Figure 3 – Docker Container mounts a directory on the host and maps to port 3080 on the host. A corresponding docker command could be: docker run -p 3080:80 -v ~/container_mount_point:/var/www jenkins/jenkins:ltsDocker containers based on an docker image. By running a container, you start an instance of the image. A container behaves like another server/machine. Things to configure a container with: mount a volume to persist/access data, configure the network (e.g. map ports), run commands inside the container, e.g. via an interactive shell.

Install docker

I don’t want to go into detail. There is detailed description on https://docs.docker.com/install/ for all common operating systems.

If you are new to docker, here is a useful cheat sheet: https://www.docker.com/sites/default/files/Docker_CheatSheet_08.09.2016_0.pdf

Start a Jenkins docker container

First you need to pull an image. You can use the plain Docker Jenkins image from https://hub.docker.com/r/jenkins/jenkins/, our adjusted image https://hub.docker.com/r/connydockerid/jenkins-image-nodejs-android/ or build one yourself. If you build on yourself you have to build it on the server with the “docker build …” command, or build it anywhere and upload it to a docker registry like https://hub.docker.com.

docker pull connydockerid/jenkins-image-nodejs-android:latest

Now run the container with the following command:

docker run -p 80:8080 -v /data/jenkins_mount_point:/var/jenkins_home connydockerid/jenkins-image-nodejs-android:latest

Note: Jenkins runs by default on port 8080.

Explained:

docker run […] connydockerid/jenkins-image-nodejs-android:latest starts a container of the provided image

-p 80:8080
Maps the port 8080 of the container to the port 80 of the host (our server). Jenkins will be running on port 8080 inside the container and will be reachable on port 80 on our server with this configuration, e.g. myserver.com:80 (yes, 80 is default, but for the sake of clarity…).

-v /data/jenkins_mount_point:/var/jenkins_home
Mounts the /var/jenkins_home directory to /data/jenkins_mount_point on the host. Jenkins will store all data in this directory. Persisting it will persist the state of Jenkins.

If everything worked out, you should now be able to reach your server.

Useful commands

#Lists all containers, running and not running

nbsp; docker ps -a
# Starts an interactive shell in the container
nbsp; docker exec -it CONTAINER_ID /bin/bash
# Starts|stops a container
nbsp; docker start|stop CONTAINER
Frequent Problems with our virtual server
Request timeout trying to access something in the internet from the server
This could be a firewall issue: Most companies and universities have strict firewall rules which do not allow to communicate on nonstandard ports / protocols. If you have for example an external hosted MongoDB like mlab you will communicate with this database on a nonstandard port like 5342. A timeout can be a hint to a firewall issue.
No internet / no DNS
Maybe an issue with your DNS – any requests using a domain name will fail. Execute the following command to investigate
nbsp; nslookup google.com
 If the response is “server can’t find google.com: SERVFAIL” contact you administrator and tell him you DNS does not work.
Cannot reach my server from outside
You might have started several containers. Only one of them can occupy the port 80 – you might have used other (nonstandard) ports for the other containers. And there it is again: nonstandard. This could be again a firewall issue. Contact you administrator and ask him to open those ports.
Conclusion
There is no perfect solution to all problems. You have to consider many aspects like project size, project requirements, technologies and your operational environment before setting up a continuous integration and delivery environment. The solution must fit the problem and you should reflect every now and then how (or if) you benefit from the system you set up.