Nov 25, 2020 Just follow the below steps to install Jenkins along with its suggested plugins. In case you are curious to know more about Jenkins, click here to find all the necessary details. The complete process to install Jenkins can be summarized in five steps: Install Java Version 8 – Jenkins is a Java based application, hence Java is a must. Aug 20, 2020 The resource utilization of the Jenkins slaves is very less if you do not have builds happening continuously. In this scenario, it is better to use ephemeral Docker containers as Jenkins build slaves for better resource utilization. As you know, spinning up a new container takes less than a minute; every build spins up a new container, builds the project, and is destroyed. This way, you can. Oct 06, 2020 Install Docker Compose on RHEL 8 / CentOS 8. Follow our separate guide on installation of latest Docker Compose on Linux. Install Docker Compose on Linux. For the sake of keeping this guide brief, we won’t dive into Docker compose usage. I’ll recommend you go through Official Docker documentation and Docker Compose documentation to learn more. Oct 11, 2020 For those using it, follow our guide below to install. How To Install Latest Docker Compose on Linux. More articles: Install Docker UI manager – Portainer. Ctop – Top command for container metrics. How to Setup Docker Private Registry on Ubuntu 18.04 / Ubuntu 16.04 with Letsencrypt. Install and Configure Docker Registry on CentOS 7.
- Docker Tutorial
- Docker Useful Resources
- Selected Reading
In Docker, everything is based on Images. An image is a combination of a file system and parameters. Let’s take an example of the following command in Docker.
The Docker command is specific and tells the Docker program on the Operating System that something needs to be done.
The run command is used to mention that we want to create an instance of an image, which is then called a container.
Finally, 'hello-world' represents the image from which the container is made.
Now let’s look at how we can use the CentOS image available in Docker Hub to run CentOS on our Ubuntu machine. We can do this by executing the following command on our Ubuntu machine −
Note the following points about the above sudo command −
We are using the sudo command to ensure that it runs with root access.
Here, centos is the name of the image we want to download from Docker Hub and install on our Ubuntu machine.
─it is used to mention that we want to run in interactive mode.
/bin/bash is used to run the bash shell once CentOS is up and running.
Displaying Docker Images
To see the list of Docker images on the system, you can issue the following command.
This command is used to display all the images currently installed on the system.
Syntax
Options
None
Return Value
The output will provide the list of images on the system.
Example
Output
When we run the above command, it will produce the following result −
From the above output, you can see that the server has three images: centos, newcentos, and jenkins. Each image has the following attributes −
TAG − This is used to logically tag images.
Image ID − This is used to uniquely identify the image.
Created − The number of days since the image was created.
Virtual Size − The size of the image.
Downloading Docker Images
Images can be downloaded from Docker Hub using the Docker run command. Let’s see in detail how we can do this.
Syntax
The following syntax is used to run a command in a Docker container.
Options
Image − This is the name of the image which is used to run the container.
Return Value
The output will run the command in the desired container.
Example
This command will download the centos image, if it is not already present, and run the OS as a container.
Output
When we run the above command, we will get the following result −
You will now see the CentOS Docker image downloaded. Now, if we run the Docker images command to see the list of images on the system, we should be able to see the centos image as well.
Removing Docker Images
The Docker images on the system can be removed via the docker rmi command. Let’s look at this command in more detail.
This command is used to remove Docker images.
Syntax
Options
ImageID − This is the ID of the image which needs to be removed.
Return Value
The output will provide the Image ID of the deleted Image.
Example
Here, 7a86f8ffcb25 is the Image ID of the newcentos image.
Output
When we run the above command, it will produce the following result −
Let’s see some more Docker commands on images.
docker images -q
This command is used to return only the Image ID’s of the images.
Syntax
Options
q − It tells the Docker command to return the Image ID’s only.
Return Value
The output will show only the Image ID’s of the images on the Docker host.
Example
Output
When we run the above command, it will produce the following result −
docker inspect
This command is used see the details of an image or container.
Syntax
Options
Repository − This is the name of the Image.
Return Value
The output will show detailed information on the Image.
Example
Output
When we run the above command, it will produce the following result −
Overview
This plugin allows containers to be dynamically provisioned as Jenkins nodes using Docker. It is a Jenkins Cloud plugin for Docker.
The aim of this docker plugin is to be able to use a Docker host to dynamically provision a docker container as a Jenkins agent node, let that run a single build, then tear-down that node, without the build process (or Jenkins job definition) requiring any awareness of docker.
The Jenkins administrator configures Jenkins with knowledge of one or more docker hosts (or swarms), knowledge of one or more 'templates' (which describe the labels/tags that this template provides, the docker image, how to start it, etc) and Jenkins can then run docker containers to provide Jenkins (agent) Nodes on which Jenkins can run builds.
See also
- Support and contribution guide
Note: There is more than one docker plugin for Jenkins. While this can be confusing for end-users, it's even more confusing when end users report bugs in the wrong place. e.g. if you are using Jenkins pipeline / workflow / Jenkinsfile builds with code including terms like docker.withDockerRegistry or docker.image etc then you're using the docker-workflow plugin and should go to its repository instead of this one.
Note: This plugin does not provide a Docker daemon; it allows Jenkins to use a docker daemon. i.e. Once you've installed docker on your OS, this plugin will allow Jenkins to use it.
A quick setup is :
- get a docker environment running
- follow the instructions for creating a docker image that can be used as a Jenkins Agent
Docker Environment
Follow the installation steps on the docker website.
If your Jenkins instance is not on the same OS as the docker install, you will need to open the docker TCP port so that Jenkins can communicate with the docker daemon. This can be achieved by editing the docker config file and setting (for example)
The docker configuration file location will depend your system, but it is likely to be /etc/init/docker.conf , /etc/default/docker or /etc/default/docker.io.
Multiple Docker Hosts
If you want to use more than just one physical node to run containers, you can use Docker Swarm Standalone or you can define more than one docker 'cloud'. The docker engine swarm mode API is not supported (at present; enhancement contributions would be welcomed).
To use the standalone swarm, follow docker swarm standalone instructions and configure Jenkins with the swarm's API endpoint.
Jenkins Configuration
Docker plugin is a 'Cloud' implementation. You'll need to edit Jenkins system configuration (Jenkins -> Manage -> System configuration) and add a new Cloud of type 'Docker'.
Configure Docker (or Swarm standalone) API URL with required credentials. The test button lets you check the connection.
Then configure Agent templates, assigning them labels that you can use so your jobs select the appropriate template, and set the docker container to be run with whatever container settings you require.
Creating a docker image
You need a docker image that can be used to run Jenkins agent runtime. Depending on the launch method you select, there's some prerequisites for the Docker image to be used:
Launch via SSH
- sshd server and a JDK installed. You can use jenkins/ssh-agent as a basis for a custom image.
- a SSH key (based on unique Jenkins master instance identity) can be injected in container on startup, you don't need any credential set as long as you use standard openssl sshd.
For backward compatibility or non-standard sshd packaged in your docker image, you also have option to provide manually configured ssh credentials - Note: If the docker container's host SSH key is not trusted by Jenkins (usually the case) then you'll need to set the SSH host key verification method to 'non-verifying'.
Launch via JNLP
- a JDK installed. You can use jenkins/inbound-agent as a basis for a custom image.
- Jenkins master URL has to be reachable from container.
- container will be configured automatically with agent's name and secret, so you don't need any special configuration of the container.
Launch attached
- a JDK installed. You can use jenkins/agent as a basis for a custom image.
To create a custom image and bundle your favorite tools, create a Dockerfile with the FROM to point to one of the jenkins/*-agent reference images, and install everything needed for your own usage, e.g.
Docker Install Jenkins Windows
Note on ENTRYPOINT
Docker Install Jenkins Iii
Avoid overriding the docker command, as the SSH Launcher relies on it.
You can use an Entrypoint to run some side service inside your build agent container before the agent runtime starts and establish a connection ... but you MUST ensure your entrypoint eventually runs the passed command:
Further information
More information can be obtained from the online help built into the Jenkins WebUI. Most configurable fields have explanatory text. This, combined with knowledge of docker itself, should answer most questions.
Docker Install Jenkins Instagram
Jenkins can be configured using Groovy code, and the docker plugin is no exception. For example, this configuration script could be run automatically upon Jenkins post-initialization or through the Jenkins script console. If run, this script will configure the docker-plugin to look for a docker daemon running within the same OS as the Jenkins master (connecting to Docker service through unix:///var/run/docker.sock) and with the containers connecting to Jenkins using the 'attach' method.