hostname always comes in empty in slack messages

[andreygubarevich]

Hello!

I was able to successfully set up this module and use it however I faced an issue with 'hostname' always coming as empty.
Same if I use property("HOSTNAME") instead. However the if condition which uses it works just fine.
Can you take a look.

My logback config looks like this:

<if condition='!property("HOSTNAME").contains("local")'>
        <then>
            <appender name="SLACK" class="jp.co.dwango.logback.SlackWebhookAppender">
                <webhookUrl>xyz</webhookUrl>
                <timeout>50000</timeout>
                <payload>
                    {
                    "channel": "#channel-layer-notifications",
                    "username": "username",
                    "icon_emoji": emoji,
                    "link_names": 1,
                    "attachments": [{
                    "title": level,
                    "color": color,
                    "fields": [
                    {
                    "title": "Hostname",
                    "value": hostname,
                    "short": true
                    },
                    {
                   "title": "Message: ",
                    "value": message,
                    "short": false
                    }
                    ]}
                    ]}
                </payload>
            </appender>
            <appender name="ASYNC_SLACK" class="ch.qos.logback.classic.AsyncAppender">
                <appender-ref ref="SLACK" />
                <filter class="ch.qos.logback.classic.filter.ThresholdFilter">
                    <level>ERROR</level>
                </filter>
            </appender>
            <root level="ERROR">
                <appender-ref ref="ASYNC_SLACK" />
            </root>
      </then>
      <else>
          ... other config
      </else>
</if>