Docker Advanced registry usage by Joffrey Fuhrer at the Docker Freiburg meetup #1

1. Docker: Advanced
registry usage
September 17th, 2014 in Freiburg

2. Contents
1. What’s a registry?
2. Advanced configuration
a. Search index
b. Mirroring
c. Adding a redis cache
d. More!
3. Extending the code

3. What’s a registry?
• Storage component for docker images
• Open-source python app
• docker/docker-registry on github
• Current stable version: 0.8.1
• Available as an official image
docker run -d -p 5000:5000 registry:0.8.1

4. What’s a registry?
• Several storage backends supported
• Filesystem
• Boto (S3, Google Compute, ...)
• OpenStack Swift

5. Advanced configuration
The registry image is great for quick setup and testing, but
we can make it even better with some tinkering!
• Enabling search
• Mirroring another registry (even the official one!)
• Adding a redis cache
• And more!

6. Search index
Enabling a basic search index is easy!
docker run -d -p 5000:5000 -e
SEARCH_BACKEND=sqlalchemy registry:0.8.1

7. Search index
Let’s put our SQLite database in a volume.
docker run -d -p 5000:5000
-e SEARCH_BACKEND=sqlalchemy
-e SQLALCHEMY_INDEX_DATABASE=sqlite:////opt/sqlitedb/reg.db
-v /opt/sqlitedb:/opt/sqlitedb
registry:0.8.1

8. Search index
Also, we want to keep our image store persistent across
restarts!
docker run -d -p 5000:5000
-e SEARCH_BACKEND=sqlalchemy
-e SQLALCHEMY_INDEX_DATABASE=sqlite:////opt/sqlitedb/reg.db
-e STORAGE_PATH=/opt/registry
-v /opt/registry/storage:/opt/registry
-v /opt/sqlitedb:/opt/sqlitedb
registry:0.8.1

9. Search index
This is quite a mouthful... Let’s make a Dockerfile instead.
$ docker build -t myregistry .
$ docker run -d -p 5000:5000 -v
/opt/registry/storage:/opt/registry -v
/opt/registry/index:/opt/sqlitedb myregistry
That’s better!

10. Search index
Don’t like SQLite? That’s fine too!

11. Mirroring
Having a local copy of commonly used images can be very
helpful!

12. Mirroring
“Standard“ method:
$ docker pull busybox:latest
$ docker tag busybox:latest myregistry.
com/busybox:latest
$ docker push myregistry.com/busybox:latest
$ docker pull busybox:buildroot-2014.02
...

13. Mirroring
Better method: Enable mirroring on your registry!
ENV MIRROR_SOURCE https://registry-1.docker.io
ENV MIRROR_SOURCE_INDEX https://index.docker.io

14. Mirroring
• On the first pull, immutable data (metadata, layers,
image ancestry) is stored locally on the mirror.
• The source is always contacted to retrieve mutable data
(list of tags, <tag / image ID> mappings)...
• ... unless you enable the redis cache, then tag data is
kept for some time.
• Set MIRROR_TAGS_CACHE_TTL accordingly!

15. Adding a redis cache
First let’s start up a redis container.
$ docker run --name rediscache -d redis:2.8.13
Then we’re going to edit config/config_sample.yml
cache:
host: _env:REDISCACHE_PORT_6379_TCP_ADDR
port: _env:REDISCACHE_PORT_6379_TCP_PORT
db: 0
cache_lru:
host: _env:REDISCACHE_PORT_6379_TCP_ADDR
port: _env:REDISCACHE_PORT_6379_TCP_PORT
db: 1

16. Adding a redis cache
• Copy the config_sample.yml file where our Dockerfile
from before is.
• Add the following line to our Dockerfile:
ADD ./config_sample.yml /docker-registry/
config/config_sample.yml
• Create a link with our rediscache container when
starting up the registry
docker run -d -p 5000:5000 --link rediscache:rediscache
-v /opt/registry/storage:/opt/registry -v
/opt/registry/index:/opt/sqlitedb myregistry

17. Adding a redis cache
• Create a link with our rediscache container when
starting up the registry
docker run -d -p 5000:5000 --link rediscache:rediscache
-v /opt/registry/storage:/opt/registry -v
/opt/registry/index:/opt/sqlitedb myregistry
• All set!

18. More configuration!
• Use an nginx or Apache frontend to enforce basic auth.
• You can then do: docker login my.registry.com
• Only works over HTTPS!
• Enable e-mail notifications when an exception is
encountered
• See the email_notifications section of the
configuration

19. Extending the code
• You’ll need time and some Python proficiency.
• But for advanced usage, it can be worth it!
• If you make something cool, think about giving back to the
community! We accept pull requests.

20. Extending the code
• You can implement a new storage driver by inheriting
docker_registry.core.driver.Base
• Leverage the signals API in docker_registry.lib.signals
• Implement a new search backend by inheriting
docker_registry.lib.index.Index
• Other ideas? Talk to us, let us know if we can help!

21. • Code: github.com/docker/docker-registry
• DockerHub: registry.hub.docker.com/_/registry
• Contact me:
• Twitter @j0ffrey
• GitHub @shin-
• E-mail joffrey@docker.com
THANK YOU!
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