Introducing Docker

1. Introducing Docker Francesco Pantano francesco.pantano@opmbx.it March 17, 2016

2. #Outline 1 Virtualization 2 Containers 3 Docker in practice 4 Docker Compose 5 Continuous integration Virtualization 2/24

3. Thinking about VMM The Key component is the Hypervisor, a Virtual Machine Monitor that can be thought as an API that provides access to the hw level for the VMs. Hosted () abstract guest operating systems from the host one Bare Metal() run directly on the host’s hardware VMware Workstation/Player, VirtualBox and QEMU are examples of hosted hypervisors Virtualization 3/24

4. Deep into Light Virtualization Born on top of LXC project, a set of tools built on a userspace interface for the Linux kernel containment features, LV uses the following kernel features to contain processes: Kernel namespaces (ipc, uts, mount, pid, network and user) Chroots (using pivot root) CGroups (control groups) Relies on your existing system; Services stay in the kernel host; Virtualization 4/24

5. Cgroups Cgroups (abbreviated from control groups) is a Linux kernel feature that limits, accounts for and isolates the resource usage (CPU, memory, disk I/O, network, etc.) of a collection of processes. Cgroups provides: Resource Limiting: groups can be set to not exceed a conﬁgured memory limit Prioritization: some groups may get a larger share of CPU utilization or disk I/O Accounting: measures how much resources certain systems use Control: freezing the groups of processes, their checkpointing and restarting Virtualization 5/24

6. Namespaces Isolation Groups of processes are separated so they cannot ”see” resources in other groups. For example, a PID namespace provides a separate enumeration of process identiﬁers within each namespace. struct upid { int nr; // the PID value // namespace where this PID is relevant struct pid_namespace *ns; // ... }; struct pid { // number of upids int level; // array of upids struct upid numbers [0]; }; Virtualization 6/24

7. The Layered Filesystem Union ﬁle systems, or UnionFS, are ﬁle systems that operate by creating layers, making them very lightweight and fast. Copy-On-Write It enables sharing that promotes smaller images Virtualization 7/24

8. #Outline 1 Virtualization 2 Containers 3 Docker in practice 4 Docker Compose 5 Continuous integration Containers 8/24

9. Why Containers? Fast deployment time It’s cheap and ﬂexible Scalability and support Docker as standardized platform Docker is a platform for developing, shipping, and running applications using container virtualization technology. Containers 9/24

10. The Docker environment Containers 10/24

11. Docker: Terminology Image: layered filesystem where each layer references the layer below Dockerfile: build script that defines: an existing image as starting point a set of instructions that augment that image (each of which results in another layered filesystem) metadata such as ports exposed the command to executed when the image is run Container: runtime instance of an image plus a read/write layer Docker Hub: centralized repository of docker images Containers 11/24

12. #Outline 1 Virtualization 2 Containers 3 Docker in practice 4 Docker Compose 5 Continuous integration Docker in practice 12/24

13. Quick Start Linux - run natively e.g. on Ubuntu apt-get install docker.io curl -sSL https://get.docker.com/ubuntu — sh Mac / Windows run under VirtualBox http://boot2docker.io Docker Machine - https://github.com/docker/machine docker machine -d virtual-box dev docker machine -d openstack test docker machine -d softlayer ... prod Verify .. $ docker version Client/Server: Version: 1.9.1 OS/Arch: linux/amd64 .. your installation $ docker info Client/Server: Version: 1.9.1 OS/Arch: linux/amd64 Docker in practice 13/24

17. The Docker command line docker search Search for images in the docker hub docker pull Get a selected image from the docker hub docker images List all downloaded images docker run start a container docker ps List running images docker build Build an image from a Dockerﬁle docker start/stop/kill Containers management docker rm/rmi Remove a container / image Docker in practice 14/24

18. Run your ﬁrst container $ docker search ubuntu NAME DESCRIPTION STARS OFFICIAL A ubuntu Ubuntu is a Debian-based Linux operating s... 3132 [OK] [ ubuntu-upstart Upstart is an event-based replacement for... 61 [OK] [ $ docker pull ubuntu:latest latest: Pulling from library/ubuntu 92ec6d044cb3: Downloading 34.57 MB/65.68 MB Digest: sha256:457b0587384bdhuis83290....6db5ae3934307c757c54 Status: Downloaded newer image for ubuntu:latest $ docker images REPOSITORY TAG IMAGE ID CREATED VIRTUAL SIZE ubuntu latest 6cc0fc2a5ee3 1 minutes ago 187.9 MB chef-server latest f3cd15749fa8 21 months ago 1.043 GB $ docker run -i -t ubuntu /bin/bash root@e550480534b1:/# apt-get update && apt-get install -y nginx Docker in practice 15/24

22. The Dockerfile Dockerfile instruct on how to build the image automatically Dockerfile syntax: FROM RUN ENV EXPOSE ADD CMD $ docker build -t fmount/nginx . $ docker run -d -p 80 –name mystaticwebsite -v $PWD/website:/var/www/html/website fmount/nginx nginx Docker in practice 16/24

23. The Docker Hub It provides a mechanism to share images in the docker-hub, a repository of shareable collection of tagged images $ docker commit/login Exercise: Be Social :D Register in the Docker Hub Connect it to your Github and build Docker in practice 17/24

24. #Outline 1 Virtualization 2 Containers 3 Docker in practice 4 Docker Compose 5 Continuous integration Docker Compose 18/24

25. Get an app running in one command #!/ bin/python from flask import Flask from redis import Redis app = Flask(__name__) redis = Redis(host="localhost" , port =6379) @app.route("/") def hello (): redis.incr("hits") return "I have been seen %s times .n" % redis.get("hits") if __name__ == "__main__": app.run(host="0.0.0.0", debug= True) requirements.txt ﬂask package redis package Docker Compose 19/24

26. Get an app running in one command Steps to follow Write your Dockerﬁles Build your containers Prepare your application Think about the infrastructure Compose in a Microservices fashion Build and start the containers $ docker-compose up Docker Compose 20/24

27. #Outline 1 Virtualization 2 Containers 3 Docker in practice 4 Docker Compose 5 Continuous integration Continuous integration 21/24

28. Use case: Continuous Integration Continuous integration 22/24

29. Thank you! Questions? More examples at https://github.com/fmount/containers Continuous integration 23/24

30. References The Docker Book www.dockerbook.com How2dock https://github.com/how2dock/docbook Docker in Action https://www.manning.com/books/docker-in-action Oﬃcial doc https://docs.docker.com/ SlideShare Docker Channel http://www.slideshare.net/Docker/ Golang tour :D https://tour.golang.org/ Continuous integration 24/24