Add schema printer endpoint

This commit auto-configures a web endpoint that prints the GraphQL
schema of the application.

Closes gh-13

README.md

@@ -121,8 +121,12 @@ The Spring GraphQL project offers a few configuration properties to customize yo
 # web path to the graphql endpoint
 spring.graphql.path=/graphql
 # location of the graphql schema file
-spring.graphql.schema-location=classpath:/schema.graphqls
-# Whether micrometer metrics should be collected for graphql queries
+spring.graphql.schema.location=classpath:/schema.graphqls
+# schema printer endpoint configuration
+# endpoint path is concatenated with the main path, so "/graphql/schema" by default
+spring.graphql.schema.printer.enabled=false
+spring.graphql.schema.printer.path=/schema
+# whether micrometer metrics should be collected for graphql queries
 management.metrics.graphql.autotime.enabled=true
 ````
 

graphql-spring-boot-starter/src/main/java/org/springframework/graphql/boot/GraphQLAutoConfiguration.java

@@ -57,9 +57,7 @@ public class GraphQLAutoConfiguration {
 		public GraphQLSource.Builder graphQLSourceBuilder(
 				GraphQLProperties properties, RuntimeWiring runtimeWiring,
 				ResourceLoader resourceLoader, ObjectProvider<Instrumentation> instrumentationsProvider) {
-
-			String schemaLocation = properties.getSchemaLocation();
-
+			String schemaLocation = properties.getSchema().getLocation();
 			return GraphQLSource.builder()
 					.schemaResource(resourceLoader.getResource(schemaLocation))
 					.runtimeWiring(runtimeWiring)

graphql-spring-boot-starter/src/main/java/org/springframework/graphql/boot/GraphQLProperties.java

@@ -22,17 +22,14 @@ import org.springframework.boot.context.properties.ConfigurationProperties;
 @ConfigurationProperties(prefix = "spring.graphql")
 public class GraphQLProperties {
 
-	/**
-	 * Location of the GraphQL schema file.
-	 */
-	private String schemaLocation = "classpath:schema.graphqls";
-
 	/**
 	 * Path of the GraphQL HTTP query endpoint.
 	 */
 	private String path = "/graphql";
 
-	private WebSocket websocket = new WebSocket();
+	private final Schema schema = new Schema();
+
+	private final WebSocket websocket = new WebSocket();
 
 	public String getPath() {
 		return this.path;
@@ -42,19 +39,69 @@ public class GraphQLProperties {
 		this.path = path;
 	}
 
-	public String getSchemaLocation() {
-		return this.schemaLocation;
-	}
-
-	public void setSchemaLocation(String schemaLocation) {
-		this.schemaLocation = schemaLocation;
+	public Schema getSchema() {
+		return this.schema;
 	}
 
 	public WebSocket getWebsocket() {
 		return this.websocket;
 	}
 
-	static class WebSocket {
+	public static class Schema {
+
+		/**
+		 * Location of the GraphQL schema file.
+		 */
+		private String location = "classpath:schema.graphqls";
+
+		private final Printer printer = new Printer();
+
+		public String getLocation() {
+			return this.location;
+		}
+
+		public void setLocation(String location) {
+			this.location = location;
+		}
+
+		public Printer getPrinter() {
+			return this.printer;
+		}
+
+
+		public static class Printer {
+
+			/**
+			 * Whether the endpoint that prints the schema is enabled.
+			 */
+			private boolean enabled = false;
+
+			/**
+			 * Path under the main GraphQL path where the schema is exposed.
+			 */
+			private String path = "/schema";
+
+			public boolean isEnabled() {
+				return this.enabled;
+			}
+
+			public void setEnabled(boolean enabled) {
+				this.enabled = enabled;
+			}
+
+			public String getPath() {
+				return this.path;
+			}
+
+			public void setPath(String path) {
+				this.path = path;
+			}
+		}
+
+	}
+
+
+	public static class WebSocket {
 
 		/**
 		 * Path of the GraphQL WebSocket subscription endpoint.

graphql-spring-boot-starter/src/main/java/org/springframework/graphql/boot/WebFluxGraphQLAutoConfiguration.java

@@ -19,6 +19,7 @@ import java.util.Collections;
 import java.util.stream.Collectors;
 
 import graphql.GraphQL;
+import graphql.schema.idl.SchemaPrinter;
 import org.apache.commons.logging.Log;
 import org.apache.commons.logging.LogFactory;
 import reactor.core.publisher.Mono;
@@ -75,20 +76,23 @@ public class WebFluxGraphQLAutoConfiguration {
 	}
 
 	@Bean
-	public RouterFunction<ServerResponse> graphQLEndpoint(
-			GraphQLHttpHandler handler, GraphQLProperties properties, ResourceLoader resourceLoader) {
+	public RouterFunction<ServerResponse> graphQLEndpoint(GraphQLHttpHandler handler, GraphQLSource graphQLSource,
+			GraphQLProperties properties, ResourceLoader resourceLoader) {
 
 		String path = properties.getPath();
 		Resource resource = resourceLoader.getResource("classpath:graphiql/index.html");
-
 		if (logger.isInfoEnabled()) {
 			logger.info("GraphQL endpoint HTTP POST " + path);
 		}
-
-		return RouterFunctions.route()
+		RouterFunctions.Builder builder = RouterFunctions.route()
 				.GET(path, req -> ServerResponse.ok().bodyValue(resource))
-				.POST(path, accept(MediaType.APPLICATION_JSON).and(contentType(MediaType.APPLICATION_JSON)), handler::handleQuery)
-				.build();
+				.POST(path, accept(MediaType.APPLICATION_JSON).and(contentType(MediaType.APPLICATION_JSON)), handler::handleQuery);
+		if (properties.getSchema().getPrinter().isEnabled()) {
+			SchemaPrinter schemaPrinter = new SchemaPrinter();
+			builder = builder.GET(path + properties.getSchema().getPrinter().getPath(),
+					req -> ServerResponse.ok().contentType(MediaType.TEXT_PLAIN).bodyValue(schemaPrinter.print(graphQLSource.schema())));
+		}
+		return builder.build();
 	}
 
 	@ConditionalOnProperty(prefix = "spring.graphql.websocket", name = "path")

graphql-spring-boot-starter/src/main/java/org/springframework/graphql/boot/WebMvcGraphQLAutoConfiguration.java

@@ -23,6 +23,7 @@ import javax.servlet.http.HttpServletRequest;
 import javax.websocket.server.ServerContainer;
 
 import graphql.GraphQL;
+import graphql.schema.idl.SchemaPrinter;
 import org.apache.commons.logging.Log;
 import org.apache.commons.logging.LogFactory;
 
@@ -82,20 +83,23 @@ public class WebMvcGraphQLAutoConfiguration {
 	}
 
 	@Bean
-	public RouterFunction<ServerResponse> graphQLQueryEndpoint(
-			ResourceLoader resourceLoader, GraphQLHttpHandler handler, GraphQLProperties properties) {
+	public RouterFunction<ServerResponse> graphQLQueryEndpoint(GraphQLHttpHandler handler, GraphQLSource graphQLSource,
+			GraphQLProperties properties, ResourceLoader resourceLoader) {
 
 		String path = properties.getPath();
 		Resource resource = resourceLoader.getResource("classpath:graphiql/index.html");
-
 		if (logger.isInfoEnabled()) {
 			logger.info("GraphQL endpoint HTTP POST " + path);
 		}
-
-		return RouterFunctions.route()
+		RouterFunctions.Builder builder = RouterFunctions.route()
 				.GET(path, req -> ServerResponse.ok().body(resource))
-				.POST(path, contentType(MediaType.APPLICATION_JSON).and(accept(MediaType.APPLICATION_JSON)), handler::handle)
-				.build();
+				.POST(path, contentType(MediaType.APPLICATION_JSON).and(accept(MediaType.APPLICATION_JSON)), handler::handle);
+		if (properties.getSchema().getPrinter().isEnabled()) {
+			SchemaPrinter schemaPrinter = new SchemaPrinter();
+			builder = builder.GET(path + properties.getSchema().getPrinter().getPath(),
+					req -> ServerResponse.ok().contentType(MediaType.TEXT_PLAIN).body(schemaPrinter.print(graphQLSource.schema())));
+		}
+		return builder.build();
 	}
 
 

graphql-spring-boot-starter/src/test/java/org/springframework/graphql/boot/GraphQLAutoConfigurationTests.java

@@ -47,14 +47,14 @@ class GraphQLAutoConfigurationTests {
 	@Test
 	void shouldCreateBuilderWithSdl() {
 		contextRunner
-				.withPropertyValues("spring.graphql.schema-location:classpath:books/schema.graphqls")
+				.withPropertyValues("spring.graphql.schema.location:classpath:books/schema.graphqls")
 				.run((context) -> assertThat(context).hasSingleBean(GraphQLSource.class));
 	}
 
 	@Test
 	void shouldUseProgrammaticallyDefinedBuilder() {
 		contextRunner
-				.withPropertyValues("spring.graphql.schema-location:classpath:books/schema.graphqls")
+				.withPropertyValues("spring.graphql.schema.location:classpath:books/schema.graphqls")
 				.withUserConfiguration(CustomGraphQLBuilderConfiguration.class)
 				.run((context) -> {
 					assertThat(context).hasBean("customGraphQLSourceBuilder");

graphql-spring-boot-starter/src/test/java/org/springframework/graphql/boot/WebFluxApplicationContextTests.java

@@ -18,6 +18,7 @@ package org.springframework.graphql.boot;
 import java.util.Collections;
 import java.util.function.Consumer;
 
+import org.hamcrest.Matchers;
 import org.junit.jupiter.api.Test;
 
 import org.springframework.boot.autoconfigure.AutoConfigurations;
@@ -97,6 +98,16 @@ class WebFluxApplicationContextTests {
 		});
 	}
 
+	@Test
+	void schemaEndpoint() {
+		testWithWebClient(client -> {
+			client.get().uri("/schema").accept(MediaType.ALL).exchange()
+					.expectStatus().isOk()
+					.expectHeader().contentType(MediaType.TEXT_PLAIN)
+					.expectBody(String.class).value(Matchers.containsString("type Book"));
+		});
+	}
+
 	private void testWithWebClient(Consumer<WebTestClient> consumer) {
 		testWithApplicationContext(context -> {
 			WebTestClient client = WebTestClient.bindToApplicationContext(context)
@@ -117,7 +128,8 @@ class WebFluxApplicationContextTests {
 				.withUserConfiguration(DataFetchersConfiguration.class, CustomWebInterceptor.class)
 				.withPropertyValues(
 						"spring.main.web-application-type=reactive",
-						"spring.graphql.schema-location:classpath:books/schema.graphqls")
+						"spring.graphql.schema.printer.enabled=true",
+						"spring.graphql.schema.location=classpath:books/schema.graphqls")
 				.run(consumer);
 	}
 

graphql-spring-boot-starter/src/test/java/org/springframework/graphql/boot/WebMvcApplicationContextTests.java

@@ -17,6 +17,7 @@
 package org.springframework.graphql.boot;
 
 
+import org.hamcrest.Matchers;
 import org.junit.jupiter.api.Test;
 
 import org.springframework.boot.autoconfigure.AutoConfigurations;
@@ -32,10 +33,12 @@ import org.springframework.http.MediaType;
 import org.springframework.test.web.servlet.MockMvc;
 import org.springframework.test.web.servlet.MvcResult;
 import org.springframework.test.web.servlet.request.MockHttpServletRequestBuilder;
+import org.springframework.test.web.servlet.result.MockMvcResultMatchers;
 import org.springframework.test.web.servlet.setup.MockMvcBuilders;
 
 import static graphql.schema.idl.TypeRuntimeWiring.newTypeWiring;
 import static org.springframework.test.web.servlet.request.MockMvcRequestBuilders.asyncDispatch;
+import static org.springframework.test.web.servlet.request.MockMvcRequestBuilders.get;
 import static org.springframework.test.web.servlet.request.MockMvcRequestBuilders.post;
 import static org.springframework.test.web.servlet.result.MockMvcResultMatchers.content;
 import static org.springframework.test.web.servlet.result.MockMvcResultMatchers.header;
@@ -97,13 +100,23 @@ class WebMvcApplicationContextTests {
 		});
 	}
 
+	@Test
+	void schemaEndpoint() {
+		testWith(mockMvc -> {
+			mockMvc.perform(get("/graphql/schema")).andExpect(status().isOk())
+					.andExpect(content().contentType(MediaType.TEXT_PLAIN))
+					.andExpect(content().string(Matchers.containsString("type Book")));
+		});
+	}
+
 	private void testWith(MockMvcConsumer mockMvcConsumer) {
 		new WebApplicationContextRunner()
 				.withConfiguration(AUTO_CONFIGURATIONS)
 				.withUserConfiguration(DataFetchersConfiguration.class, CustomWebInterceptor.class)
 				.withPropertyValues(
 						"spring.main.web-application-type=servlet",
-						"spring.graphql.schema-location:classpath:books/schema.graphqls")
+						"spring.graphql.schema.printer.enabled=true",
+						"spring.graphql.schema.location=classpath:books/schema.graphqls")
 				.run((context) -> {
 					MockHttpServletRequestBuilder builder = post("/graphql")
 							.contentType(MediaType.APPLICATION_JSON)

samples/webmvc-http/src/main/resources/application.properties

@@ -1 +1,3 @@
-management.endpoints.web.exposure.include=health,metrics,info
+management.endpoints.web.exposure.include=health,metrics,info
+
+spring.graphql.schema.printer.enabled=true

spring-graphql/src/main/java/org/springframework/graphql/support/DefaultGraphQLSourceBuilder.java

@@ -107,7 +107,7 @@ class DefaultGraphQLSourceBuilder implements GraphQLSource.Builder {
 		this.graphQLConfigurers.accept(builder);
 		GraphQL graphQL = builder.build();
 
-		return new CachedGraphQLSource(graphQL);
+		return new CachedGraphQLSource(graphQL, schema);
 	}
 
 	private TypeDefinitionRegistry parseSchemaResource() {
@@ -126,20 +126,28 @@ class DefaultGraphQLSourceBuilder implements GraphQLSource.Builder {
 
 
 	/**
-	 * GraphQLSource that returns the built GraphQL instance.
+	 * GraphQLSource that returns the built GraphQL instance and its schema.
 	 */
 	private static class CachedGraphQLSource implements GraphQLSource {
 
 		private final GraphQL graphQL;
 
-		CachedGraphQLSource(GraphQL graphQL) {
+		private final GraphQLSchema schema;
+
+		CachedGraphQLSource(GraphQL graphQL, GraphQLSchema schema) {
 			this.graphQL = graphQL;
+			this.schema = schema;
 		}
 
 		@Override
 		public GraphQL graphQL() {
 			return this.graphQL;
 		}
+
+		@Override
+		public GraphQLSchema schema() {
+			return this.schema;
+		}
 	}
 
 }

spring-graphql/src/main/java/org/springframework/graphql/support/GraphQLSource.java

@@ -45,6 +45,11 @@ public interface GraphQLSource {
 	 */
 	GraphQL graphQL();
 
+	/**
+	 * Return the {@link GraphQLSchema} used by the current {@link GraphQL}.
+	 */
+	GraphQLSchema schema();
+
 
 	/**
 	 * Return a builder for a {@link GraphQLSource} given input for the