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copyright 2014 1 Docker and the end of the distro Chris Swan, CTO @cpswan Cloud native networking
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copyright 2014 1
Docker and the end of the distro
Chris Swan, CTO @cpswan
Cloud native networking
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TL;DR A great part of the Docker success story has been reuse of existing distros This is a bad thing, and we can do better We’ve already done something for what we run Docker on. Next up – what we run in Docker
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Docker runs just fine in/on
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So quite often host OS == container OS
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Host
Container Container Container
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We don’t need a full OS to run Docker
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So now we have host OS < container OS
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Host
Container Container Container
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What we run Docker on != what we run in Docker
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So we can’t easily get this
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Host
Container Container Container
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But we don’t need a full OS inside containers
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But we might aspire to this
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Host
Container Container Container
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The manifest problem
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A typical Dockerfile
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Each active line creates a layer
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Base OS Sources
Update repos Install nginx
Mod nginx.conf Mod index.html
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An image binds layers together
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Base OS Sources
Update repos Install nginx
Mod nginx.conf Mod index.html
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Nginx example
The image is the unit of deployment
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Nginx example
What version of nginx is that?
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Nginx example
What version of OpenSSL installed?
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?
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Nginx example
and which bash?
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?
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Problem 1 – non determinism
Whilst we want this to be cached in the short term: apt-get install nginx We perhaps don’t want it cached in the long term
What are those durations?
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Dockerfile Jenga
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CC Image credit: Ed Garcia https://www.flickr.com/photos/egarc2/2432270195
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2 – the manifest problem
When I run apt-get install nginx
I don’t know which version of nginx I just got
Should I? nginx –v > some_log.txt
Or maybe? apt-cache policy nginx > some_log.txt
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Recommendation 2 (of 6)
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Get specific:
But… might still pull in a bunch of point in time dependencies
Check out http://container-solutions.com/2014/11/6-dockerfile-tips-official-images/ (http://is.gd/sixtips)
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Solomon promises to fix things
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FROM scratch
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There is another way
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TL;DR A great part of the Docker success story has been reuse of existing distros This is a bad thing, and we can do better We’ve already done something for what we run Docker on. Next up – what we run in Docker
