Jenkins Docker 插件

原文地址：https://wiki.jenkins.io/display/JENKINS/Docker+Plugin

• Created by magnayn -, last modified by Nico Schmoigl on Mar 04, 2017

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Plugin Information

Plugin ID	docker-plugin	Changes	In Latest Release Since Latest Release
Latest Release Latest Release Date Required Core Dependencies	0.16.2 (archives) Sep 13, 2016 1.625.3 ssh-slaves (version:1.6) token-macro (version:1.7, optional) durable-task (version:1.3)	Source Code Issue Tracking Pull Requests Maintainer(s)	GitHub Open Issues Pull Requests Kanstantsin Shautsou (id: KostyaSha) Nigel Magnay (id: magnayn)
Usage		Installations	2016-Aug 4517 2016-Sep 4838 2016-Oct 4946 2016-Nov 5159 2016-Dec 5150 2017-Jan 5600 2017-Feb 5711 2017-Mar 6336 2017-Apr 6412 2017-May 6922 2017-Jun 7052 2017-Jul 7200

This plugin allows slaves to be dynamically provisioned using Docker.

Background

The aim of the docker plugin is to be able to use a docker host to
dynamically provision a slave, run a single build, then tear-down that
slave.

Optionally, the container can be committed, so that (for example)
manual QA could be performed by the container being imported into a
local docker provider, and run from there.

Setup

A quick setup is :

- get a docker environment running

- follow the instructions for creating a system that has an ssh server installed, and a JDK

- create a user (e.g: jenkins) that you can log in with

- store that image with a known ID (e.g: jenkins) so that it appears in the output of "docker images" command

Docker Environment

Follow the installation steps on docker.io.

If your host needs to allow connections from a jenkins instance
hosted on a different machine, you will need to open up the TCP port.
This can be achieved by editing the docker config file and setting (for
example)

DOCKER_OPTS="-H tcp://0.0.0.0:4243 -H unix:///var/run/docker.sock"

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)

Creating a docker image

Shortcut : Pulling a Docker image

You can pull a ready-made jenkins slave! (Use at your own risk.)

docker pull evarga/jenkins-slave

You need a docker image that has, as a minimum, an ssh server
installed. You probably want a JDK, and you will also want a 'jenkins'
user that can log in. Example session to do this:

root@Quordlepleen:/etc/init# docker pull ubuntu
Pulling repository ubuntu
...

root@Quordlepleen:/etc/init# docker run -i -t ubuntu /bin/bash

root@cff9f1f868b0:/# apt-get update

root@cff9f1f868b0:/# apt-get install openssh-server

root@cff9f1f868b0:/# mkdir /var/run/sshd

root@cff9f1f868b0:/# apt-get install openjdk-6-jdk

root@cff9f1f868b0:/# adduser jenkins
Adding user `jenkins' ...
Adding new group `jenkins' (1000) ...
Adding new user `jenkins' (1000) with group `jenkins' ...
Creating home directory `/home/jenkins' ...
Copying files from `/etc/skel' ...
Enter new UNIX password:
Retype new UNIX password:
passwd: password updated successfully
Changing the user information for jenkins
Enter the new value, or press ENTER for the default
Full Name []: Jenkins
Room Number []:
Work Phone []:
Home Phone []:
Other []:
Is the information correct? [Y/n] Y

root@cff9f1f868b0:/# /usr/sbin/sshd
root@cff9f1f868b0:/# exit

Once the container has been created, you need to commit it with a name to be used later, e.g: jenkins-1

root@Quordlepleen:/etc/init# docker ps -a
CONTAINER ID        IMAGE               COMMAND             CREATED             STATUS              PORTS               NAMES
cff9f1f868b0        ubuntu:12.04        /bin/bash           7 minutes ago       Exit 0                                  goofy_mccarthy    

root@Quordlepleen:/etc/init# docker commit cff9f1f868b0 jenkins-1
9ebe455d911904ce0939b41758af6b3159b91ccb0aa36e7bc911d96c8cc30e64

root@Quordlepleen:/etc/init# docker images
REPOSITORY          TAG                 IMAGE ID            CREATED             VIRTUAL SIZE
jenkins-1           latest              9ebe455d9119        3 minutes ago       422.1 MB
ubuntu              saucy               43461fe97ba1        5 days ago          144.6 MB
ubuntu              raring              5e94ff221e91        5 days ago          133.6 MB
ubuntu              quantal             3e47bae8d07a        5 days ago          127.6 MB
ubuntu              lucid               04180f9bd8a6        5 days ago          139.6 MB
ubuntu              precise             1e548c932d40        5 days ago          125.9 MB
ubuntu              12.04               8dbd9e392a96        9 months ago        128 MB
ubuntu              latest              8dbd9e392a96        9 months ago        128 MB
ubuntu              12.10               b750fe79269d        10 months ago       175.3 MB
cff9f1f868b0        ubuntu:12.04        /bin/bash           7 minutes ago       Exit 0                                  goofy_mccarthy     

You may wish to periodically update your build image -- e.g: if you are using maven, then it would be advantageous to update your local maven repository with released artifacts, to prevent having to download them again (and thus speeding up your builds).

Tips

It is very easy to update your jenkins image in docker -

root@krikkit:~# docker run -i -t jenkins-1 /bin/bash

# HACK ON IMAGE
root@d0ba389c07c5:/home/jenkins# exit
# Save new image
root@krikkit:~# docker commit d0ba389c07c5 jenkins-2

By default, the docker plugin will execute /usr/sbin/sshd -D, therefore it is not recommended that you set the ENTRYPOINT unless you plan to pass extra arguments from Jenkins

Configuration

Docker appears in the 'Cloud' section of the Jenkins configuration, select "Docker" from the "Add a new cloud" drop down menu.

The docker cloud configuration has the following options:

Name	Choose a name for this Docker cloud provider
Docker URL	The URL to use to access your Docker server API (e.g: http://172.16.42.43:4243)
Connection Timeout
Read Timeout
(Global) Container Cap	The maximum number of containers that may be allowed to be running on the Docker server at a time, 0 disables provisioning of instances altogether. For a detailed discussion on Container Caps and Instance Capacity, please read the section "Container Cap and Instance Capacity" below. Note: Technically, this is implemented differently: When trying to start a new container, the system checks the number of associated computers/slaves (also counting slaves which are not associated with this plugin) and checks it against this value of Container Cap. If the number of computers is higher than this cap, no new container is provisioned (see also JENKINS-36920)
Local Container Cap	The maximum number of container that this Jenkins instance may be allowed to be running on the Docker server at a time, 0 disables provisioning of instances altogether. For a detailed discussion on Container Caps and Instance Capacity, please read the section "Container Cap and Instance Capacity" below.

Images:

Click the Add button to add a new image.

The docker cloud configuration has the following options:

ID	The tagged name of the image that you wish docker to run (e.g "docker run -i -t <id> /bin/bash)
Labels	Labels to give these nodes (for limiting your builds)
Credentials	The SSH credentials to connect to the instance with
Remote Filing System Root	Root directory within your image for the Jenkins user to use
Remote FS Root Mapping	Enables the ability to browse workspaces of jobs being built using docker containers. Specify the location on the Jenkins master where the job workspaces will be and map them from the images using volumes, network shares, etc.
Instance Cap	Max number of instances of this image to run on the docker host (Note: instances not created by this plugin are also counted! see also JENKINS-36919), or 0 for unlimited For a detailed discussion on Container Caps and Instance Capacity, please read the section "Container Cap and Instance Capacity" below.
DNS	Set the DNS servers to use within your images
Port bindings	hostport:containerport
Bind all declared ports
Hostname
Idle termination time	The time in minutes after which an idle container will be dismantled (in the sense of a timeout)
JavaPath	The location within your image of the java executable for running the Jenkins slave
JVM Options
Docker Command	The command to run for this image, defaults to "/usr/sbin/sshd -D"
LXC Conf Options
Volumes	A space separated list of host volume mounts, e.g. /host/path:/container/path:ro
Volumes From
Run container privileged
Prefix Start Slave Command
Suffix Start Slave Command

Job Configuration

Commit on successful build	When a job completes, the docker slave instance is committed with tag based on the job name and build number
Additional tag to add
Push on successful build
Clean local images

Container Cap and Instance Capacity

Container cap and instance capacity both limits the number of
containers this plugin requests to be running on the Docker server at a
time. They serve a different purpose, but are very similar in general.
Thus, their difference may be hard to understand.

• The container cap is an "overall limit", which restricts the number
  of containers which may be running -- irrespectively which image is
  being used.
• The instance capacity is limiting the number of containers for a given image only.

Here's an example, which should make it clearer:

Let us assume that

• the container cap is set to 10,
• the instance capacity of image A is set to 6, and
• the instance capacity of image B is set to 5.

Let 5 containers of image A and 5 containers of image B be running on
the Docker server. Even though there is still one slot free of capacity
for image A, no new container will be provision: The container cap for
the Docker Host is already reached.

Let us assume that the container cap is changed to 12. Now, another
container can be provisioned for image A, as the instance capacity is
not reached yet. However, that does not hold true for image B, as the
instance capacity is set to 5 and already 5 containers are running.

How Container Cap and Instance Capacity is determined

Note
that both container cap and instance capacity is determined by listing
the containers running on the Docker server. It is a common
misunderstanding that this value equals to the number of slaves attached
to the Jenkins instance! However, keep in mind that there may be
containers running, which are not associated to the current Jenkins
instance (because they have been started from another's machine, or they
got decoupled but not cleaned up properly yet, ...)

Triton and Container Cap / Instance Capacity

If your Docker server is running Triton, be aware of the fact that -
in contrast to the Docker reference implementation - containers are
private to the user you are using to log on.
This implies the effect that the container cap and the instance capacity
is calculate relative to the user only and is not applied globally
(which can be a good or a bad thing, depending on your use case).

Known Issues

If you have trouble selecting "Docker" from the clouds list, then you need to update your credentials plugin.

Changelog

See https://github.com/jenkinsci/docker-plugin/blob/master/CHANGELOG.md