I have a Karaf (v4.2.15) application using the default PAX logging with associated config file org.ops4j.pax.logging.cfg. I am trying to update my graylog appender from log4j v1, in an older version of the application, to the current log4j2 implementation.
I have replaced the old gelf library (org.graylog2/gelfj) with the recommended biz.paluch.logging/logstash-gelf. I have had to wrapped it as an OSGI bundle making sure the biz.paluch.logging.gelf.log4j2 package is exported and that the Log4j2Plugins.dat file is included. Here is the pom.xml.
<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
<modelVersion>4.0.0</modelVersion>
<groupId>osgi.biz.paluch.logging</groupId>
<artifactId>logstash-gelf</artifactId>
<version>1.15.0</version>
<packaging>bundle</packaging>
<name>logstash-gelf OSGi Bundle</name>
<description>This OSGi bundle simply wraps logstash-gelf-1.15.0jar artifact.</description>
<dependencies>
<dependency>
<groupId>biz.paluch.logging</groupId>
<artifactId>logstash-gelf</artifactId>
<version>1.15.0</version>
</dependency>
</dependencies>
<build>
<defaultGoal>install</defaultGoal>
<plugins>
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-shade-plugin</artifactId>
<version>3.3.0</version>
<executions>
<execution>
<phase>package</phase>
<goals>
<goal>shade</goal>
</goals>
<configuration>
<artifactSet>
<includes>
<include>biz.paluch.logging:logstash-gelf</include>
</includes>
</artifactSet>
<filters>
<filter>
<includes>
<include>META-INF/org/apache/logging/log4j/core/config/plugins/Log4j2Plugins.dat</include>
</includes>
</filter>
</filters>
</configuration>
</execution>
</executions>
</plugin>
<plugin>
<groupId>org.apache.felix</groupId>
<artifactId>maven-bundle-plugin</artifactId>
<version>5.1.2</version>
<extensions>true</extensions>
<configuration>
<instructions>
<Bundle-SymbolicName>${project.artifactId}</Bundle-SymbolicName>
<Export-Package>biz.paluch.logging.gelf.log4j2</Export-Package>
<_versionpolicy>[$(version;==;$(@)),$(version;+;$(@)))</_versionpolicy>
<_removeheaders>Ignore-Package,Include-Resource,Private-Package,Embed-Dependency</_removeheaders>
</instructions>
</configuration>
</plugin>
</plugins>
</build>
</project>
I've then added it to the karaf startup.properties as I had done with gelfj so that it can log the application startup.
# Bundles to be started on startup, with startlevel
mvn\:org.apache.karaf.features/org.apache.karaf.features.extension/4.2.15 = 1
mvn\:org.ops4j.pax.url/pax-url-aether/2.6.7 = 5
mvn\:org.ops4j.pax.logging/pax-logging-log4j2/1.11.13 = 8
mvn\:org.ops4j.pax.logging/pax-logging-api/1.11.13 = 8
mvn\:org.fusesource.jansi/jansi/1.18 = 8
mvn\:org.osgi/org.osgi.util.promise/1.1.1 = 9
mvn\:org.apache.felix/org.apache.felix.coordinator/1.0.2 = 9
mvn\:org.osgi/org.osgi.util.function/1.1.0 = 9
mvn\:org.apache.felix/org.apache.felix.configadmin/1.9.22 = 10
mvn\:org.apache.felix/org.apache.felix.fileinstall/3.7.4 = 11
mvn\:org.apache.karaf.features/org.apache.karaf.features.core/4.2.15 = 15
# My bundles
mvn\:osgi.biz.paluch.logging/logstash-gelf/1.15.0 = 7`
I've confirmed it is installed:
START LEVEL 100 , List Threshold: 0
ID │ State │ Lvl │ Version │ Name
────┼──────────┼─────┼────────────────────────────┼───────
0 │ Active │ 0 │ 5.6.12 │ System Bundle, Fragments: 1
1 │ Resolved │ 1 │ 4.2.15 │ Apache Karaf :: Features :: Extension, Hosts: 0
2 │ Active │ 5 │ 2.6.7 │ OPS4J Pax Url - mvn:
3 │ Active │ 8 │ 1.11.13 │ OPS4J Pax Logging - Log4Jv2 implementation
4 │ Active │ 8 │ 1.11.13 │ OPS4J Pax Logging - API
5 │ Active │ 8 │ 1.18.0 │ jansi
6 │ Active │ 9 │ 1.1.1.201810101357 │ org.osgi:org.osgi.util.promise
7 │ Active │ 9 │ 1.0.2 │ Apache Felix Coordinator Service
8 │ Active │ 9 │ 1.1.0.201802012106 │ org.osgi:org.osgi.util.function
9 │ Active │ 10 │ 1.9.22 │ Apache Felix Configuration Admin Service
10 │ Active │ 11 │ 3.7.4 │ Apache Felix File Install
11 │ Active │ 15 │ 4.2.15 │ Apache Karaf :: Features :: Core
12 │ Active │ 7 │ 1.15.0 │ logstash-gelf OSGi Bundle
My understanding is that log4j2 use a bundleListner to look for plugins and so should automatically find the "Gelf" plugin. I've configured the appender as:
log4j2.appender.graylog.type = Gelf
log4j2.appender.graylog.name = Graylog
log4j2.appender.graylog.host = log.server.com
log4j2.appender.graylog.port = 12201
log4j2.appender.graylog.originHost = myapp.server.com
Unfortunately I just get an error that the Gelf plugin can't be found, this occurs whether the config is present at startup or loaded dynamically after pax logging has initialized
org.ops4j.pax.logging.pax-logging-log4j2 [log4j2] ERROR : Unable to locate plugin type for Gelf Ignored FQCN: org.apache.logging.log4j.spi.AbstractLogger
In case the BundleListener is not working I've tried declaring the package both in the config log4j2.packages = biz.paluch.logging.gelf.log4j2 and also on the commandline -Dlogj4.plugin.packages=biz.paluch.logging.gelf.log4j2
Any solutions or suggestions how to debug why the log4j2/pax can't find the Gelf plugin gratefully received.
After following the rabbit hole of GELF appender plugins I went back a looked through the the log4j2 document. I found that there is inbuilt support for the GELF layout and that you can use the Socket appender to direct logs to your Graylog server. This is a far cleaner way to achieve logging from startup and it works!
As far as I can tell it provides parity with the functionality I had before and appears to render logstash-gelf's log4j2 support unnecessary. Please comment if you know otherwise. Here is a example with additional fields:
# Socket GELF/Graylog Appender
log4j2.rootLogger.appenderRef.Graylog.ref = Graylog
log4j2.appender.graylog.type = Socket
log4j2.appender.graylog.name = Graylog
log4j2.appender.graylog.host = graylog.server.com
log4j2.appender.graylog.port = 12201
log4j2.appender.graylog.protocol = UDP
log4j2.appender.graylog.immediateFail = true
log4j2.appender.graylog.layout.type = GelfLayout
log4j2.appender.graylog.layout.host = my.server.com
log4j2.appender.graylog.layout.includeStacktrace = true
log4j2.appender.graylog.layout.additionalField1.type = KeyValuePair
log4j2.appender.graylog.layout.additionalField1.key = environment
log4j2.appender.graylog.layout.additionalField1.value = test