Remove the internal schema as a package level var to fix race issues (#148)

This triggers the Go race detector when using the gateway in tests.

There is very little advantage to having the package level var.

Author: rleavengood-scwx

gateway.go

@@ -106,9 +106,20 @@ func (g *Gateway) Execute(ctx *RequestContext, plans QueryPlanList) (map[string]
 	return result, nil
 }
 
-func (g *Gateway) internalSchema() *ast.Schema {
+func (g *Gateway) internalSchema() (*ast.Schema, error) {
 	// we start off with the internal schema
-	schema := internalSchema
+	schema, err := graphql.LoadSchema(`
+		interface Node {
+			id: ID!
+		}
+
+		type Query {
+			node(id: ID!): Node
+		}
+	`)
+	if schema == nil {
+		return nil, fmt.Errorf("Syntax error in schema string: %s", err.Error())
+	}
 
 	// then we have to add any query fields we have
 	for _, field := range g.queryFields {
@@ -120,7 +131,7 @@ func (g *Gateway) internalSchema() *ast.Schema {
 	}
 
 	// we're done
-	return schema
+	return schema, nil
 }
 
 // New instantiates a new schema with the required stuffs.
@@ -161,7 +172,10 @@ func New(sources []*graphql.RemoteSchema, configs ...Option) (*Gateway, error) {
 		}
 	}
 
-	internal := gateway.internalSchema()
+	internal, err := gateway.internalSchema()
+	if err != nil {
+		return nil, err
+	}
 	// find the field URLs before we merge schemas. We need to make sure to include
 	// the fields defined by the gateway's internal schema
 	urls := fieldURLs(sources, true).Concat(

internal.go

@@ -2,7 +2,6 @@ package gateway
 
 import (
 	"context"
-	"fmt"
 
 	"github.com/99designs/gqlgen/graphql/introspection"
 	"github.com/mitchellh/mapstructure"
@@ -11,10 +10,6 @@ import (
 	"github.com/nautilus/graphql"
 )
 
-// internalSchema is a graphql schema that exists at the gateway level and is merged with the
-// other schemas that the gateway wraps.
-var internalSchema *ast.Schema
-
 // internalSchemaLocation is the location that functions should take to identify a remote schema
 // that points to the gateway's internal schema.
 const internalSchemaLocation = "🎉"
@@ -310,21 +305,3 @@ func (g *Gateway) introspectDirectiveSlice(directives []introspection.Directive,
 
 	return result
 }
-
-func init() {
-	// load the internal
-	schema, err := graphql.LoadSchema(`
-		interface Node {
-			id: ID!
-		}
-
-		type Query {
-			node(id: ID!): Node
-		}
-	`)
-	if schema == nil {
-		panic(fmt.Sprintf("Syntax error in schema string: %s", err.Error()))
-	}
-
-	internalSchema = schema
-}