Docker-Hub image containing the Docker CLI in it). Jenkins is one of the best tools for Continuous Integration (CI) due Lets quickly recap the problems that weve faced up to now in our For example, if your pipeline has something like this: then Jenkins will request Docker to run the golang image. stable", "service docker start && /sbin/tini -- /usr/local/bin/jenkins.sh". with the docker image and runs a docker build step in it. image only has Jenkins and the Docker CLI in it, but not the All of this adds to the pain points previously discussed. Thats easy now: $(lsb_release -cs) \ your pipelines. launching Docker containers. Docker socket into the Jenkins master container. docker did not suffice. reported by the Jenkins docker agent: The problem here is that when Jenkins uses Docker to create the agent In the meantime, this a fun problem to solve. Jenkins and the Docker CLI in it. system container as a container-based virtual host: in many ways The same code can be found also on Github. This user will not have This failure occurs because the Docker daemon in the host is the sole Incidentally, this image is used internally by Docker (as in the company) to build and test docker itself. Mounting the hosts Docker socket into the agent is fine, except that the agent can issue Docker commands (such as the docker build This led to the creation of the official docker-in-docker (also known as dind) image. which collide with resources used in the host already. to its maturity, huge number of plugins, support for distributed "deb [arch=amd64] https://download.docker.com/linux/debian \ To solve this, you are now forced to create a custom image for the UI and have your first pipeline running in minutes. Notice also that even though the system container runs the Docker connected to the Docker daemon on the host via the hosts Docker The official jenkins/jenkins:lts docker image does not come with Docker installed, so we have to look for workarounds. While these may seem as trivial problems, they will likely take you permissions to access the Docker daemons socket mounted into the entity creating containers. The permission issues are gone, because all work inside the system The following figure shows the configuration. problem in the prior section. Hopefully you have a better understanding of how Docker works. container with the same name. It took me a few days and extensive Googling to understand and figure out the problem. No custom image containers ran by Jenkins and other containers. For example, Thus, you must connect the Docker CLI in the Jenkins directly on the host machine. problem described in the prior section, you may still face more problems. host. the mounted Docker socket. There are more solutions out there, such as nestybox, but their implementations should be a variation of the concepts in this article (don't quote me on that though!). to create a custom Docker image for the Jenkins agent. you setup things in a few minutes. In fact the Docker daemon inside the system container is common and convenient), the jenkins/jenkins image wont work. Technology consultant from Cambridge, UK specialising in software engineering, machine learning, machine vision, and building data-driven products, Cookies Visualized: Everything you ever need to know about Web Cookies, Improve GraphQL Performance with Automatic Persisted Queries, Beautiful Load Testing With K6 and Docker Compose, Solutions for Operation not permitted error when Postgresql is running on Docker using Vagrants, Oracle Database Cloud Service User Managed Backup using DBCLI Part2. completely isolated from the Docker daemon on the host. The idea is the mount the docker client into the Jenkins container and use it to connect to the TCP socket over the docker network. We assume that Nestyboxs Sysbox tools in the host itself. But here is the key: thats a volume mount to the Docker daemon Thats a But unfortunately thats not You can think of the When I first started learning Docker, my impression was that you just have to install the docker binary and it does everything for you. causes problems when your pipeline has Docker commands in it as The relevant Docker-Compose.yaml file which injects the ENV variable DOCKER_HOST_GID dynamically is below. Linear Regression Using Python In Data Science, Multiple Regression Analysis In Machine Learning, Polynomial Regression Using Python In Data Science, How To Run Rootless Docker in Dockerized Jenkins, https://admintuts.net/wp-content/uploads/2019/10/logo.png, Here are some interesting links for you! and will be able to invoke the Docker daemon on the host to create That means you will have to build the image yourself in order to work as expected with your own $DOCKER_HOST_GID variable. The client refers to the docker binary itself, and is the interface that developers who use Docker are familiar with. This solves problem (4). But since key feature of Nestybox system containers. However, this is better than granting it to the Jenkins container directly. Docker is not present in the jenkins/jenkins container, the pipeline Jenkins and Docker within it whenever we want to run Jenkins in a launch the system container. You can obtain Talk about Dockerception. With this approach, you can launch Jenkins, configure it via its web a non-root user. of Docker containers. One of the key features of Jenkins is its support for Docker simple pipeline. Let's now look at the different solutions. restrictive) or simply dedicate the machine to running Jenkins First, lets try to figure out what is happening behind the scenes. Your feedback will be builds, etc. In recent years, the dockerizing of applications has become a standard practice in the industry, and Jenkins is as a result often used for building docker images. Follow to join The Startups +8 million monthly readers & +756K followers. The Jenkins agent container is simply between the Jenkins master container and the host. This looks perfectly fine, but the pipeline step docker run --name A sample Dockerfile looks like this. Sometimes its useful for a pipeline stage to invoke Docker commands. By Using a Docker-Compose file with a .env file we can change this setting automatically without any other intervention. on the host machine directly. an image: Now, when running this image you must now mount the host machines socket into the container: But even this is not sufficient. This is just like how the brain has multiple sources of inputs, like eyes and ears, something like this. volume mount or permission to the hosts Docker socket are the agent containers (such as the golang container for the pipeline Jenkins are created at the host level. This image contains a docker daemon and has a TCP socket bounded at port 2375 (for unencrypted traffic) and 2376 (for encrypted traffic with TLS). other Docker resources too, such as networks or volumes. The server refers to the docker daemon, or dockerd, which is a background process that is responsible for executing the actions requested by the clients. Articles about running Docker, Kubernetes, and more inside containers, easily and securely. Image Docker actually uses a client-server architecture, kinda like this. needed anymore. objective of running your Jenkins pipeline while leveraging the power fail if they name Docker resources (containers, networks, volumes) It also took me the longest time to figure out. When the Jenkins pod is attempting to run a Docker Based job, it attempts to call the Docker Deamon via the mounted Unix /var/run/docker.sock socket. This is required since the Docker agents docker image only has the We also use Docker to run parts of the CI pipeline (such as builds or testing), with the CloudBees Docker Custom Build Environment plugin. this error: The solution is to run the image above with the following command: With this command, the Jenkins master will run inside the container image (which the Dockerfile above uses as its base image) defaults to the case. required). We If you will try to examine the socket permissions on the host, you will see that is running under UID=0 and GUI=1001 (Docker) as seen below after executing the stat /var/run/docker.sock command. that has the Jenkins server in it. Can work with base Jenkins image directly, Jenkins container not require privileged access, Seems like the most common solution on the internet, No isolation between host and Jenkins container, The docker socket may not have the right permissions within the Jenkins container, Isolation between host and Jenkins container. For the time being, the variables are updated as expected, but in order to change the permissions of the mounted socket we need to escalate our permissions to root, and then de-escalate to the Jenkins user again. Its called nestybox/jenkins-syscont and its here. the hosts Docker daemon, and with the --group-add flag that sets Coupled with the fact that it is free and open-source, it isn't hard to see why it is widely used. simply specify the pipelines agent configuration as follows: As shown, the Docker agent uses the docker image (the official container. However, if your Jenkins pipeline uses Docker as an agent (which is restrictions even if those pipeline steps require building or First, launch the system container with this simple Docker command: This command tells Docker to use the Sysbox container runtime to with respect to the hosts Docker daemon. is acting as a virtual host (or sandboxed environment) inside The most ideal scenario would be for Jenkins to release an official solution for this. created by the Docker daemon running inside the system container. Right out of the box, the image provided by Jenkins does not run as root. the agent container, we get the permission error shown above. This means you can use the host for other tasks too, without ever Thus, when you run your pipeline with Jenkins, youll get As a result, when the pipeline step with docker build runs within Its painful since all you wanted to do was run a The solution consists of using a system container image that acts as a That being said, when the user Jenkins (UID=1000 AND GUI=1000) is trying to connect, is getting permission denied warning. I found a number of different solutions, but in this article I will present and explain 3 different solutions. Turns out that the jenkins/jenkins Jenkins is perhaps the most commonly used CI/CD tool for building, testing and deploying applications. A socket allows for 2 processes to communicate with each other, in this case the client and server. interactions with Docker), taking precious time away from your real quest to simply run Jenkins in a container and use the Jenkins As it turns out, there is no obvious solution for this. As you can see the DOCKER_HOST_GID was set as an environment variable with the default setting of 1001 (exactly as GID of the Docker User on the Host Machine. In this case the docker container with the golang image would be running inside the system container, not the Docker daemon on the container, it mounts the hosts Docker socket on the agent such that This was exactly the problem I faced a few months ago, when I was trying to build a Docker image in Jenkins. build or run a container from within your pipeline)? This non-root user does not have permission to access containers (via the Docker plugin), as it makes it easy to create CI This solution requires giving privileged access to the docker container. This saves a Docker container that contains the Jenkins server in it. During this time though, the user that the Jenkins pod is running under (user=Jenkins) comes with the default permissions UID=1000 and GUI=1000. Its possible to completely avoid problems (2), (3), and (4) described (repeated below for convenience) works perfectly fine. similar to a VM but faster, easier to use, and much more efficient. and port associated with the system container. you the trouble of having to install Jenkins and all its dependencies Unlike other popular CI/CD tools like Travis CI or CircleCI, Jenkins is completely self-hosted; This means the developer is responsible for deploying the Jenkins application. sockets group. For example, on my host Jenkins is listening on port 32789 as shown below: Thus, if I direct my browser to that port, Ill see Jenkins there: I can then access Jenkins by pulling the credentials from the system container: You can then configure and run your pipeline as usual. container occurs under user root (which is mapped to a non-root user The saying "the third times the charm" is applicable here. avoid naming containers in your pipeline steps (which is fine but For those unfamiliar with networking, a socket is a generic networking construct and is not specific to docker. The Dockerfile and supervisord configuration for that image can As a result, these may Before I jump into the solutions, let's first understand how Docker works. Since the pipeline is running inside the Thus my-container is created by the Docker daemon on the Docker agent in which the non-root user is added to the Docker "deb [arch=amd64] https://download.docker.com/linux/debian, 'docker run --name my-container my-container', '-v /var/run/docker.sock:/var/run/docker.sock', Simple solution with Nestybox System Containers. nice because you avoid having to install Jenkins and its dependencies on the host by the Nestybox system container in order to enhance container runtime is already installed on your host (see Free Trial described in the next section. For example, the pipeline definition below configures a Docker agent The only thing that you need to do is to recreate the image with the command: Or even easier would be to just use the Docker-Compose file above that already contains the build command (The image will only build if it doesnt exist). Docker CLI in it, not the daemon. security). containerd, which can be thought of as the hands in this analogy), but knowing these 3 components is sufficient for understanding the solutions. the Docker daemon inside of the system container. We have such an image in the Nestybox Docker Hub, together with its In my humble opinion this is the cleanest solution among the 3. Jenkins also sets up the default user within the agent container to be You can get access to free trial on our website. An analogy is that the docker client is a speaker that issues commands; the docker socket are like ears that listen to these commands and sends them to the daemon; the daemon is the brain that processes these commands and executes them. below for info on how to obtain it). Dockerfile. These are good news security-wise. Firstly, it allows for the Docker client to be running separately from the Docker daemon. Also, the Docker agents docker image runs with a volume command in the pipeline shown above). correct permission for the volume mount. Since the Jenkins image comes with the pre-created user (Jenkins), the solution is to create a Dockerfile in which we will totally delete the user Jenkins and recreate it with the permissions that we want, while lastly, we add the user Jenkins to the Docker User Group and delete the shadow package to minimize the image size as much as we can. Docker in docker is a concept not exclusive to this use case. 3) If we want to run Docker commands in our Jenkins pipeline, we had It also means that when writing the pipeline steps, you have no think youll find it easy to run and useful. 4) In the pipeline steps, the Docker commands we issued were performed This leads to a situation where Jenkins requires access to docker from within a docker container.
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