Split Jenkinsfile

common.groovy

def notify(message) {
    def channel = "#notify-channel"
    def domain = "daipresents"
    def token = "TOKEN_IS_HERE"
    def slack_msg = "${message}"
    slackSend channel: "${channel}", color: "good", message: "${slack_msg}", teamDomain: "${domain}", token: "${token}"
}
return this

ErrorLog

Running on master in /var/lib/jenkins/workspace/MY_JOB_NAME
[Pipeline] {
[Pipeline] pwd
[Pipeline] load
[Pipeline] // load
[Pipeline] }
[Pipeline] // node
[Pipeline] End of Pipeline
java.nio.file.NoSuchFileException: /var/lib/jenkins/workspace/MY_JOB_NAME/common.groovy

Jenkinsfile

node {
    checkout scm
    common = load "${pwd()}/common.groovy"
    
    common.notify("This is message")
}