-server'
import { hiveApollo } from '@graphql-hive/client'

const server = new ApolloServer({
  typeDefs,
  resolvers,
  plugins: [
    hiveApollo({
      enabled: true, // Enable/Disable Hive Client
      token: 'YOUR-TOKEN',
      usage: {
        clientInfo(ctx: { req: IncomingMessage }) {
          const name = ctx.req.headers['x-graphql-client-name']
          const version = ctx.req.headers['x-graphql-client-version'] ?? 'missing'

          if (name) {
            return { name, version }
          }

          return null
        }
      }
    })
  ]
})
```

### Sampling

#### Basic sampling

With `sampleRate` option, you're able to control the sampling rate of the usage reporting. Setting
it to `0.5` will result in 50% of the operations being sent to Hive. There is no guarantee that
every operation will be reported at least once (see `atLeastOnceSampler`).

Default: `1` (100%)

```typescript
useHive({
  /* ... other options ... */,
  usage: {
    sampleRate: 0.6 // 60% of the operations will be sent to Hive
  }
})
```

#### Dynamic sampling

GraphQL Hive client accepts a function that returns a number between 0 and 1. This allows you to
implement dynamic sampling based on the operation's context.

If `sampler` is defined, `sampleRate` is ignored.

A sample rate between 0 and 1.

- `0.0` = 0% chance of being sent
- `1.0` = 100% chance of being sent.
- `true` = 100%
- `false` = 0%

```typescript
useHive({
  /* ... other options ... */,
  usage: {
    sampler(samplingContext) {
      if (samplingContext.operationName === 'GetUser') {
        return 0.5 // 50% of GetUser operations will be sent to Hive
      }

      return 0.7; // 70% of the other operations will be sent to Hive
    }
  }
})
```

#### At-least-once sampling

If you want to make sure that every operation is reported at least once, you can use the
`atLeastOnceSampler`. Every operation is reported at least once, but every next occurrence is
decided by the sampler.

```typescript
import { useHive, atLeastOnceSampler} from '@graphql-hive/client';

useHive({
  /* ... other options ... */,
  usage: {
    sampler: atLeastOnceSampler({
      // Produces a unique key for a given GraphQL request.
      // This key is used to determine the uniqueness of a GraphQL operation.
      keyFn(samplingContext) {
        // Operation name is a good candidate for a key, but not perfect,
        // as not all operations have names
        // and some operations may have the same name but different body.
        return samplingContext.operationName;
      },
      sampler(_samplingContext) {
        const hour = new Date().getHours();

        if (hour >= 9 && hour <= 17) {
          return 0.3;
        }

        return 0.8;
      }
    })
  }
})
```

## Self-Hosting

To align the client with your own instance of GraphQL Hive, you should use `selfHosting` options in
the client configuration.

The example is based on GraphQL Yoga, but the same configuration applies to Apollo Server and
others.

```ts
import { useHive } from '@graphql-hive/client'
import { createYoga } from '@graphql-yoga/node'

const server = createYoga({
  plugins: [
    useHive({
      enabled: true,
      token: 'YOUR-TOKEN',
      selfHosting: {
        graphqlEndpoint: 'https://your-own-graphql-hive.com/graphql',
        applicationUrl: 'https://your-own-graphql-hive.com',
        usageEndpoint: 'https://your-own-graphql-hive.com/usage' // optional
      }
    })
  ]
})

server.start()
```

> The `selfHosting` options take precedence over the deprecated `options.hosting.endpoint` and
> `options.usage.endpoint`.