How do I tag the current git changeset from inside the Jenkinsfile?

I want to tag the current git changeset and push the tag from inside the Jenkinsfile. If the tag already exists it must be replaced.

I want to use this logic in order to tag the build that passed with the snapshot tag, which would be a mobile tag.

How can I do this?

Here is the way I was able to implement this this way, but if you know a better way I am more than willing to hear it.

#!groovy

stage 'build'
node {

    repositoryCommiterEmail = 'ci@example.com'
    repositoryCommiterUsername = 'examle.com'

    checkout scm

    sh "echo done"

    if (env.BRANCH_NAME == 'master') {
        stage 'tagging'

        sh("git config user.email ${repositoryCommiterEmail}")
        sh("git config user.name '${repositoryCommiterUsername}'")

        sh "git remote set-url origin git@github.com:..."

        // deletes current snapshot tag
        sh "git tag -d snapshot || true"
        // tags current changeset
        sh "git tag -a snapshot -m \"passed CI\""
        // deletes tag on remote in order not to fail pushing the new one
        sh "git push origin :refs/tags/snapshot"
        // pushes the tags
        sh "git push --tags"
    }
}