Add a possibility to configure CORS.

README.md

@@ -19,6 +19,10 @@ release. This directory needs to be configured in the environment variable
 git clone https://github.com/MassBank/MassBank-data.git
 export MB_DATA_DIRECTORY="./MassBank-data"
 ```
+To configure CORS you can set the environment variable `CORS_ALLOWED_ORIGINS`.
+```bash
+export CORS_ALLOWED_ORIGINS=http://localhost:3000
+```
 
 ## Build and Run
 Build the service with Maven:

src/main/java/de/ipb_halle/massbank3_export_service/api/WebConfig.java

@@ -0,0 +1,28 @@
+package de.ipb_halle.massbank3_export_service.api;
+
+import org.springframework.beans.factory.annotation.Value;
+import org.springframework.context.annotation.Bean;
+import org.springframework.context.annotation.Configuration;
+import org.springframework.lang.NonNull;
+import org.springframework.web.servlet.config.annotation.CorsRegistry;
+import org.springframework.web.servlet.config.annotation.WebMvcConfigurer;
+
+@Configuration
+public class WebConfig {
+
+    @Value("${cors.allowedOrigins:*}")
+    private String allowedOrigins;
+
+    @Bean
+    public WebMvcConfigurer corsConfigurer() {
+        return new WebMvcConfigurer() {
+            @Override
+            public void addCorsMappings(@NonNull CorsRegistry registry) {
+                registry.addMapping("/**")
+                    .allowedOrigins(allowedOrigins.split(","))
+                    .allowedMethods("GET", "POST", "PUT", "DELETE", "OPTIONS")
+                    .allowedHeaders("*");
+            }
+        };
+    }
+}