1. copyright 2014 1
Docker
and the end of the distro
Chris Swan, CTO
@cpswan
Cloud native networking

2. copyright 2014 2
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

3. copyright 2014
Docker runs just fine in/on
3

4. copyright 2014
So quite often
host OS == container OS
4
Host
Container Container Container

5. copyright 2014
We don’t need a full OS
to run Docker
5

6. copyright 2014
So now we have
host OS < container OS
6
Host
Container Container Container

7. copyright 2014
What we run Docker on
!= what we run in Docker
7

8. copyright 2014
So we can’t easily get this
8
Host
Container Container Container

9. copyright 2014
But we don’t need a full OS
inside containers
9

10. copyright 2014
But we might aspire to this
10
Host
Container Container Container

11. copyright 2014 11
The manifest problem

12. copyright 2014
A typical Dockerfile
12

13. copyright 2014
Each active line creates a layer
13
Base OS
Sources
Update repos
Install nginx
Mod nginx.conf
Mod index.html

14. copyright 2014
An image binds layers together
14
Base OS
Sources
Update repos
Install nginx
Mod nginx.conf
Mod index.html

15. copyright 2014
Nginx example
The image is the unit of deployment
15

16. copyright 2014
Nginx example
What version of nginx is that?
16

17. copyright 2014
Nginx example
What version of OpenSSL installed?
17
?

18. copyright 2014
Nginx example
and which bash?
18
?

19. copyright 2014
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?
19

20. copyright 2014
Dockerfile Jenga
20
CC Image credit: Ed Garcia https://www.flickr.com/photos/egarc2/2432270195

21. copyright 2014
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
21

22. copyright 2014
Recommendation 2 (of 6)
22
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)

23. copyright 2014
Solomon promises to fix things
23

24. copyright 2014
FROM scratch
24

25. copyright 2014
There is another way
25

26. copyright 2014 26
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

27. copyright 2014 27
Chicago, US
ContactMe@cohesiveft.com
+1 888 444 3962
Questions?