Merge pull request #6330 from entur/otp2_add_schema_endpoint

Add endpoint to download Transmodel GraphQL Schema

application/src/main/java/org/opentripplanner/apis/transmodel/TransmodelAPI.java

@@ -2,9 +2,11 @@
 
 import com.fasterxml.jackson.databind.ObjectMapper;
 import graphql.schema.GraphQLSchema;
+import graphql.schema.idl.SchemaPrinter;
 import io.micrometer.core.instrument.Tag;
 import jakarta.ws.rs.BadRequestException;
 import jakarta.ws.rs.Consumes;
+import jakarta.ws.rs.GET;
 import jakarta.ws.rs.POST;
 import jakarta.ws.rs.Path;
 import jakarta.ws.rs.PathParam;
@@ -31,6 +33,15 @@
 @Produces(MediaType.APPLICATION_JSON)
 public class TransmodelAPI {
 
+  // Note, the blank line at the end is intended
+  private static final String SCHEMA_DOC_HEADER =
+    """
+# THIS IS NOT INTENDED FOR PRODUCTION USE. We recommend using the GraphQL introspection instead.
+# This is intended for the OTP Debug UI and can also be used by humans to get the schema with the
+# OTP configured default-values injected.
+
+""";
+
   private static final Logger LOG = LoggerFactory.getLogger(TransmodelAPI.class);
 
   private static GraphQLSchema schema;
@@ -138,6 +149,13 @@ public Response getGraphQL(String query, @Context HttpHeaders headers) {
     );
   }
 
+  @GET
+  @Path("schema.graphql")
+  public Response getGraphQLSchema() {
+    var text = SCHEMA_DOC_HEADER + new SchemaPrinter().print(schema);
+    return Response.ok().encoding("UTF-8").entity(text).build();
+  }
+
   private static Iterable<Tag> getTagsFromHeaders(HttpHeaders headers) {
     return tracingHeaderTags
       .stream()