Since Jenkins is running in a docker container, in Splunk for Jenkins Configuration, you have to give - HTTP Input Host as 'host.docker.internal' and NOT as 'localhost' If you specify localhost, then jenkins docker container will try connecting to 8088 on the same container, for which it will get 'Connection Refused'. Whereas host.docker.internal refers to the Host machine on which both Jenkins container and Splunk are running, Hence Jenkins will be able to connect to Splunk on 8088 ... View more