SLF4J/LogbackでJSON形式のログ出力 ref: http://qiita.com/ephemeralsnow/items/10d362286aaa55120822

build.sbt

libraryDependencies ++= Seq(
  "org.slf4j" % "slf4j-api" % "1.7.12",
  "ch.qos.logback" % "logback-core" % "1.1.3",
  "ch.qos.logback" % "logback-classic" % "1.1.3",
  "ch.qos.logback.contrib" % "logback-json-core" % "0.1.2",
  "ch.qos.logback.contrib" % "logback-json-classic" % "0.1.2",
  "ch.qos.logback.contrib" % "logback-jackson" % "0.1.2",
  "com.fasterxml.jackson.core" % "jackson-core" % "2.5.2",
  "com.fasterxml.jackson.core" % "jackson-databind" % "2.5.2",
  "com.fasterxml.jackson.core" % "jackson-annotations" % "2.5.2"
)

logback.xml

<property name="MONITORING_LOG" value="${LOG_DIR}/monitoring.log" />
<appender name="FILE_MONITORING" class="ch.qos.logback.core.rolling.RollingFileAppender">
    <file>${MONITORING_LOG}</file>
    <rollingPolicy class="ch.qos.logback.core.rolling.TimeBasedRollingPolicy">
        <fileNamePattern>${MONITORING_LOG}.%d.gz</fileNamePattern>
        <maxHistory>14</maxHistory>
    </rollingPolicy>
    <encoder class="ch.qos.logback.core.encoder.LayoutWrappingEncoder">
        <layout class="ch.qos.logback.contrib.json.classic.JsonLayout">
            <jsonFormatter class="ch.qos.logback.contrib.jackson.JacksonJsonFormatter">
                <!-- <prettyPrint>true</prettyPrint> -->
            </jsonFormatter>
            <timestampFormat>yyyy-MM-dd'T'HH:mm:ss.SSSXXX</timestampFormat>
            <includeContextName>false</includeContextName>
            <appendLineSeparator>true</appendLineSeparator>
        </layout>
        <charset>UTF-8</charset>
    </encoder>
</appender>

<root level="INFO">
    <appender-ref ref="FILE_MONITORING" />
</root>

monitoring.log

{"timestamp":"2015-04-05T14:45:28.481+09:00","level":"WARN","thread":"pool-1-thread-1-ScalaTest-running-SQSHelperSpec","logger":"helpers.aws.sqs.SQSHelperSpec","message":"com.amazonaws.AmazonClientException: Unable to load AWS credentials from any provider in the chain"}
{"timestamp":"2015-04-05T14:45:31.526+09:00","level":"WARN","thread":"pool-1-thread-1-ScalaTest-running-SQSHelperSpec","logger":"helpers.aws.sqs.SQSHelperSpec","message":"com.amazonaws.AmazonClientException: Unable to load AWS credentials from any provider in the chain"}
{"timestamp":"2015-04-05T14:45:31.775+09:00","level":"WARN","thread":"pool-1-thread-1-ScalaTest-running-SQSHelperSpec","logger":"helpers.aws.sqs.SQSHelperSpec","message":"com.amazonaws.AmazonClientException: Unable to load AWS credentials from any provider in the chain"}
{"timestamp":"2015-04-05T14:45:31.864+09:00","level":"WARN","thread":"pool-1-thread-1-ScalaTest-running-SQSHelperSpec","logger":"helpers.aws.sqs.SQSHelperSpec","message":"com.amazonaws.AmazonClientException: Unable to load AWS credentials from any provider in the chain"}

pom.xml

<dependencies>
    <dependency>
        <groupId>org.slf4j</groupId>
        <artifactId>slf4j-api</artifactId>
        <version>1.7.12</version>
    </dependency>
    <dependency>
        <groupId>ch.qos.logback</groupId>
        <artifactId>logback-core</artifactId>
        <version>1.1.3</version>
    </dependency>
    <dependency>
        <groupId>ch.qos.logback</groupId>
        <artifactId>logback-classic</artifactId>
        <version>1.1.3</version>
    </dependency>
    <dependency>
        <groupId>ch.qos.logback.contrib</groupId>
        <artifactId>logback-json-core</artifactId>
        <version>0.1.2</version>
    </dependency>
    <dependency>
        <groupId>ch.qos.logback.contrib</groupId>
        <artifactId>logback-json-classic</artifactId>
        <version>0.1.2</version>
    </dependency>
    <dependency>
        <groupId>ch.qos.logback.contrib</groupId>
        <artifactId>logback-jackson</artifactId>
        <version>0.1.2</version>
    </dependency>
    <dependency>
        <groupId>com.fasterxml.jackson.core</groupId>
        <artifactId>jackson-core</artifactId>
        <version>2.5.2</version>
    </dependency>
    <dependency>
        <groupId>com.fasterxml.jackson.core</groupId>
        <artifactId>jackson-databind</artifactId>
        <version>2.5.2</version>
    </dependency>
    <dependency>
        <groupId>com.fasterxml.jackson.core</groupId>
        <artifactId>jackson-annotations</artifactId>
        <version>2.5.2</version>
    </dependency>
</dependencies>