Notes on using Loki with URLFrontier

Loki is a log aggregation framework which integrates with Grafana.

Standalone mode

When launching URLFrontier directly as a Java process, it should be possible to use the loki-logback-appender. The URLFrontier service already uses Logback. You need to build the service from source with mvn clean package having added the loki-logback-appender Maven dependencies.

For Java 8

<dependency>
    <groupId>com.github.loki4j</groupId>
    <artifactId>loki-logback-appender-jdk8</artifactId>
    <version>1.3.2</version>
</dependency>
<dependency>
    <groupId>org.apache.httpcomponents</groupId>
    <artifactId>httpclient</artifactId>
    <version>4.5.13</version>
</dependency>

For Java 11+

<dependency>
    <groupId>com.github.loki4j</groupId>
    <artifactId>loki-logback-appender</artifactId>
    <version>1.3.2</version>
</dependency>

A configuration file can then be specified in the command line as explained in logging-configuration.

For Java 8

<appender name="LOKI" class="com.github.loki4j.logback.Loki4jAppender">
    <http class="com.github.loki4j.logback.ApacheHttpSender">
        <url>http://localhost:3100/loki/api/v1/push</url>
    </http>
    <format>
        <label>
            <pattern>app=my-app,host=${HOSTNAME},level=%level</pattern>
        </label>
        <message>
            <pattern>l=%level h=${HOSTNAME} c=%logger{20} t=%thread | %msg %ex</pattern>
        </message>
        <sortByTime>true</sortByTime>
    </format>
</appender>

<root level="DEBUG">
    <appender-ref ref="LOKI" />
</root>

For Java 11+

<appender name="LOKI" class="com.github.loki4j.logback.Loki4jAppender">
    <http>
        <url>http://localhost:3100/loki/api/v1/push</url>
    </http>
    <format>
        <label>
            <pattern>app=my-app,host=${HOSTNAME},level=%level</pattern>
        </label>
        <message>
            <pattern>l=%level h=${HOSTNAME} c=%logger{20} t=%thread | %msg %ex</pattern>
        </message>
        <sortByTime>true</sortByTime>
    </format>
</appender>

<root level="DEBUG">
    <appender-ref ref="LOKI" />
</root>

Docker

When running URLFrontier as a Docker container, the Loki Docker driver should be used.

See the configuration section.