Type-GraphQL with support for Cloudflare Workers

About

Type-GraphQL does not work out of the box on Cloudflare Workers and requires a few small changes in order to get it working.

Global Metadata

getMetadataStorage.ts relies on global to be the global variable to hold all metadata. However in Cloudflare this does not exist. So a check for globalThis was added and if its not found then we fallback to global.

Node fs Module

Cloudflare Workers are not a Node environment. Some Node packages have been polyfilled by the Cloudflare team but fs is not one of them. emitSchemaDefinitionFile.ts relies on @/helpers/filesystem which uses the Node fs module in order to interact with the file system. I have created a new version of this file for use with Cloudflare called logSchemaDefinitionFile.ts. This does a simple console.log of the GraphQL schema if the emit flag is turned on.

Other Node Compatability issues

There are some other instances of Node modules being used however they have all been polyfilled by the Cloudflare team. You need to add compatibility_flags = ["nodejs_compat"] to your wrangler.toml file.

One more thing, GraphQL Subscriptions

GraphQL Subscriptions are currently not supported by Cloudflare Workers due to a technical limitation in Workers, see the following error:

✘ [ERROR] Uncaught (in promise) Error: Cannot perform I/O on behalf of a different request. I/O objects (such as streams, request/response bodies, and others) created in the context of one request handler cannot be accessed from a different request's handler. This is a limitation of Cloudflare Workers which allows us to improve overall performance.

TypeGraphQL relies on Apollo's graphql-subscriptions library in order to power its subscriptions feature, which also does not work on Cloudflare without modification. At first I considered removing this dependency altogether, however, the types from this library are used throughout TypeGraphQL and it would be a nontrivial change to remove it.

Instead I opted to patch the issue using patch-package. You can copy the patch from the patches folder and install it into your project using the following procedure.

• Create a patches folder in the root of your project
• Copy the patch from this lib into your patches folder
• Install patch-package dependency: npm i patch-package
• Run the patches: npx patch-package

This will modify pubsub.js in the graphql-subscriptions lib to use the node events module as Cloudflare wants it.

If you have made it this far, that is it! You should now be able to use TypeGraphQL in your Cloudflare Worker.

Developing

Branching

• master: Tracks the master branch from upstream: [email protected]:MichalLytek/type-graphql.git
• cloudflare: Contains the changes to TypeGraphQL for compatibility with Cloudflare Workers.

Integration

• Checkout master and pull the latest upstream master.
• Create a new integration branch off of cloudflare and merge the changes from master.
• Fix any conflicts as needed.
• Run the build. (npm run build).
• Run the tests and make sure everything is passing (npm test).
• Merge the changes into cloudflare.

Distribution

• Create release tag and push to github
• npm run build
• npm pack
• Upload output zip to github