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Taking Control of Chaos with Docker and Puppet
The document discusses using Docker and Puppet for managing applications through containerization, highlighting benefits like isolation, security, and ease of deployment. It details personal experiences managing a server with multiple responsibilities, emphasizing the importance of immutable instances and compartmentalization of services. The author shares insights on building and managing containers, addressing challenges faced with Docker, while proposing future enhancements and collaboration on open-source modules.
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Taking Control of Chaos with Docker and Puppet
- 2. Taking control ofchaos (with Docker and puppet) - Tomas Doran @bobtfish 18/11/2013
- 3. Docker - whyshould you care? • Isolation – Run each daemon in it’s own container • Security – Containers are fully independent – Build a new container for a new application version! • Ease of development – Same containers in Vagrant on laptop as in production! – Build pipeline for whole application environment • Ease of deployment – Deploy from your own private registry – Roll back by just deploying the last version
- 4. Taking control ofchaos • My personal server • Lots of responsibilities – – – – – – Postfix Dovecot DNS Irc + tmux tor A zillion web apps (ruby, perl, php, python, nodejs!) • 0 time spent on it
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- 6. Several years later…. Labelfor your image (if needed) $864
- 7. Reality Label for yourimage (if needed) $864
- 8. This year’s model Labelfor your image (if needed) $864
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- 10. Convergence and immutability •Exactly one run – Should be building machines clean every time – Doing exactly one puppet run • Always rebuild – Unless you rebuild regularly – You don’t know you can rebuild • Immutable instances – Never change config on a server, replace instance! • Hard if you only have 1 server!
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- 20. For real. $864 Postfix Dovecot Postgrey SpamassasinMysql irssi playground (sshd)
- 21. A cunning plan •Build puppet code for installing service on the old server • Run same puppet code inside a container to install packages / build config • Add shims to start service inside container
- 22. Data management • Allmutable data is an lvm volume mounted from the host • All lvm volumes also get bind mounted read only • Share unix domain sockets this way • Server for socket creates • Clients mount ro version
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- 25. What’s inside acontainer? supervisord: • The ‘real’ process • mcollective • sshd
- 26. Code structure • profile::dovecot –All the things needed to run dovecot – Parameterizeable as needed for two different deploy environments. • container::dovecot – Main entry point when building the container – Delegates most of real setup to profile::dovecot – Adds all the container specific overrides – Adds supervisor service(s) for this container • run_container::dovecot – Wraps docker::run {} – Manages the associated lvm volumes – Adds firewall rules
- 27. profile::dovecot ! – All thethings needed to run dovecot – Parameterizeable as needed for two different deploy environments.
- 28. container::dovecot ! – Main entrypoint when building the container – Delegates most of real setup to profile::dovecot – Adds all the container specific overrides – Adds supervisor service(s) for this container
- 29. run_container::dovecot ! – Wraps docker::run{} – Manages the associated lvm volumes – Adds firewall rules
- 30. Building containers • profile::docker::build_container –define - writes out Dockerfile + support files – Runs docker build . – Manages dependencies so base containers get built first • profile::docker::with_socket::mysql – /socket/mysql – Symlink into /var/lib/mysql • profile::docker::with_supervisord – Setup supervisor with default (mcollective + ssh) tasks – Default /start script to invoke supervisord
- 31. profile::docker::build_container ! – define -writes out Dockerfile + support files – Runs docker build . – Manages dependencies so base containers get built first
- 32. profile::docker::build_container ! – define -writes out Dockerfile + support files – Runs docker build . – Manages dependencies so base containers get built first
- 33. profile::docker::build_container ! – define -writes out Dockerfile + support files – Runs docker build . – Manages dependencies so base containers get built first
- 34. container::with_socket::mysql – /socket/mysql – Symlinkinto /var/lib/mysql
- 35. container::with_supervisord ! – Setup supervisorwith default (mcollective + ssh) tasks – Default /start script to invoke supervisord
- 36. The Dockerfile • Dropfacts – /etc/facter/facts.d/is_container.txt – /etc/facter/facts.d/container_name • Copy in code – ADD support/puppet /etc/puppet • Run puppet – Masterless – No real manifest, just: if $::is_container {..
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- 38. Drop facts – /etc/facter/facts.d/is_container.txt ! ! ! ! ! ! –/etc/facter/facts.d/container_name.txt
- 39. Puppet code – ADDsupport/puppet /etc/puppet – RUN bundle exec rake puppet
- 40. site.pp – Masterless – Nonode manifest, just: if $::is_container {..
- 41. Issues • Docker iskinda buggy – Just went 1.0, being fixed fast! – No sane exit status to docker build – AUFS 42 layer limit • Forge modules + packages assume service management – No upstart inside containers - fails everywhere • Debian packages are inconsistent – Lots of packages don’t use invoke-rc.d
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- 43. Loads of TODOs •HAProxy all the things! – Currently just bind containers to local ports – Container replacement is not invisible – Run haproxy on the real host – Dynamically regenerate its config based on running containers • Registry – Build containers in Vagrant, push up to prod • PAAS web stuff – www all still lives on old server :( – Gonna fix this real soon
- 44. Open sores! • Opensource all the things! – garethr++ – (I owe you patches) – Forked and changed a million modules – Will cleanup and upstream some changes • My profile::docker code – Don’t know how to make this really generically reusable – We need sub-modules? – Happy to share chunks
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