如何在GCP Felexible非兼容App Engine中将Java应用日志事件映射到相应的云日志事件级别？

Question

我是GCP
AppEngine的新手，出于多种原因，我选择了Flexible环境。但是，我震惊地发现灵活环境的非“兼容”运行时似乎不允许我将应用程序的日志记录事件映射到云日志记录中的适当日志记录
级别 。我阅读正确吗？
https://cloud.google.com/appengine/docs/flexible/java/writing-application-
logs#writing_application_logs_1

而且此页面确实没有帮助。https://cloud.google.com/java/getting-started/logging-
application-events

这是在阅读了GAE日志记录问题并尝试确定哪种方法适用于标准环境与灵活方法之后的数小时。据我所知，在标准环境中可以进行事件级别映射。

但是，为了对Cloud Platform
Console中的日志级别显示进行更细粒度的控制，日志记录框架必须使用java.util.logging适配器。https://cloud.google.com/appengine/docs/java/how-
requests-are-
handled#Java_Logging

好。那是一个模糊的参考，但是我认为我在其他地方看到了一些更清楚的东西。

无论如何，在“灵活”的环境中这难道不是很容易吗？谁不想通过记录级别轻松过滤事件？

更新： 我澄清了这个问题，以表明我要问的是GAE flexible环境中的不兼容运行时。

Answer 1

这是我如何使用SLF4J使云日志记录工作。这适用于不兼容的Java GAE Flex环境。

logback.xml

<configuration debug="true">
    <appender name="FILE" class="ch.qos.logback.core.FileAppender">
        <file>/var/log/app_engine/custom_logs/app.log.json</file>
        <append>true</append>
        <!-- encoders are assigned the type ch.qos.logback.classic.encoder.PatternLayoutEncoder by default -->
        <encoder class="ch.qos.logback.core.encoder.LayoutWrappingEncoder">
            <layout
                class="putyourpackagenamehere.GCPCloudLoggingJSONLayout">
                <pattern>%-4relative [%thread] %-5level %logger{35} - %msg</pattern>
            </layout>
        </encoder>
    </appender>
    <root level="DEBUG">
        <appender-ref ref="FILE" />
    </root>
</configuration>

这是我用来在日志文件中的一行上生成JSON的PatternLayout类。

import static ch.qos.logback.classic.Level.DEBUG_INT;
import static ch.qos.logback.classic.Level.ERROR_INT;
import static ch.qos.logback.classic.Level.INFO_INT;
import static ch.qos.logback.classic.Level.TRACE_INT;
import static ch.qos.logback.classic.Level.WARN_INT;

import java.util.Map;

import org.json.JSONObject;

import com.homedepot.ta.wh.common.logging.GCPCloudLoggingJSONLayout.GCPCloudLoggingEvent.GCPCloudLoggingTimestamp;

import ch.qos.logback.classic.Level;
import ch.qos.logback.classic.PatternLayout;
import ch.qos.logback.classic.spi.ILoggingEvent;

/**
 * Format a LoggingEvent as a single line JSON object  
 * 
 *  <br>https://cloud.google.com/appengine/docs/flexible/java/writing-application-logs
 *  
 *  <br>From https://cloud.google.com/appengine/articles/logging
 *  <quote>
 *  Applications using the flexible environment should write custom log files to the VM's log directory at 
 *  /var/log/app_engine/custom_logs. These files are automatically collected and made available in the Logs Viewer. 
 *  Custom log files must have the suffix .log or .log.json. If the suffix is .log.json, the logs must be in JSON 
 *  format with one JSON object per line. If the suffix is .log, log entries are treated as plain text.
 *  </quote>
 *  
 *  Nathan: I can't find a reference to this format on the google pages but I do remember getting the format from some
 *  GO code that a googler on the community slack channel referred me to.   
 */
public class GCPCloudLoggingJSONLayout extends PatternLayout {

    @Override
    public String doLayout(ILoggingEvent event) {
        String formattedMessage = super.doLayout(event);
        return doLayout_internal(formattedMessage, event);
    }

    /* for testing without having to deal wth the complexity of super.doLayout() 
     * Uses formattedMessage instead of event.getMessage() */
    String doLayout_internal(String formattedMessage, ILoggingEvent event) {
        GCPCloudLoggingEvent gcpLogEvent = new GCPCloudLoggingEvent(formattedMessage
                                                                    , convertTimestampToGCPLogTimestamp(event.getTimeStamp())
                                                                    , mapLevelToGCPLevel(event.getLevel())
                                                                    , null);
        JSONObject jsonObj = new JSONObject(gcpLogEvent);
        /* Add a newline so that each JSON log entry is on its own line.
         * Note that it is also important that the JSON log entry does not span multiple lines.
         */
        return jsonObj.toString() + "\n"; 
    }

    static GCPCloudLoggingTimestamp convertTimestampToGCPLogTimestamp(long millisSinceEpoch) {
        int nanos = ((int) (millisSinceEpoch % 1000)) * 1_000_000; // strip out just the milliseconds and convert to nanoseconds
        long seconds = millisSinceEpoch / 1000L; // remove the milliseconds
        return new GCPCloudLoggingTimestamp(seconds, nanos);
    }

    static String mapLevelToGCPLevel(Level level) {
        switch (level.toInt()) {
        case TRACE_INT:
            return "TRACE";
        case DEBUG_INT:
            return "DEBUG";
        case INFO_INT:
            return "INFO";
        case WARN_INT:
            return "WARN";
        case ERROR_INT:
            return "ERROR";
        default:
            return null; /* This should map to no level in GCP Cloud Logging */
        }
    }

    /* Must be public for JSON marshalling logic */
    public static class GCPCloudLoggingEvent {
        private String message;
        private GCPCloudLoggingTimestamp timestamp;
        private String traceId;
        private String severity;

        public GCPCloudLoggingEvent(String message, GCPCloudLoggingTimestamp timestamp, String severity,
                String traceId) {
            super();
            this.message = message;
            this.timestamp = timestamp;
            this.traceId = traceId;
            this.severity = severity;
        }

        public String getMessage() {
            return message;
        }

        public void setMessage(String message) {
            this.message = message;
        }

        public GCPCloudLoggingTimestamp getTimestamp() {
            return timestamp;
        }

        public void setTimestamp(GCPCloudLoggingTimestamp timestamp) {
            this.timestamp = timestamp;
        }

        public String getTraceId() {
            return traceId;
        }

        public void setTraceId(String traceId) {
            this.traceId = traceId;
        }

        public String getSeverity() {
            return severity;
        }

        public void setSeverity(String severity) {
            this.severity = severity;
        }

        /* Must be public for JSON marshalling logic */
        public static class GCPCloudLoggingTimestamp {
            private long seconds;
            private int nanos;

            public GCPCloudLoggingTimestamp(long seconds, int nanos) {
                super();
                this.seconds = seconds;
                this.nanos = nanos;
            }

            public long getSeconds() {
                return seconds;
            }

            public void setSeconds(long seconds) {
                this.seconds = seconds;
            }

            public int getNanos() {
                return nanos;
            }

            public void setNanos(int nanos) {
                this.nanos = nanos;
            }

        }       
    }

    @Override
    public Map<String, String> getDefaultConverterMap() {
        return PatternLayout.defaultConverterMap;
    }   
}