CI with Docker and Jenkins

Francesco Bruni

Club degli sviluppatori - Bari, May ‘19

@brunifrancesco

Who am I•MSc Telecommunication Engineer @ Poliba •Despite a Java background, I prefer Python whenever

possible •I'm not a computer scientist

Continuous Integration•Keep integrating multiple times a day the central code

repository; •Run as more tests as you can to ensure nothing broke

down; •Be ready to replicate environment.

Why CI matters•Continuous testing/building for all teammates; •Let someone do trivial jobs.

CI advantage

“Continuous Integration doesn’t get rid of bugs, but it does make them

dramatically easier to find and remove” M. Fowler

CI requirements•Single source repo; •Automated building; •Self testing build; •Build fast; •Run tests in a production env clone; •Automate deployment.

CI cycle

Develop Feature

Integrate in the main code baseTest/build/label

Checkout codeCorrect detected

iussues

CI and TDD

TDD

CI

CI cycle•Integrating code should be automated; •Multiple levels testing; •Devs must not checkout bugged code; •Devs must not deploy untested code;

CI drawbacks•Setting files; •Setting all the stuff up requires time and patience.

CI natural evolution: Continuous Delivery

•If a commit builds (all tests succeed), deliver it; •Keep delivery time at minimum; •Multiple deliveries for multiple versions.

Know your tools•Test everything; •Keep your sources/setting files versioned; •Containerize everything; •Automate as much as you can.

Test everything•Test your sources, checking coverage; •Test for writing new features; •Test your application settings; •If you want to deliver software, check external

requirements.

Smarter use of VCs•Keep code versioned: application settings/sources/dep

indexes; •Keep env settings versioned: scripts and configuration

files; •Enjoy version control well defined ‘flows’ :)

Be containerized•Develop solutions in well separated envs; •Ship software as main part of env; •Don’t play with global deps. •‘Restore’ basic envs to speed up env creation process.

What’s Docker•Wrap many services in many

containers; •Create, play with and destroy

containers; •Save and easily replicate

isolated containers.

Dockerfiles# pull base image. FROM java:8

# maintainer details MAINTAINER Francesco Bruni "francesco.bruni@stasbranger.com"

# update packages and install maven RUN \ export DEBIAN_FRONTEND=noninteractive && \ sed -i 's/# \(.*multiverse$\)/\1/g' /etc/apt/sources.list && \ apt-get update && \ apt-get -y upgrade && \ apt-get install -y vim wget curl git maven ssh nano python-pip # attach volumes VOLUME /volume/git

# create working directory and set some stuff up RUN mkdir -p /local/git WORKDIR /local/git RUN mkdir -p /root/.ssh ADD id_rsa /root/.ssh/id_rsa RUN chmod 700 /root/.ssh/id_rsa RUN echo "Host <ip>\n\tStrictHostKeyChecking no\n" >> /root/.ssh/config COPY .m2 /root/.m2 COPY run.sh run.sh RUN chmod a+x run.sh

# run this when container starts CMD ["./run.sh"]

Automate procedures•Repetitive tasks should be performed by automated

agents; •Once you teach the agent what to do, it’s up to him to

fulfill the job.

What’s Jenkins•Automated procedures worker; •Run tasks, report final status,

log activities; •Multiple plugin for multiple

features; •Use it just for playing too :)

Deploy w/ Docker w/o Jenkins

•Test code (or at least run a set of tests); •Push code to repo; •SSH in the server, enter in container; •Pull changes and restart required services. •Check if it works! :)

Practical session•Integrate new code into the

main branch; •Test all the stuff; •Deploy it :)

What we’ll need•A GIT web hook; •Set private “credentials”; •A tool to test configuration settings; •A container to run the test suite; •A container to run the new application; •A pipeline.

GIT web hook• Bind an action (tipically run a script) to GIT events; • Notify Jenkins new code has been pushed over the

‘develop’ branch.

#! /bin/bash

read oldrev newrev _branch tail=$(git log -1 --pretty=format:'%h %cn: %s%b' $newrev) curl http://<ip>:8080/job/QW/build?token=vH3YKmrRR5KOT4aeAOAV&commitMessage=$tail&cause=JenkinsDeploy

Merge/Test configurations

import osmain_path = os.path.join("src", "main","resources","application.properties")test_path = os.path.join("src", "test","resources","application.properties")for element in (main_path, test_path,): with open(element) as old_main: data = map(lambda line: line.strip(), old_main.readlines()) data[6] = data[6].replace("192.168.1.75", "mysql") data[6] = data[6].replace("<myIp>", "mysql") with open(element, "wb") as new_main: new_main.write(“\n".join(data))

Connection().quick_connect("user", "password", “db_test", "<myIp>") Connection().quick_connect("user", "password", "db", "mysql")

Create the container to run test suite

Run tests and see if they fails :)

Deploy the new version

• Create the new container and run the new version; • The new container should replace an existing one.

Going on productionNo way, do some manual testing and start a new CD build

All togheternode { stage 'Stage 1' sh 'docker run --rm --link mysqlC:mysql --name sms-checklink-container sms-checklink' stage 'Stage 2' sh 'docker rm -f sms-test-container || echo \'no container to delete\'' sh 'docker run --rm --name sms-test-container --link mysqlC:mysql sms-test' stage 'Stage 3' sh 'docker run --rm --name sms-merge-container sms-merge' stage 'Stage 4' sh 'docker rm -f sms-staging-container || echo \'no container to delete\'' sh 'docker run -d -p 8433:8080 --name sms-staging-container --link mysqlC:mysql sms-staging' }

Conclusions• Improve configuration settings handling; • Reduce testing time; • Bind Jenkins job to commit messages; • Improve git-flow integration; • Docker Compose :( • Deploy project on production via manual tests.

References

Continuous Delivery Reliable Software Releases through Build, Test, and Deployment Automation

by Jez Humble and David Farley

Continuous Integration

by Martin Fowler http://martinfowler.com/articles/continuousIntegration.html

References

Docker for beginners

https://scotch.io/tutorials/getting-started-with-docker

Meet Jenkins https://wiki.jenkins-ci.org/display/JENKINS/Meet+Jenkins

Docker Explained: Using Dockerfiles to Automate Building of Images

https://www.digitalocean.com/community/tutorials/docker-explained-using-dockerfiles-to-automate-building-of-images

Let’s see it @ work

Questions?@brunifrancesco