How to change Email-ext plugin to load script from custom location - jenkins

Question

I like to commit my Jenkins email script to my working copy and use it with Email-ext.
So I wrote something like :
pipeline {
agent any
stages {
stage('Build') {
steps {
echo 'Building...'
}
}
}
post {
always {
echo 'Sending email...'
emailext body: '''${SCRIPT, template="${WORKSPACE}\\Src\\Scripts\\Jenkins\\groovy-html2.template"}''',
mimeType: 'text/html',
subject: "[Leeroy Jenkins] ${currentBuild.fullDisplayName}",
to: "user#company.com",
replyTo: "user#company.com",
recipientProviders: [[$class: 'CulpritsRecipientProvider']]
}
}
}
But I get the following mail:
Groovy Template file [${WORKSPACE}SrcScriptsJenkinsgroovy-html2.template] was not found in $JENKINS_HOME/email-templates.

Answer 1

Templates must live in the correct directory for security reasons. If you want to keep them in a SCM I suggest you create a Jenkins job that checks out that SCM to the correct directory. Technically though that directory shouldn't be writable but probably is. Alternatively you can use the groovy code in the pipeline itself

Answer 2

On Jenkins 2.190, using a local workspace file as a jelly template, works well. It is pulled with SCM step during the build, and the correct html content is received.
This is the Default Content of my email-ext configuration:
${JELLY_SCRIPT,template="${WORKSPACE}/some_dir/email_template.jelly"}

Answer 3

Solve it by manually overriding the file using command line:
pipeline {
agent any
stages {
stage('Build') {
steps {
echo 'Building...'
}
}
}
post {
always {
echo 'Sending email...'
bat "copy /Y ${WORKSPACE}\\Src\\Scripts\\Jenkins\\groovy-html2.template \"${JENKINS_HOME}\\email-templates\\groovy-html2.template\""
emailext body: '''${SCRIPT, template="${WORKSPACE}\\Src\\Scripts\\Jenkins\\groovy-html2.template"}''',
mimeType: 'text/html',
subject: "[Leeroy Jenkins] ${currentBuild.fullDisplayName}",
to: "user#company.com",
replyTo: "user#company.com",
recipientProviders: [[$class: 'CulpritsRecipientProvider']]
}
}
}
A bit crude, but it works.