Configuring Logging
Hazelcast has a flexible logging configuration and does not depend on any logging framework except JDK logging. It has built-in adapters for a number of logging frameworks and it also supports custom loggers by providing logging interfaces.
Logging for Member
By default, a Hazelcast member writes logs into the logs
directory of the
distribution. The logs are configured to roll over daily. You can change
the logging configuration by modifying config/log4j.properties
.
To use the built-in adapters, set the hazelcast.logging.type
property
to one of the predefined types below:
-
jdk: JDK logging (default)
-
log4j: Log4j
-
log4j2: Log4j2
-
slf4j: Slf4j
-
none: disable logging
You can set hazelcast.logging.type
through declarative configuration,
programmatic configuration or JVM system property.
If you choose to use log4j , log4j2 , or slf4j , you should include
the proper dependencies in the classpath.
|
Declarative Configuration:
Config config = new Config() ; config.setProperty( "hazelcast.logging.type", "log4j2" );
Logging Pattern
The default log output resembles the following example:
2022-02-16 11:40:52,463 [ INFO] [main] [c.h.system]: [172.18.0.2]:5701 [hello-world] [5.0.5] Copyright (c) 2008-2022, Hazelcast, Inc. All Rights Reserved.
2022-02-16 11:40:52,463 [ INFO] [main] [c.h.system]: [172.18.0.2]:5701 [hello-world] [5.0.5] Hazelcast Platform 5.0.5 (20220210 - 1d718cf) starting at [172.18.0.2]:5701
2022-02-16 11:40:52,463 [ INFO] [main] [c.h.system]: [172.18.0.2]:5701 [hello-world] [5.0.5] Cluster name: hello-world
The logging pattern is shown below.
You can customize the default logging pattern using the LOGGING_PATTERN
environment variable while starting a member.
Here is an example usage.
- CLI
- Docker
You can also provide a properties file having a path of your choice. For Log4j2, you can specify this using the following JVM argument (which is the only way for Log4j2).
== Modifying the Default Logging
If you do not need detailed logs, the default settings are enough. Using the Hazelcast specific lines in the default configuration file, you can select to see specific logs (cluster, partition, hibernate, etc.) in desired levels:
To enable the debug logs for all Hazelcast operations, uncomment the below line in the configuration file:
You can also use the hazelcast.logging.details.enabled
property to
specify whether the name, IP address and version of the cluster are included
in the logs. When there are lots of log lines, it may be hard to follow.
When set to false
, those information will not appear.
== Using JSON Template
You can use JSON templates for the member log files.
The JSON logging configuration file built on the default JSON template layout is <HAZELCAST HOME>/config/log4j2-json.properties
.
You can use a different JSON template via the LOGGING_JSON_TEMPLATE
environment variable. Here is an example usage.
- CLI
- Docker
Programmatic Configuration
System Property
-
using the
java -Dhazelcast.logging.type=slf4j
JVM parameter -
using the
System.setProperty( "hazelcast.logging.type", "none" );
system class
Logging for Client and Embedded Mode
When using Hazelcast through the client or in embedded mode, Hazelcast doesn’t automatically add any dependencies to any logging framework and allows configuration of which facade the logging should be done through.
To configure the logging facade to use, you need to set a property in the configuration file:
Alternatively, you can use the system property
-Dhazelcast.logging.type
to configure the logging framework to use.
Using a Custom Logger
If the provided logging mechanisms are not satisfactory, you can implement
your own using the custom logging feature. To use it, implement the
com.hazelcast.logging.LoggerFactory
and com.hazelcast.logging.ILogger
interfaces and set the system property hazelcast.logging.class
as your
custom LoggerFactory
class name.
Listening to Logging Events
You can also listen to logging events generated by Hazelcast runtime
by registering LogListener
s to LoggingService
.
Through the LoggingService
, you can get the currently used
ILogger implementation and log your own messages too.
If you are not using command line for configuring logging, you should be careful
about Hazelcast classes. They may be defaulted to jdk logging before newly configured
logging is read. When logging mechanism is selected, it will not change.
|