envelop

envelop is a lightweight JavaScript (/TypeScript) 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.

envelop aims to extend the GraphQL execution flow by adding plugins that enrich the feature set of your application.

@envelop/core:

Envelop is created and maintained by The Guild, and used in production by our clients.

Envelop Key Concepts

Lightweight
Wraps the entire GraphQL pipeline, based on plugins
Low-level API for extending the execution layer
Agnostic to GraphQL Engine
Agnostic to the HTTP layer
Agnostic to the schema tools
Plugins-based usage
No vendor lock-in
Amazing TypeScript support

Getting Started

Start by adding the core of Envelop to your codebase:

yarn add graphql @envelop/core

Then, create a simple Envelop based on your GraphQL schema:

import * as GraphQLJS from 'graphql'
import { envelop, useEngine, useSchema } from '@envelop/core'

const mySchema = buildSchema(/* ... */) // GraphQLSchema

const getEnveloped = envelop({
  plugins: [useEngine(GraphQLJS), useSchema(mySchema)]
})

The result of envelop is a function that allows you to get everything you need for the GraphQL execution: parse, validate, contextBuilder and execute. Use that to run the client's GraphQL queries. Here's a pseudo-code example of how it should look like:

const httpServer = createServer()

httpServer.on('request', async (req, res) => {
  // Here you get the alternative methods that are bundled with your plugins
  // You can also pass the "req" to make it available for your plugins or GraphQL context.
  const { parse, validate, contextFactory, execute, schema } = getEnveloped({ req })

  // Parse the initial request and validate it
  const { query, variables } = JSON.parse(req.payload)
  const document = parse(query)
  const validationErrors = validate(schema, document)

  if (validationErrors.length > 0) {
    return res.end(JSON.stringify({ errors: validationErrors }))
  }

  // Build the context and execute
  const context = await contextFactory(req)
  const result = await execute({
    document,
    schema,
    variableValues: variables,
    contextValue: context
  })

  // Send the response
  res.end(JSON.stringify(result))
})

httpServer.listen(3000)

Behind the scenes, this simple workflow allows you to use Envelop plugins and hook into the entire request handling flow.

Here's a simple example for collecting metrics and logging all incoming requests, using the built-in plugins:

const getEnveloped = envelop({
  plugins: [useEngine(GraphQLJS), useSchema(schema), useLogger(), useTiming()]
})

You can read more about here

Integrations / Examples

You can find the integrations and compatibility list, and code-based examples here

Available Plugins

You can explore all plugins in our Plugins Hub. If you wish your plugin to be listed here and under PluginsHub, feel free to add your plugin information in this file and create a Pull Request!

We provide a few built-in plugins within the @envelop/core, and many more plugins as standalone packages.

Envelop's Plugin Hub

Sharing / Composing `envelop`s

After an envelop has been created, you can share it with others as a complete layer of plugins. This is useful if you wish to create a predefined layer of plugins, and share it with others. You can use it as a shell and as a base for writing shareable pieces of servers.

You can read more about Sharing and Composing Envelops here.

Write your own plugin!

Envelop plugins are just objects with functions, that provide contextual implementation for before/after each phase, with a flexible API.

Here's a simple example that allows you to print the execution params:

const myPlugin = {
  onExecute({ args }) {
    console.log('Execution started!', { args })

    return {
      onExecuteDone({ result }) {
        console.log('Execution done!', { result })
      }
    }
  }
}

const getEnveloped = envelop({
  plugins: [
    /// ... other plugins ...,
    myPlugin
  ]
})