Daniel Farrell
Software Engineer, Red Hat SDN Team
Intro to Docker
Daniel Farrell
Red Hat SDN Team
VERY QUICK: INTRO TO ME
Daniel Farrell
Software Engineer, Red Hat SDN Team
VERY QUICK: INTRO TO ME
OpenDaylight Contributor
VERY QUICK: INTRO TO ME
OpenDaylight Integration Committer
Very Quick: Intro to ME
Other code!
VERY QUICK: INTRO TO ME
Robots!
VERY QUICK: INTRO TO ME
(Craft) Beer!
VERY QUICK: INTRO TO ME
Biking!
VERY QUICK: INTRO TO ME
SCUBA!
Goal
Very practical intro to using Docker
Overview
OVERVIEW
Lightweight, very fast containers
OVERVIEW
Consistent across dev, QA, production...
OVERVIEW
Deploy anywhere
OVERVIEW
Horizontal scaling
OVERVIEW
Layered file system -> huge wins
OVERVIEW
No hypervisor, so speed/isolation trade-off
OVERVIEW
Dockerfile -> docs and version control
LXC vs Docker
LXC VS DOCKER
Docker foundations have been in kernel for years
LXC VS DOCKER
LXC: sandboxing processes; controlling resource allocation
LXC VS DOCKER
Docker adds:
Portable deployments
LXC VS DOCKER
Docker adds:
Git-like versioning
LXC VS DOCKER
Docker adds:
"Base images"
LXC VS DOCKER
Docker adds:
Application-centric
LXC VS DOCKER
~Docker adds:
DockerHub
Dockerfiles
DOCKERFILES
Build from a base image
# Base the image on Debian 7
# Picked Debian because it's small (85MB)
# https://registry.hub.docker.com/_/debian/
FROM debian:7
DOCKERFILES
RUN cmds to customize
# Install required software (170MB)
RUN apt-get update && apt-get install -y openjdk-7-jre-headless wgetDOCKERFILES
You can set the CWD
WORKDIR /optDOCKERFILES
You can expose ports
EXPOSE 162 179 1088 1790 1830 2400 2550 2551 2552 4189 4342 5005 5666 6633 6640 6653 7800 8000 8080 8101 8181 8383 12001DOCKERFILES
Drop your project in the container with ADD
# Drop source (bot2014, current context) in /opt dir
# Do the ADD as late as possible, as it invalidates cache
ADD . /opt/bot
DOCKERFILES
Default process execution for container with CMD
CMD ["./bin/karaf", "server"]FS Layers
FS Layers
Docker uses a layered file system
FS LAYERS
Stack of RO layers with a RW layer on top
FS LAYERS
If nothing has changed about lower layers...
FS LAYERS
Caching! Speed! *Wins*!
FS LAYERS
[~/foss_rocks]$ time docker build -t dfarrell07/preanalytics:dev .
Sending build context to Docker daemon 343 kB
Step 0 : FROM debian:8.0
---> 835c4d274060
# Snip
Step 3 : ADD requirements.txt /tmp/requirements.txt
---> Using cache
---> 905a16f73f42
Step 4 : RUN pip install -r /tmp/requirements.txt
---> Using cache
---> f0af2258d85b
# Snip
Successfully built d3b3424b1313
docker build -t dfarrell07/preanalytics:dev . 0.01s user 0.01s system 7% cpu
FS Layers
Term: Images
Step 6 : WORKDIR /opt/preanalytics
---> Using cache
---> d3b3424b1313
Successfully built d3b3424b1313FS Layers
Term: Container
(overloaded)
1. The read/write layer on top
2. A running Docker thing
BUILDING IMAGES
Building Images
docker build [-t tag name] .
Building Images
docker build -t dfarrell07/opendaylight:dev .
BUILDING IMAGES
[~]$ docker images | tail -n 5
debian 8.0 835c4d274060 5 weeks ago 122.6 MB
debian jessie 835c4d274060 5 weeks ago 122.6 MB
fedora 21 834629358fe2 5 weeks ago 250.2 MB
fedora latest 834629358fe2 5 weeks ago 250.2 MB
dfarrell07/helium dev e5ece2a3040a 7 weeks ago 537.3 MB
Running containers
RUNNING CONTAINERS
[~]$ docker run -ti dfarrell07/helium:dev bash
root@97aec28eae4d:/opt/opendaylight#
RUNNING CONTAINERS
[~]$ docker run -ti dfarrell07/preanalytics:dev tox
# snip
Ran 160 tests in 26.513s
OK (skipped=4)
RUNNING CONTAINERS
[~/preanalytics]$ docker ps
CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES
bb6450f64015 dfarrell07/preanalytics:dev "bash" 26 minutes ago Up 26 minutes condescending_bell
Other Resources
Contact
Daniel Farrell
Twitter (optimal):
Others:
dfarrell@redhat.com
dfarrell07 on IRC, GitHub
Introduction to Docker
By Daniel Farrell
Introduction to Docker
Talk given at the NCSU LUG's 2015 FOSS Fair
