I’m trying to get fluentd to send messages to slack. I installed fluentd via curl and fluentd-plugin-slack via fluent-gem install fluent-plugin-slack however, I’m getting these errors when trying to systemctl start fluentd:

2024-06-03 21:05:47 +0000 [warn]: 'time_format' specified without 'time_key', will be ignored
/opt/fluent/lib/ruby/gems/3.2.0/gems/fluent-plugin-slack-0.6.7/lib/fluent/plugin/out_slack.rb:137:in `configure': undefined method `unescape' for URI:Module (NoMethodError)

        @channel = URI.unescape(@channel) # old version compatibility
                      ^^^^^^^^^

My /etc/fluent/fluentd.conf looks like this:

<source>
  @type tail
  path /var/log/secure
  pos_file /var/log/td-agent/selinux_secure.pos
  tag selinux.secure
  <parse>
    @type syslog
  </parse>
</source>

<match selinux.secure>
  @type copy
  <store>
    @type stdout
  </store>
  <store>
    @type slack
    webhook_url $SLACK_WEBHOOK_URL
    channel $SLACK_CHANNEL
    message_keys message
    flush_interval 5s
    buffer_chunk_limit 1m
    buffer_queue_limit 1
  </store>
</match>

Any ideas? (edited)