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Dockerizing Django projects Roberto Rosario robertorosario.com

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Who am I? robertorosario.com [email protected] Roberto Rosario

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What is Docker?

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Docker provides an integrated technology suite that enables development and IT operations teams to build, ship, and run distributed applications anywhere.

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In human now.

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Containers.

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Lightweight virtualization. ie: No video hardware emulation.

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Some devops now hate me.

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Deploy everywhere.

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Easy scalability.

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Even auto scaling.

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Deploying Django: Old school.

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Deployed! Congratulations!

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Your users have now quadrupled!

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Server are old, let’s go virtual!

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Different technology, same problem.

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Django and Docker?

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Configuration files.

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First steps.

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Classes Instances

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More devops hate me now.

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Dockerfile

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An entire OS for just a part of the Django project?

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Not to worry.

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Your Django project

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Your Django project

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Your Django project image Your Django project

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Base image = Base class Your image = Subclass

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Pretty much every devops hate me at this point.

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One size doesn’t fit all.

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Monolithic

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App Workers Web server

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docker run --name postgres -e POSTGRES_DB=mayan -e POSTGRES_USER=mayan -e POSTGRES_PASSWORD=mysecretpassword -v /var/lib/postgresql/data -d postgres docker run --name redis -d redis docker run --name mayan-edms -p 80:80 --link postgres:postgres --link redis:redis -e POSTGRES_DB=mayan -e POSTGRES_USER=mayan -e POSTGRES_PASSWORD=mysecretpassword -v /usr/local/lib/python2.7/dist- packages/mayan/media -d mayanedms/monolithic

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● Single download ● Low entry barrier ● Easiest to maintain ● Big size download ● Not good for scaling ● Same VM/Server problem

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Split

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App Workers Web server

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Split ~ Frontend + Backend

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● Scale individually ● Smaller download ● Best approach for production ● Harder to setup ● Need documentation ● Several DockerFiles

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Mixed

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Role Frontend Backend

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● Single download ● Can reuse configuration file templates ● Single core repo ● Bigger size download

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Lean

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Lean = Split without any 3rd party

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App Workers Web server

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● Smallest download ● Hardest to configure ● Might not scale best ● Might violate port export concept

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Django + uWSGI NGINX

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Django + uWSGI NGINX TCP Port uwsgi_pass 127.0.0.1:3031; socket = 127.0.0.1:3031

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Django + uWSGI NGINX socket = /tmp/uwsgi.sock uwsgi_pass unix:///tmp/uwsgi.sock; ?

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Django + uWSGI NGINX socket = /tmp/uwsgi.sock uwsgi_pass unix:///tmp/uwsgi.sock; Volume?

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● Need to include NGINX config

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$ docker run --name some-nginx -v /some/nginx.conf:/etc/nginx/nginx.conf:ro -d nginx

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environment: - NGINX_HOST=foobar.com - NGINX_PORT=80 command: /bin/bash -c "envsubst < /etc/nginx/conf.d/mysite.template > /etc/nginx/conf. d/default.conf && nginx -g 'daemon off;'"

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Last approach

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Kitchen sink

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App Workers Database Web server Broker

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● Single download ● Lowest entry barrier ● Biggest size download ● Terrible for scaling ● Same VM/Server problem ● Support 3rd party software

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Educational purposes only

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Don’t use in production

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EVER!

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Kitchen sink will freeze your servers

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Devops don’t like frozen servers

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Don’t turn your devops into Gordon Ramsay

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Post init actions

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migrate & collectstatic

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Service synchronization

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$ docker run --name postgres -e POSTGRES_DB=mayan -e POSTGRES_USER=mayan -e POSTGRES_PASSWORD=mysecretpassword -v /var/lib/postgresql/data -d postgres $ docker run --name redis -d redis $ docker run --name mayan-edms -p 80:80 --link postgres:postgres --link redis:redis -e POSTGRES_DB=mayan -e POSTGRES_USER=mayan -e POSTGRES_PASSWORD=mysecretpassword -v /usr/local/lib/python2.7/dist- packages/mayan/media -d mayanedms/monolithic

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Database connection error.

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$ docker run --name postgres -e POSTGRES_DB=mayan -e POSTGRES_USER=mayan -e POSTGRES_PASSWORD=mysecretpassword -v /var/lib/postgresql/data -d postgres $ docker run --name redis -d redis $ docker run --name mayan-edms -p 80:80 --link postgres:postgres --link redis:redis -e POSTGRES_DB=mayan -e POSTGRES_USER=mayan -e POSTGRES_PASSWORD=mysecretpassword -v /usr/local/lib/python2.7/dist- packages/mayan/media -d mayanedms/monolithic

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$ docker run --name postgres -e POSTGRES_DB=mayan -e POSTGRES_USER=mayan -e POSTGRES_PASSWORD=mysecretpassword -v /var/lib/postgresql/data -d postgres $ docker run --name redis -d redis $ docker run --name mayan-edms -p 80:80 --link postgres:postgres --link redis:redis -e POSTGRES_DB=mayan -e POSTGRES_USER=mayan -e POSTGRES_PASSWORD=mysecretpassword -v /usr/local/lib/python2.7/dist- packages/mayan/media -d mayanedms/monolithic until nc -z $POSTGRES_PORT_5432_TCP_ADDR $POSTGRES_PORT_5432_TCP_PORT; do echo "$(date) - waiting for postgres..." sleep 1 done

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Service synchronization doesn’t belong in configuration files.

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until nc -z $POSTGRES_PORT_5432_TCP_ADDR $POSTGRES_PORT_5432_TCP_PORT; do echo "$(date) - waiting for postgres..." sleep 1 done until nc -z $RABBITMQ_PORT_5672_TCP_ADDR $RABBITMQ_PORT_5672_TCP_PORT; do echo "$(date) - waiting for rabbitmq..." sleep 1 done

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More problems.

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● Not foolproof ● Mute services ● nc is not universal ● API URL paths?

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Solutions?

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$ docker run -d --name mycontainer some-image-or-other $ docker run --link mycontainer:mycontainer aanand/wait waiting for TCP connection to 172.17.0.105:5432......ok

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Interesting, but...

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An entire container to run nc.

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Cool solution, wrong problem.

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It’s the container manager’s responsibility.

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Kubernetes approach

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Port, path, initial delay & timeout!

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Docker upstream native approach needed

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Templating

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Docker images are static. Less reusable.

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Docker containers are configured with environment variables.

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uWSGI support environment variables. NGINX doesn’t.

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Docker upstream native approach needed

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“Thank you for using Docker” “But your fix is in another repository”

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Options?

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And then there is genius

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Bonus

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Can help with logs too

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Demo time

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Lessons learned?

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Thank you!