initial commit

Signed-off-by: Peter Siegmund <developer@mars3142.org>

src/main/java/dev/mars3142/fhq/Application.java

@@ -0,0 +1,13 @@
+package dev.mars3142.fhq;
+
+import org.springframework.boot.SpringApplication;
+import org.springframework.boot.autoconfigure.SpringBootApplication;
+
+@SpringBootApplication
+public class Application {
+
+  public static void main(String[] args) {
+    SpringApplication.run(Application.class, args);
+  }
+
+}

src/main/java/dev/mars3142/fhq/edge/GCPGatewayFilter.java

@@ -0,0 +1,59 @@
+package dev.mars3142.fhq.edge;
+
+import com.google.auth.oauth2.GoogleCredentials;
+import com.google.auth.oauth2.IdTokenCredentials;
+import com.google.auth.oauth2.IdTokenProvider;
+import java.io.IOException;
+import lombok.Getter;
+import lombok.Setter;
+import lombok.extern.slf4j.Slf4j;
+import lombok.val;
+import org.springframework.cloud.gateway.filter.GatewayFilter;
+import org.springframework.cloud.gateway.filter.factory.AbstractGatewayFilterFactory;
+import org.springframework.stereotype.Component;
+
+@Component
+@Slf4j
+public class GCPGatewayFilter extends AbstractGatewayFilterFactory<GCPGatewayFilter.Config> {
+
+  public GCPGatewayFilter() {
+    super(Config.class);
+  }
+
+  @Override
+  public GatewayFilter apply(Config config) {
+    return (exchange, chain) -> {
+      try {
+        val token = getAuthToken(config);
+        exchange.getRequest()
+            .mutate()
+            .header("X-Serverless-Authorization", "Bearer " + token);
+        return chain.filter(exchange);
+      } catch (Exception e) {
+        log.error("Error getting token", e);
+        throw new RuntimeException(e);
+      }
+    };
+  }
+
+  private String getAuthToken(Config config) throws IOException {
+    val credentials = GoogleCredentials.getApplicationDefault();
+    if (!(credentials instanceof IdTokenProvider)) {
+      throw new IllegalArgumentException("Credentials are not an instance of IdTokenProvider.");
+    }
+    val tokenCredential =
+        IdTokenCredentials.newBuilder()
+            .setIdTokenProvider((IdTokenProvider) credentials)
+            .setTargetAudience(config.getAudience())
+            .build();
+
+    return tokenCredential.refreshAccessToken().getTokenValue();
+  }
+
+  @Setter
+  @Getter
+  public static class Config {
+
+    private String audience;
+  }
+}