Start using Docker containers to build and scale your web apps

1. Web apps scaling with
Docker Ecosystem
Bohdan Sydor - DockerKRK meetup #2 - April 29, 2015

2. Ecosystem
Linux
Docker
Fig/Compose
Etcd
Confd
Nginx
LAMP
Python & Bash scripts
Ansible playbooks

3. Big Picture

4. What is Docker?
Sorry, not this time

5. Set up Docker host
KISS with Ansible

6. Fig/Compose
● Single host Docker orchestrator
● Manages configuration in YAML files
● YAML config can be templated by upper
level piece of software

7. Etcd
A highly-available key value store for shared
configuration and service discovery

8. Etcd core features
● Simple: curl'able user facing API
(HTTP+JSON)
● Secure: optional SSL client cert
authentication
● Fast: benchmarked 1000s of writes/s per
instance
● Reliable: properly distributed using Raft

9. Confd
● Lightweight configuration management tool
● Keeps local configuration files up-to-date
using data stored in etcd, [...]
● Reloads applications to pick up new config
file changes

10. Confd vs Nginx
● Confd watches etcd keys for upstream
servers
● Generates nginx config from template
● Reloads nginx

11. Simple Orchestrator
● Fig/Compose as the single host orchestrator
● Some Bash and Python scripting on top of
Fig
● Orchestrator keeps its configuration in Etcd
● Orchestrator cares about it’s local host
● The cluster state is available in Etcd

12. Build the app
● Use Dockerfiles to build your app
as Docker images
● You can automate the build process using
CI infrastructure (eg. Jenkins)

13. App image vs Etcd
/settings/app_image my_app:123
---
name: my_app
image: {{ app_image }}

14. Scaling Example
● /settings/hard_quota 100
/settings/min_instances 10
● docker ps | grep -c myapp_
● fig -p myapp -f myapp.yml scale web=10
● Combine all the items together using Bash,
Python, etc
● It’s simple and it works

15. Handling front traffic
● Nginx listens to client requests
● Request is rerouted to an upstream server
● Upstream server is a Docker container on
any host in the cluster
● Multiple Nginx instances could be behind
the load balancer

16. Need more?
● Simple example:
https://github.com/bsydor/docker-ossp
● Hands-on training
at Compendium Education Center:
http://www.compendium.pl/

17. Do you have any
questions?

18. Thank you
Bohdan Sydor
www.sydor.net
bsydor@gmail.com