How to use Stackdriver Structured Logging in App Engine Flex Java environment

Question

Google App Engine flexible environment automatically pipes stdout and stderr to Stackdriver (Google Cloud Logging). But this only supports plain text log message without any

Answer 1

You could use the Logback appender + Implement LoggingEnhacer

public class LogEnhancer implements LoggingEnhancer {


  @Override
  public void enhanceLogEntry(LogEntry.Builder logEntry) {
    // add Labels
    logEntry.addLabel("project", "conversational-services");

    // Transform textPayload to JSONPayload
    ObjectMapper mapper = new ObjectMapper();
    Builder structBuilder = Struct.newBuilder();
    String textPayload = logEntry.build().getPayload().getData().toString();
    try {
      // Validate JSON Payload
      mapper.readTree(textPayload);
      JsonFormat.parser().merge(textPayload, structBuilder);
      logEntry.setPayload(JsonPayload.of(structBuilder.build()));
    } catch (InvalidProtocolBufferException e) {
      // Error reporting an error! FML
      System.err.println(e.getMessage());
    } catch (IOException e) {
      // Do nothing (there is not a JSON Payload)
    }

  }

}

This class add labels and transform a JSON String in a JSONPayload

You need to specify the LoggingEnhacer on the logback.xml file

  

    
      INFO
    
    application.log 
    gae_app 
    
     [path_for_your_logging_enhancer_class]
    WARN