The slack template that ships with zabbix has issues sending updates and resolved messages to multiple slack channels if the channel names are similar. eg. #zabbix and #zabbix-customer.

Both channels will get the initial problem event but only one channel will get the updated resolve message. So instead of checking for a partial match (.includes), I'm checking for exact channel names (===).

I also added support for service events with a default message to ping the channel. Probably not the most desirable for everyone but it works well for us.