Build and publish image with Jenkins

Add a Jenkins pipeline to build and publish docker images
on the DockerHub.

The images are built on every branches but only pusblished on staging
and stable branches (i.e. develop and master by default).

Images are published with multiples tags:

- <image_name>:<short_commit_ref>
- <image_name>:<stable|staging>-latest

Jenkinsfile

+pipeline {
+
+    agent {
+        dockerfile {
+            filename 'Dockerfile'
+            dir 'ci'
+            args '--privileged -v /var/run/docker.sock:/var/run/docker.sock'
+        }
+    }
+
+    triggers {
+        gitlab(
+            triggerOnPush: true, 
+            triggerOnMergeRequest: true, 
+            branchFilterType: 'All',
+            cancelPendingBuildsOnUpdate: false
+        )
+    }
+
+    options {
+      gitLabConnection('Gitlab MIM')
+      gitlabBuilds(builds: [])
+    }
+
+    parameters {
+        string(defaultValue: "develop", description: 'Branche "staging"', name: 'stagingBranch')
+        string(defaultValue: "master", description: 'Branche "stable"', name: 'stableBranch')
+    }
+
+    environment {
+        IMAGE_NAME = "zephir-server-manager"
+        IMAGE_COMMIT_TAG =  env.GIT_COMMIT.substring(0,8)
+    }
+
+    stages {
+
+        stage('Build image') {
+            steps {
+               gitlabStage(STAGE_NAME) {
+                    withDockerHubCredentials {
+                        sh """
+                            # Construction de l'image
+                            docker build -t '${DOCKER_USERNAME}/${IMAGE_NAME}' .
+
+                            # Ajout du tag de commit
+                            docker tag '${DOCKER_USERNAME}/${IMAGE_NAME}:latest' '${DOCKER_USERNAME}/${IMAGE_NAME}:${IMAGE_COMMIT_TAG}'
+                        """
+                    }
+                }
+            }
+        }
+
+        stage('Publish staging image') {
+            when {
+                branch params.stagingBranch
+            }
+            steps {
+                gitlabStage(STAGE_NAME) {
+                    addTagAndPublishDockerImage(
+                        env.IMAGE_COMMIT_TAG, 
+                        "staging-latest"
+                    )
+                }
+            }
+        }
+
+        stage('Publish stable image') {
+            when {
+                branch params.stableBranch
+            }
+            steps {
+                gitlabStage(STAGE_NAME) {
+                    addTagAndPublishDockerImage(
+                        env.IMAGE_COMMIT_TAG, 
+                        "stable-latest"
+                    )
+                }
+            }
+        }
+
+    }
+
+}
+
+
+def gitlabStage(String stageName, Closure fn) {
+    gitlabBuilds(builds: [stageName]) {
+        gitlabCommitStatus(stageName) {
+            fn()
+        }
+    }
+}
+
+def withDockerHubCredentials(Closure fn) {
+    withCredentials([
+        usernamePassword(credentialsId: 'dockerhub', usernameVariable: 'DOCKER_USERNAME', passwordVariable: 'DOCKER_PASSWORD')]
+    ){
+        fn()
+    }
+}
+
+def addTagAndPublishDockerImage(String originalTag, String newTag) {
+    withDockerHubCredentials {
+        sh """
+            # Ajout du nouveau tag
+            docker tag '${DOCKER_USERNAME}/${IMAGE_NAME}:${originalTag}' '${DOCKER_USERNAME}/${IMAGE_NAME}:${newTag}'
+
+            # Publication de l'image sur le DockerHub
+            echo "${DOCKER_PASSWORD}" | docker login --username '${DOCKER_USERNAME}' --password-stdin
+            docker push '${DOCKER_USERNAME}/${IMAGE_NAME}:${newTag}'
+            docker push '${DOCKER_USERNAME}/${IMAGE_NAME}:${originalTag}'
+            docker logout
+        """
+    }
+}
\ No newline at end of file

ci/Dockerfile

+FROM docker:stable