org.kiwiproject.beta.dropwizard.DefaultingFileAppenderFactory Maven / Gradle / Ivy

Go to download
package org.kiwiproject.beta.dropwizard;

import static org.apache.commons.lang3.StringUtils.isBlank;

import ch.qos.logback.classic.LoggerContext;
import ch.qos.logback.core.Appender;
import ch.qos.logback.core.rolling.RollingFileAppender;
import ch.qos.logback.core.spi.DeferredProcessingAware;
import com.fasterxml.jackson.annotation.JsonTypeName;
import com.google.common.annotations.Beta;
import io.dropwizard.logging.common.AppenderFactory;
import io.dropwizard.logging.common.DropwizardLayout;
import io.dropwizard.logging.common.FileAppenderFactory;
import io.dropwizard.logging.common.async.AsyncAppenderFactory;
import io.dropwizard.logging.common.filter.LevelFilterFactory;
import io.dropwizard.logging.common.layout.LayoutFactory;
import lombok.Getter;
import lombok.Setter;
import org.kiwiproject.jar.KiwiJars;

import java.io.File;
import java.util.Optional;
import java.util.TimeZone;

/**
 * A Dropwizard {@link AppenderFactory} implementation which extends {@link FileAppenderFactory} to provide default
 * values for the current log file name, archive log file name pattern, and log format if they are not explicitly
 * configured. Once the appender is built, these values can be retrieved from the factory instance using
 * {@link #getCurrentLogFilename()}, {@link #getArchivedLogFilenamePattern()}, and {@link #getLogFormat()}.
 * 
 * This factory provides the same properties available in {@link FileAppenderFactory} and one additional property
 * which allows you to easily use the default Dropwizard log format instead of the one provided here.
 * 

 * To use this in a Dropwizard application, the FQCN must be listed in a {@code META-INF/services/io.dropwizard.logging.common.AppenderFactory}
 * file. Dropwizard already provides this file with its own implementations (in the {@code dropwizard-logging} JAR).
 * This library also provides the same file with our implementation. These two files (and any others from other providers)
 * must all be combined so the resulting file contains all implementations. We generally use the
 * Maven Shade Plugin with the
 * ServicesResourceTransformer
 * to combine these service files.
 * 
 * Last, in the logging configuration
 * of your Dropwizard configuration file, you can add an {@code appender} of type {@code rollingWithDefaults}.
 *
 * @see AppenderFactory
 * @see FileAppenderFactory
 * @see RollingFileAppender
 */
@Beta
@Getter
@Setter
@JsonTypeName("rollingWithDefaults")
public class DefaultingFileAppenderFactory extends FileAppenderFactory {

    private static final String DEFAULT_LOG_FORMAT = "%-5level [%date] [%thread] %logger{5}: %message%n";

    /**
     * If true, uses the default Dropwizard log format provided by {@link DropwizardLayout}.
     */
    private boolean useDefaultDropwizardLogFormat;

    @Override
    public Appender build(LoggerContext context,
            String applicationName,
            LayoutFactory layoutFactory,
            LevelFilterFactory levelFilterFactory,
            AsyncAppenderFactory asyncAppenderFactory) {

        var nonNullApplicationName = Optional.ofNullable(applicationName).orElse("service");

        if (isBlank(getCurrentLogFilename())) {
            setCurrentLogFilename(filePathFor(nonNullApplicationName));
        }

        if (isBlank(getArchivedLogFilenamePattern())) {
            setArchivedLogFilenamePattern(archiveFileNamePatternFor(nonNullApplicationName));
        }

        if (isBlank(getLogFormat())) {
            var logFormat = newLogFormat(isUseDefaultDropwizardLogFormat(), getTimeZone());
            setLogFormat(logFormat);
        }

        return super.build(context, applicationName, layoutFactory, levelFilterFactory, asyncAppenderFactory);
    }

    private static String filePathFor(String applicationName) {
        return logPathFor(applicationName, ".log");
    }

    private static String archiveFileNamePatternFor(String applicationName) {
        return logPathFor(applicationName, "-%d.log.gz");
    }

    private static String logPathFor(String applicationName, String suffix) {
        var path = KiwiJars.getDirectoryPath(DefaultingFileAppenderFactory.class).orElse("./");
        return String.join(File.separator, path, applicationName) + suffix;
    }

    private static String newLogFormat(boolean useDefaultDropwizardLogFormat, TimeZone timeZone) {
        if (useDefaultDropwizardLogFormat) {
            var dropwizardLayout = new DropwizardLayout(new LoggerContext(), timeZone);
            return dropwizardLayout.getPattern();
        }

        return DEFAULT_LOG_FORMAT;
    }
}