Logging in your Spring-boot application with LogBook

2021-03-26 Articles Renso Diaz

Logging requests and responses is easy but sometimes it turns into a complicated mess because we need to change and figure out where things are being printed or which files are doing it. So a great solution for that is Logbook, because it allows you to modify Beans with your own filters and intercept the requests and responses in one single place.

Add dependencies to the Pom.xml file:

<!-- LogBook dependency -->
<dependency>
    <groupId>org.zalando</groupId>
    <artifactId>logbook-spring-boot-starter</artifactId>
    <version>2.4.2</version>
</dependency>

Add properties to the application.properties file:

here we can set how logbook is going to behave, like what level of logging, which file to exclude or if we want to enable filters and many more:

### Logbook Configurations ###
logging.level.ROOT=INFO
logbook.filter.enabled=true
logbook.exclude=/actuator/**, /swagger-ui**, /api-docs**
logbook.format.style=json
logbook.secure-filter.enabled=true
logging.level.org.zalando.logbook=TRACE
### This property is not part of logbook but to have a cleaner support when masking 
fields we will use for our configuration ###
application.maskFields=my,field,to,mask

Note: With the above steps you can run you service endpoints and see logs coming in and out but if you want to configure logbook to your needs keep reading.

Creating configuration file:

import com.macys.enclave.rest.tracing.LogbookMasking;
import org.json.JSONException;
import org.json.JSONObject;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.zalando.logbook.BodyFilter;
import static org.zalando.logbook.BodyFilter.merge;
import static org.zalando.logbook.BodyFilters.defaultValue;

@Configuration
public class LogBookConfig extends LogbookMasking {
    private static final Logger LOGGER = LoggerFactory.getLogger(LogBookConfig.class);

    @Value("${application.maskFields}")
    private String[] propertiesToMask;

    @Bean
    public BodyFilter bodyFilter() {
        BodyFilter bodyFilter = merge(defaultValue(), maskFieldsAndObjects());
        return bodyFilter;
    }

    private BodyFilter maskFieldsAndObjects() {
        return (contentType, body) -> {
            if (body != null && body.length() > 0) {
                try {
                    JSONObject json = new JSONObject(body);
                    maskJsonObject(json, propertiesToMask);
                    return ("\n" + json + "\n");
                } catch (JSONException e) {
                    if (LOGGER.isErrorEnabled())
                        LOGGER.error("error parsing body as json to pretty-print it", e);
                }
            }
            return (body);
        };
    }
}