Lighthouse: Support for Apollo Federation

[juusopiikkila]

A while ago Apollo introduced a new strategy for merging GraphQL schemas together in a more sensible way than schema stitching. It would be great to see this supported in Lighthouse too.

https://www.apollographql.com/docs/apollo-server/federation/introduction/
https://www.apollographql.com/docs/apollo-server/federation/federation-spec/

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[spawnia]

Are you willing to work on this?

[sl0wik]

I'm also searching for a way to implement it. Anyone else working on it?

[juusopiikkila]

I could try but I don't think that I have a good enough understanding of the code to make that big implementations yet.

[RPSimon]

I'm trying to implement this too. Does anybody found some clear information about this specification, or examples from other implementations?

[matthewhall-ca]

@RPSimon here's a Ruby implementation of it https://github.com/Gusto/apollo-federation-ruby

[matthewhall-ca]

We're happy to fund development of this if anyone is interested!

[renepardon]

Hey,
if no one is doing this right now, I would read the specs and try to implement this.

[spawnia]

@renepardon go for it!

Make sure to check out https://github.com/nuwave/lighthouse/blob/master/CONTRIBUTING.md to get going. We put a big emphasis on tests!

[renepardon]

I came across the following idea:

key Directive: https://gist.github.com/renepardon/6751168cc12bc9b32f32c7897169d112
federation Query: https://gist.github.com/renepardon/58b34ba1be427fade9cd2f8020dd1d89
federation.graphql: https://gist.github.com/renepardon/a5a65a050893d56a8a9994b70c475a11
example schema.graphql: https://gist.github.com/renepardon/3654a2be62a1d7dc629126e386adfa7c

And last but not least an additional method within the SchemaPrinter class:

    /**
     * @param Schema $schema
     * @param array  $options
     *
     * @return string
     */
    public static function printFederatedSchema(Schema $schema, array $options = []): string
    {
        $fields = $directives = [];
        $originalQueryType = $schema->getQueryType();
        $federationFields = ['_service', '_entities'];
        $federationDirectives = ['external', 'requires', 'provides', 'key', 'extends'];

        foreach ($originalQueryType->getFields() as $key => $field) {
            if (in_array($key, $federationFields)) {
                continue;
            }

            $fields[] = $field;
        }

        foreach ($schema->getDirectives() as $directive) {
            if (in_array($directive->name, $federationDirectives)) {
                continue;
            }

            $directives[] = $directive;
        }

        $queryType = new ObjectType([
            'name'       => 'Query',
            'fields'     => $fields,
            'interfaces' => $originalQueryType->getInterfaces(),
        ]);

        $newSchema = new Schema([
            'query'        => $queryType,
            'mutation'     => $schema->getMutationType(),
            'subscription' => $schema->getSubscriptionType(),
            'directives'   => $directives,
        ]);

        return self::printFilteredSchema(
            $newSchema,
            static function (Directive $type) {
                return !Directive::isSpecifiedDirective($type);
            },
            static function ($type) {
                return !Type::isBuiltInType($type);
            },
            $options
        );
    }

What's missing so far? Within the printFilteredSchema I have the option federated available but the @key(...), @extends etc. directives are not yet printed into the sdl field of _Service type.
Maybe you have an idea how to do this without extending the ObjectType.

[jerredhurst]

@renepardon - My team would be happy to help you work on a solution to this. What is the best way to get involved?

[renepardon]

@jerredhurst Right now I no longer work on it. I switched to NestJS

[spawnia]

@renepardon could you put up your WIP as a PR?

[RodriigoGS]

Is anyone working on it?

[renepardon]

@RodriigoGS Feel free to continue https://github.com/nuwave/lighthouse/pull/1051

[spawnia]

@renepardon @RodriigoGS i pulled the changes of #1051 to a branch. Whoever wants to work on it can fork and branch from there. Thanks

[gwardwell]

Is anyone actively looking at this? I have a team that's interested in developing GraphQL servers using Lighthouse, but we're using Apollo Federation and would need that support to really make it work.

[renepardon]

https://github.com/webonyx/graphql-php/issues/552 is still open. Problem is also that most of the methods used within the _graphql-php_ library are private which makes it pretty hard to extend/adjust the library as required for federation to work. You need to copy a lot of things just to make small adjustments within the schema printer. And I don't think it's a good idea to do so. This way you would just manage your own version of GraphQL library.

[spawnia]

Let's see if we can make the SchemaPrinter extendable at least: https://github.com/webonyx/graphql-php/issues/552#issuecomment-641105589

I would be fine with maintaining a modified version of the SchemaPrinter for Federation, as it seems to be a really popular and useful addition to Lighthouse.

[gwardwell]

Would php-graphql-federation help? It’s built to extend webonyx/graphql-php with federation and recommend by Apollo.

[spawnia]

Feel free to fork, branch from https://github.com/nuwave/lighthouse/tree/federation and give it a try.

[issuehunt-app[bot]]

@matthewhall-ca has funded $200.00 to this issue.

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[matthewhall-ca]

Looking to fund to get this developed - feel free to email my address on my profile if you want to discuss specifics or need a larger bounty for this feature

[RodriigoGS]

If nobody else is interested, I can see it in my spare time.

[tommyschmiedel]

Hey everyone, I've setup a simple package that provides Federation support for Lighthouse (service only).

A few things to note:

• [ ] It's a draft implementation that does not provide tests
• [ ] Lighthouses TypeRegistry and FieldFactory currently don't provide AST Nodes in the resolved types. That's why the package includes a patch file (see readme). It's a small change that can easily be fixed in Lighthouse itself
• [ ] The package provides a simple mechanism for resolving entities (see readme), but the final approach should be discussed by the community
• [ ] Relations currently have to be resolved by custom resolvers/builders. Maybe there is a way this can be done nicely; much like relationships work in Lighthouse itself

I hope someone who's willing to implement this as a core feature can find a good starting point in the repo. Also thanks to everyone who tried implementing this - definitely helped a lot!

You can find the repo here: https://github.com/awardis/federation

If you have trouble getting this package to work I'm willing to provide an example project.

@matthewhall-ca Bounty goes to the one implementing this into core :-)

[spawnia]

I have been talking to @matthewhall-ca and will look into supporting this.

[matthewhall-ca]

Removing the funds from Issue Hunt as @spawnia and I have discussed direct compensation over email

[issuehunt-app[bot]]

@matthewhall-ca has cancelled funding for this issue.(Cancelled amount: $200.00) See it on IssueHunt

[sebbZA]

Hi, is this still something that is being worked on?

[spawnia]

https://github.com/nuwave/lighthouse/pull/1728 has a working version. There is a little bit of work to be done, mostly documentation. I plan to release it as an experimental feature soon.

[spawnia]

Released as an experimental feature as of https://github.com/nuwave/lighthouse/releases/tag/v5.6.0. Thanks to everyone involved and in particular @matthewhall-ca for getting this funded.