elasticgraph-apollo

ElasticGraph::Apollo

Implements the Apollo Federation Subgraph Spec, allowing an ElasticGraph application to be plugged into an Apollo-powered GraphQL server as a subgraph.

Note: this library only supports the v2 Federation specification.

Usage

First, add elasticgraph-apollo to your Gemfile:

gem "elasticgraph-apollo"

Finally, update your ElasticGraph schema artifact rake tasks in your Rakefile so that ElasticGraph::GraphQL::Apollo::SchemaDefinition::APIExtension is passed as one of the extension_modules:

require "elastic_graph/schema_definition/rake_tasks"
require "elastic_graph/apollo/schema_definition/api_extension"

ElasticGraph::SchemaDefinition::RakeTasks.new(
  schema_element_name_form: :snake_case,
  index_document_sizes: true,
  path_to_schema: "config/schema.rb",
  schema_artifacts_directory: artifacts_dir,
  extension_modules: [ElasticGraph::Apollo::SchemaDefinition::APIExtension]
)

That's it!

Federation Version Support

This library supports multiple versions of Apollo federation. As of Jan. 2024, it supports:

• v2.0
• v2.3
• v2.5
• v2.6

By default, the newest version is targeted. If you need an older version (e.g. because your organization is running an older Apollo version), you can configure it in your schema definition with:

schema.target_apollo_federation_version "2.3"

Testing Notes

This project uses https://github.com/apollographql/apollo-federation-subgraph-compatibility to verify compatibility with Apollo. Things to note:

• Run elasticgraph-apollo/script/test_compatibility to run the compatibility tests (the CI build runs this).
• Run elasticgraph-apollo/script/boot_eg_apollo_implementation to boot the ElasticGraph compatibility test implementation (can be useful for debugging test_compatibility failures).
• These scripts require some additional dependencies to be installed (such as docker, node, and npm).
• To get that to pass locally on my Mac, I had to enable the Use Docker Compose V2 flag in Docker Desktop (under "Preferences -> General"). Without that checked, I got errors like this:

ERROR: for apollo-federation-subgraph-compatibility_router_1  Cannot start service router: OCI runtime create failed: container_linux.go:380: starting container process caused: process_linux.go:545: container init caused: rootfs_linux.go:76: mounting "/host_mnt/Users/myron/Development/sq-elasticgraph-ruby/elasticgraph-apollo/vendor/apollo-federation-subgraph-compatibility/supergraph.graphql" to rootfs at "/etc/config/supergraph.graphql" caused: mount through procfd: not a directory: unknown: Are you trying to mount a directory onto a file (or vice-versa)? Check if the specified host path exists and is the expected type