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.

Dependency Diagram

graph LR; classDef targetGemStyle fill:#FADBD8,stroke:#EC7063,color:#000,stroke-width:2px; classDef otherEgGemStyle fill:#A9DFBF,stroke:#2ECC71,color:#000; classDef externalGemStyle fill:#E0EFFF,stroke:#70A1D7,color:#2980B9; elasticgraph-apollo["elasticgraph-apollo"]; class elasticgraph-apollo targetGemStyle; elasticgraph-graphql["elasticgraph-graphql"]; elasticgraph-apollo --> elasticgraph-graphql; class elasticgraph-graphql otherEgGemStyle; elasticgraph-support["elasticgraph-support"]; elasticgraph-apollo --> elasticgraph-support; class elasticgraph-support otherEgGemStyle; graphql["graphql"]; elasticgraph-apollo --> graphql; class graphql externalGemStyle; apollo-federation["apollo-federation"]; elasticgraph-apollo --> apollo-federation; class apollo-federation externalGemStyle; click graphql href "https://rubygems.org/gems/graphql" "Open on RubyGems.org" _blank; click apollo-federation href "https://rubygems.org/gems/apollo-federation" "Open on RubyGems.org" _blank;

Usage

First, add elasticgraph-apollo to your Gemfile, alongside the other ElasticGraph gems:

diff --git a/Gemfile b/Gemfile
index 4a5ef1e..5c16c2b 100644
--- a/Gemfile
+++ b/Gemfile
@@ -8,6 +8,7 @@ gem "elasticgraph-query_registry", *elasticgraph_details

 # Can be elasticgraph-elasticsearch or elasticgraph-opensearch based on the datastore you want to use.
 gem "elasticgraph-opensearch", *elasticgraph_details
+gem "elasticgraph-apollo", *elasticgraph_details

 gem "httpx", "~> 1.3"

Finally, update Rakefile so that ElasticGraph::GraphQL::Apollo::SchemaDefinition::APIExtension is used as one of the extension_modules:

diff --git a/Rakefile b/Rakefile
index 2943335..26633c3 100644
--- a/Rakefile
+++ b/Rakefile
@@ -1,5 +1,6 @@
 project_root = File.expand_path(__dir__)

+require "elastic_graph/apollo/schema_definition/api_extension"
 require "elastic_graph/local/rake_tasks"
 require "elastic_graph/query_registry/rake_tasks"
 require "rspec/core/rake_task"
@@ -12,6 +13,8 @@ ElasticGraph::Local::RakeTasks.new(
   local_config_yaml: settings_file,
   path_to_schema: "#{project_root}/config/schema.rb"
 ) do |tasks|
+  tasks.schema_definition_extension_modules = [ElasticGraph::Apollo::SchemaDefinition::APIExtension]
+
   # Set this to true once you're beyond the prototyping stage.
   tasks.enforce_json_schema_version = false

That's it!

Federation Version Support

This library supports multiple versions of Apollo federation. The latest release 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:

diff --git a/config/schema.rb b/config/schema.rb
index 015c5fa..362cdcb 100644
--- a/config/schema.rb
+++ b/config/schema.rb
@@ -4,6 +4,8 @@ ElasticGraph.define_schema do |schema|
   # ElasticGraph will tell you when you need to bump this.
   schema.json_schema_version 1

+  schema.target_apollo_federation_version "2.3"
+
   # This registers the elasticgraph-query_registry extension, which can be used to reject queries that
   # clients have not registered (and to reject queries that differ from what a client has registered).
   # In addition, every registered query is validated against the schema in the CI build, giving you