Issue

I would like to build my own docker images in CloudBees Core on Modern Cloud Platforms

Environment

Resolution

There are two approaches

1) Use Kaniko to build Dockerfiles without Docker
2) Use DinD by creating a new Pod Template and including the Container Template required

CloudBees recommends to follow the Kaniko approach

1) Kaniko approach

Please refer to Using Kaniko with CloudBees Core

2) DinD approach

Risks

There are some risks from using “Docker in Docker” (DinD) and the “Docker socket” for building containers on CloudBees Core for Modern Cloud Platforms.

resources launched outside of the k8s scheduler’s oversight are not properly accounted for and may lead to resource over-utilisation
resources launched by DinD will not be cleaned up by the k8s scheduler and may consume CPU and memory resources until the instances are removed
exposing the docker.sock to processes effectively grants host root access to the container processes

Instructions

Following we provide two options to define your DIND Agent Pod Templates:

Kubernetes Pod Templates GUI
Jenkinsfile

Kubernetes Pod Templates GUI

Kubernetes Pod Templates can be added at CJOC or Master level.

In CJOC, access to CJOC main page, click on the view All and open the kubernetes shared cloud config page.
In a Master, go to Manage Jenkins > Kubernetes Pod Template.

Add a new Pod Template

Click on the Add Pod Template button and fill the following fields

Name   : pod-dind
Labels : pod-dind
Usage  : Only build jobs with label expressions matching the node

Add the `DinD` container

Click on the Add Container button and use one of the docker DinD images:

Name                   : dind
Docker image           : docker:18.06.1-ce-dind
Working directory      : /home/jenkins/agent
Command to run         : (empty field)
Arguments to pass to the command: (empty field)
Allocate pseudo-TTY    : checked
Run in privileged mode : checked

Testing job

In order to test the Pod Template, create a new Pipeline job using the following code.

node('pod-dind') {
    container('dind') {
        stage('Build My Docker Image') {
            sh 'docker info'
            sh 'touch Dockerfile'
            sh 'echo "FROM centos:7" > Dockerfile'
            sh "cat Dockerfile"
            sh "docker -v"
            sh "docker info"
            sh "docker build -t my-centos:1 ."
        }
    }
}

Jenkinsfile

pipeline {
  agent {
    kubernetes {
      yaml """
apiVersion: v1
kind: Pod
metadata:
  labels:
    some-label: dind-agent
spec:
  containers:
  - name: dind
    image: docker:18.06.1-ce-dind
    imagePullPolicy: Always
    tty: true
    securityContext:
      privileged: true
"""
    }
  }
  stages {
    stage('Build My Docker Image')  {
      steps {
        container('dind') {
            sh 'docker info'
            sh 'touch Dockerfile'
            sh 'echo "FROM centos:7" > Dockerfile'
            sh "cat Dockerfile"
            sh "docker -v"
            sh "docker info"
            sh "docker build -t my-centos:1 ."
        }
      }
    }
  }
}

Expected output

It would be similar to the following

[Pipeline] node
Agent pod-dind-xwhnz is provisioned from template Kubernetes Pod Template
Agent specification [Kubernetes Pod Template] (pod-dind): 
* [dind] docker:18.06.1-ce-dind(resourceRequestCpu: , resourceRequestMemory: , resourceLimitCpu: , resourceLimitMemory: )

Running on pod-dind-xwhnz in /home/jenkins/workspace/dind-test
...
[Pipeline] sh
[dind-test] Running shell script
+ docker info
Containers: 0
 Running: 0
 Paused: 0
 Stopped: 0
Images: 0
Server Version: 18.06.1-ce
...
[Pipeline] sh
[dind-test] Running shell script
+ docker build -t my-centos:1 .
Sending build context to Docker daemon  2.048kB

Step 1/1 : FROM centos:7
7: Pulling from library/centos
aeb7866da422: Pulling fs layer
aeb7866da422: Verifying Checksum
aeb7866da422: Download complete
aeb7866da422: Pull complete
Digest: sha256:67dad89757a55bfdfabec8abd0e22f8c7c12a1856514726470228063ed86593b
Status: Downloaded newer image for centos:7
 ---> 75835a67d134
Successfully built 75835a67d134
Successfully tagged my-centos:1
[Pipeline] }
[Pipeline] // stage
[Pipeline] }
[Pipeline] // container
[Pipeline] }
[Pipeline] // node
[Pipeline] }
[Pipeline] // podTemplate
[Pipeline] End of Pipeline
Finished: SUCCESS

Depending on the version you are running, you may receive an error during your test build similar to process apparently never started in /home/jenkins/workspace/dind-test. This is due to a change in the default working directory for containers. If you receive this error, change the Working directory to: Working directory: /home/jenkins/agent. This should be auto-populated when creating your container if you need to use this new location.

Tested product/plugin versions

The latest update of this article has been tested with

CloudBees CI on Modern Managed Master 2.249.2.4

How to build my own docker images in CloudBees CI (CloudBees Core) on Modern Cloud Platforms