Jenkins not building docker image, can't find the docker command

Question

I'm trying to make Jenkins build and publish a docker image of my project after every successful build of my Maven Java project.

I have a Dockerfile and a Jenkinsfile at the root of the project.

Here's my Jenkinsfile?

pipeline {

    agent {
        docker {
            image 'maven:3-alpine'
            args '-v /root/.m2:/root/.m2'
        }
    }

    options {
        skipStagesAfterUnstable()
    }

    stages {
        stage('Build') {
            steps {
                sh 'mvn -B -DskipTests clean package'
            }
        }

        stage('Build image') {
            steps {
                script {
                    docker.withRegistry('http://localhost:5000') {
                        def customImage = docker.build("my-image:${env.BUILD_ID}")
                        customImage.push()
                    }
                }
            }
        }
    }

    post {
        always {
            archiveArtifacts artifacts: 'target/**/*.jar', fingerprint: true
        }
    }
}

When Jenkins tr to build this project, it returns the given error message:

+ docker build -t my-image:13 .

/var/jenkins_home/workspace/powertiss-eureka_master@tmp/durable-b9e45059/script.sh: line 1: docker: not found

What am I doing wrong here?

*edit: My Dockerfile

FROM openjdk:8-jdk-alpine
VOLUME /tmp
COPY target/projectName-SNAPSHOT.jar app.jar
ENTRYPOINT ["java","-Djava.security.egd=file:/dev/./urandom","-jar","/app.jar"]

Answer 1

The maven:3-alpine image most likely does not include Docker. You need to choose an image that has Docker included.