How do I use sh in Jenkins Global library - jenkins

Question

I am creating my own global library for Jenkins, which I have hosted on github, and to simplify some run-of-the-mill tasks, I wanted to add a function that returns the GIT tag.
Therefore I created something like this:
class Myclass{
static String getGitTag() {
return "${sh(returnStdout: true, script: 'git tag --sort version:refname | tail -1').trim()}"
}
}
... which results in this error:
No signature of method: static com.stevnsvig.jenkins.release.ReleaseUtil.sh()
So I'm left with two questions:
Is the solution to import the sh() library that Jenkins' groovy flavor obviously already has imported? (and if so how)
What is the best practice here? I am wondering why there isn't a GIT_TAG global variable when you use declarative pipelines, and something like this should (in my opinion) be easy as pie.
EDIT #1:
static String getGitTag() {
stdout = script.sh(script: "git tag --sort version:refname | tail -1", returnStdout: true)
return stdout.trim()
}
produces a similar error:
No signature of method: static com.stevnsvig.jenkins.release.ReleaseUtil.sh() is applicable for argument types: (java.util.LinkedHashMap) values: [[returnStdout:true, script:git tag --sort version:refname | tail -1]]
EDIT #2:
static String getGitTag() {
def stdout = "git tag --sort version:refname | tail -1".execute()
return stdout.in.text
}
completes, but the output is blank. Running the same command with pwd returns / which indicaes that the environment is not set, which makes sense, since all the commands running under Jenkins are designed to rununder pipelines
EDIT #3:
I went hunting for the import. Stumbled across the Jenkins CI project on github and started searching the many repositories. Found a promising one... and put a file called pwd.groovy in /vars with this content:
import org.jenkinsci.plugins.workflow.steps.durable_task.ShellStep
static String getPWD() {
def ret = ShellStep.sh(returnStdout: true, script: "git tag --sort version:refname | tail -1").trim()
echo "currently in ${ret}"
}
The error I got is a variation of the same. I guess since itsa plugin, the definition is different...
hudson.remoting.ProxyException: groovy.lang.MissingMethodException: No signature of method: static org.jenkinsci.plugins.workflow.steps.durable_task.ShellStep.sh() is applicable ...

Answer 1

Option 1) Use Groovy execute to run cmd and get its output as below
tag = "git tag --sort version:refname | tail -1".execute().text
Option 2) Use Jenkins pipeline step sh.
One concept need to get clear: the context of sh is global function is when sh used directly inside Jenkinsfile.
In your case, sh is used outside the Jenkinsfile. To make better understand I give an example Jenkinsfile.
pipeline {
stages('foo') {
steps {
sh 'pwd'
// In above sh step, there is an implicit `this` which represents the
// global object for Jenkinsfile, you can image sh 'pwd' to this.sh 'pwd'
//
// Thus if you want to use `sh` outside Jenkinsfile, you must pass down the
// implicit `this` into the file where you used `sh`
}
}
}
To address your issue
// ReleaseUtil.groovy
static String getGitTag(steps) {
// here `steps` is the global object for Jenkinsfile
// you can use other pipeline step here by `steps`
steps.echo 'test use pipeline echo outside Jenkinsfile'
steps.withCredentials([steps.string(credentialsId: 'git_hub_auth', variable: 'GIT_AUTH_TOKEN')]) {
steps.echo '....'
steps.sh '....'
}
return steps.sh(returnStdout: true, script:"git tag --sort version:refname | tail -1").trim()
}
// Jenkinsfile
import com.stevnsvig.jenkins.release.ReleaseUtil
pipeline {
stages('foo') {
steps {
ReleaseUtil.getGitTag(this)
}
}
}