How to scale Docker containers in production - scale

Question

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So I recently discovered this awesome tool, and it says
Docker is an open-source project to easily create lightweight,
portable, self-sufficient containers from any application. The same
container that a developer builds and tests on a laptop can run at
scale, in production, on VMs, bare metal, OpenStack clusters, public
clouds and more.
Let's say I have a docker image which runs Nginx and a website connects to external database. How do I scale the container in production?

Answer 1

Update: 2019-03-11
First of all thanks for those who have upvoted this answer over the years.
Please be aware that this question was asked in August 2013, when Docker was still a very new technology. Since then: Kubernetes was launched on June 2014, Docker swarm was integrated into the Docker engine in Feb 2015, Amazon launched it's container solution, ECS, in April 2015 and Google launched GKE in August 2015. It's fair to say the production container landscape has changed substantially.
The short answer is that you'd have to write your own logic to do this.
I would expect this kind of feature to emerge from the following projects, built on top of docker, and designed to support applications in production:
flynn
deis
coreos
Mesos
Update 1
Another related project I recently discovered:
maestro
Update 2
The latest release Openstack contains support for managing Docker containers:
Docker Openstack
Paas zone within OpenStack
Update 3
System for managing Docker instances
Shipyard
And a presentation on how to use tools like Packer, Docker and Serf to deliver an immutable server infrastructure pattern
FutureOps with Immutable Infrastructure
Slides
Update 4
A neat article on how to wire together docker containers using serf:
Decentralizing Docker: How to use serf with Docker
Update 5
Run Docker on Mesos using the Marathon framework
Mesosphere Docker Developer Tutorial
Update 6
Run Docker on Tsuru as it supports docker-cluster and segregated scheduler deploy
http://blog.tsuru.io/2014/04/04/running-tsuru-in-production-scaling-and-segregating-docker-containers/
Update 7
Docker-based environments orchestration
maestro-ng
Update 8
decking.io
Update 9
Google kubernetes
Update 10
Redhat have refactored their openshift PAAS to integrate Docker
Project Atomic
Geard
Update 11
A Docker NodeJS lib wrapping the Docker command line and managing it from a json file.
docker-cmd
Update 12
Amazon's new container service enables scaling in the cluster.
Update 13
Strictly speaking Flocker does not "scale" applications, but it is designed to fufil a related function of making stateful containers (running databases services?) portable across multiple docker hosts:
https://clusterhq.com/
Update 14
A project to create portable templates that describe Docker applications:
http://panamax.io/
Update 15
The Docker project is now addressing orchestration natively (See announcement)
Docker machine
Docker swarm
Docker compose
Update 16
Spotify Helios
See also:
https://blog.docker.com/tag/helios/
Update 17
The Openstack project now has a new "container as a service" project called Magnum:
https://wiki.openstack.org/wiki/Magnum
Shows a lot of promise, enables the easy setup of Docker orchestration frameworks like Kubernetes and Docker swarm.
Update 18
Rancher is a project that is maturing rapidly
http://rancher.com/
Nice UI and strong focus on hyrbrid Docker infrastructures
Update 19
The Lattice project is an offshoot of Cloud Foundry for managing container clusters.
Update 20
Docker recently bought Tutum:
https://www.docker.com/tutum
Update 21
Package manager for applications deployed on Kubernetes.
http://helm.sh/
Update 22
Vamp is an open source and self-hosted platform for managing (micro)service oriented architectures that rely on container technology.
http://vamp.io/
Update 23
A Distributed, Highly Available, Datacenter-Aware Scheduler
https://www.nomadproject.io/
From the guys that gave us Vagrant and other powerful tools.
Update 24
Container hosting solution for AWS, open source and based on Kubernetes
https://supergiant.io/
Update 25
Apache Mesos based container hosted located in Germany
https://sloppy.io/features/#features
And Docker Inc. also provide a container hosting service called Docker cloud
https://cloud.docker.com/
Update 26
Jelastic is a hosted PAAS service that scales containers automatically.

Answer 2

Deis automates scaling of Docker containers (among other things).
Deis (pronounced DAY-iss) is an open source PaaS that makes it easy to deploy and manage applications on your own servers. Deis builds upon Docker and CoreOS to provide a lightweight PaaS with a Heroku-inspired workflow.
Here is the developer workflow:
deis create myapp # create a new deis app called "myapp"
git push deis master # built with a buildpack or dockerfile
deis scale web=16 worker=4 # scale up docker containers
Deis automatically deploys your Docker containers across a CoreOS cluster and configures the Nginx routers to route requests to healthy Docker containers. If a host dies, containers are automatically restarted on another host in seconds. Just browse to the proxy URL or use deis open to hit your app.
Some other useful commands:
deis config:set DATABASE_URL= # attach to a database w/ an envvar
deis run make test # run ephemeral containers for one-off tasks
deis logs # get aggregated logs for troubleshooting
deis rollback v23 # rollback to a prior release
To see this in action, check out the terminal video at http://deis.io/overview/. You can also learn about Deis concepts or jump right into deploying your own private PaaS.

Answer 3

You can try Tsuru. Tsuru is a opensource PaaS inspired in Heroku, and it is already with some products in production at Globo.com(internet arm of the biggest Broadcast Television Company in Brazil)
It manages the entire flow of an application, since the container creation, deploy, routing(with hipache) with many nice features as docker cluster, scaling of units, segregated deploy, etc.
Take a look in our documentation bellow:
http://docs.tsuru.io/
Here our post covering our environment:
http://blog.tsuru.io/2014/04/04/running-tsuru-in-production-scaling-and-segregating-docker-containers/

Answer 4

Have a look at Rancher.com - it can manage multiple Docker hosts and much more.

Answer 5

A sensible approach to scaling Docker could be:
Each service will be a docker container
Intra container service discovery managed through links (new feature from docker 0.6.5)
Containers will be deployed through Dokku
Applications will be managed through Shipyard which in its turn is using hipache
Another docker open sourced project from Yandex:
cocaine

Answer 6

Openshift guys also created a project. You can find more information here, try test container and detailed info here .
The only problem is the solution is Redhat centric for now :)

Answer 7

While we're big fans of Deis (deis.io) and are actively deploying to it, there are other Heroku like PaaS style deployment solutions out there, including:
Longshoreman from the Wayfinder folks:
https://github.com/longshoreman/longshoreman
Decker from the CloudCredo folks, using CloudFoundry:
http://www.cloudcredo.com/decker-docker-cloud-foundry/
As for straight up orchestration, NewRelic's opensource Centurion project seems quite promising:
https://github.com/newrelic/centurion

Answer 8

Take a look also at etcd and Consul.

Answer 9

Panamax: Docker Management for Humans. panamax.io
Fig: Fast, isolated development environments using Docker. fig.sh

Answer 10

One option not mentioned in other posts is Helios. It is built by spotify and does not try to do too much.
https://github.com/spotify/helios