docker off the grid
TRANSCRIPT
Copyright © 2015 Mirantis, Inc. All rights reserved
www.mirantis.com
Docker “Off the Grid”
Matthew MosesohnSenior Deployment Engineer
Copyright © 2015 Mirantis, Inc. All rights reserved
Agenda
● What are Docker images?● How to interact with Docker images?● Where it can go wrong...● When do you need a base image?● Building images for production● Distributing images...
● via tarball● via Docker Registry
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Docker Images
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What is in a Docker image?
● Base image● Additional image layers that stack on top of base● Metadata (links to layers and tags)
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Docker pull
Docker pull steps:● Fetch metadata● Fetch layers in parallel● Load images in order
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Think carefully
● 300mb+ uncompressed● Depends on external service● Depends on external build hosts● Depends on benevolent dictator
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Who is unaffected?
● Public cloud users● One time deployments with few changes● Demos/POCs
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Who should be concerned?
● Deployers of custom base images● Proprietary/unpublished code● Those concerned about bandwidth● Those with no direct Internet connection● Those concerned about consistency 24/7/365● Those who do CI/CD and need performance
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Where to start?
● Start with a base image● Take default centos:centos6 or ubuntu image● Or create your own base
● https://github.com/CentOS/sig-cloud-instance-images
● Keep it simple
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Heavy lifting
● Decide how to transport● Package and distribute
through APT or Yum● Distribute tarball via
HTTP/nfs/ftp● Use Docker Registry
● Build centrally or build on demand● Depends on target hosts
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Making the tarball
● Build your images (based on your base image)● docker save image1 image2 image3 > myimages.tar● Try lrzip for compression
● Faster than xz● Better compression than gzip/bzip2
● Try docker-squash to save more time (by Jason Wilder)● https://github.com/jwilder/docker-squash
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Going the Docker Registry route
● Still uncompressed, but local● Registry can be deployed as a container!
● docker pull docker/registry
● docker run -d -p5000:5000 -v /data/registry:/tmp/registry docker/registry
● docker tag myimage localhost:5000/myimage● docker push localhost:5000/myimage
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Pros and Cons of Docker Registry
● Pros:● Centralized store of Docker images● Lightweight app you can deploy anywhere● Native to Docker
● Cons:● Not highly available for local data stores
■ But with Amazon S3 or Glance it is decent
● Registry image is large
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Thank you
for your time