Here is a quick and full example to build a docker image from private GitHub repo and push to docker hub with declarative pipeline in Jenkins.

I created a sample repo with basic Dockerfile and Jenkinsfile

$ cat Dockerfile

FROM ubuntu:20.04
RUN apt update && apt upgrade -y

Configure Jenkins

Ensure that you installed docker engine on Jenkins instance and git, docker plugins

Install Docker-CE on Ubuntu 18 from https://docs.docker.com/engine/install/ubuntu/

After that, allow Jenkins users to access the docker socket.

sudo usermod -aG docker jenkins
sudo systemctl restart jenkins

Test your docker access with Jenkins user

$ sudo su - jenkins
$ docker ps

CONTAINER ID        IMAGE               COMMAND             CREATED             STATUS              PORTS               NAMES

Create credentials on Jenkins for GitHub and docker hub

To create a GitHub credentials we need to create a token. Check the following URL to create a personal API Token

https://support.cloudbees.com/hc/en-us/articles/234710368-GitHub-Permissions-and-API-token-Scopes-for-Jenkin

To create a GitHub credentials go to Manage Jenkins->Manage Credentials(Under Security) click to Jenkins Store

#pipeline #docker #github #jenkins