The document discusses virtual machines (VMs) versus containers for application deployment. It provides details on Linux containers (LXC), their benefits over VMs like speed and small footprint. The document then covers union file systems and control groups for resource management in containers. It notes that Docker provides a user-friendly interface to LXC and demonstrates basic Docker commands for pulling, running, and building containers.

1. Thiago Rondon, thiago@b-datum.com
Technical meeting b-datum
Monday, December 2, 13

2. VMs vs Containers
VM
App A App A’ App B
Guest
OS
Guest
OS
Guest
OS
Hypervisor (Type 2)
container
docker
Bin/libs Bin/libs Bin/libs
App App App App
A
A’
B
B’
Bin/libs
Host OS
SERVER
Monday, December 2, 13
Host OS
SERVER
Bin/libs

3. Containers
App A
App A’
Bin/libs
Original App
No OS to take
up space, resources,
or require restart.
Monday, December 2, 13
Copy of App
Modified App
No OS. Can share
/bin/libs
Union file system allows
us to only save the diffs.
Between container A
and container A’

4. LXC
“chroot() on steroids”
• LXC (LinuX Containers) let you run a
Linux system within another Linux system.
• a container is a group of processes on a
Linux box, put together in an isolated
environment.
• Inside the box, it look like a VM.
• Outside the box, it looks like a normal
processes.
Monday, December 2, 13

5. why LXC ?
• Speed - Fast boots, create VM, deploy tasks
• small footprint
• Virtualization - Own [net interface,fs]
• Isolation security and resources.
Monday, December 2, 13

6. AUFS
• Another Union File System
• Copy-on-write at the FS layer.
Monday, December 2, 13

7. Cgroup
• ulimit for groups of processes.
• limit, account and isolate resources.
• not perfect for limit I/O.
Monday, December 2, 13

8. Good example ?
• Do everything you do in VM, but fast!
• How many VMs do you need ?
• Continuous integration !!
Monday, December 2, 13

9. docker is user-friendly
interface to LXC.
Monday, December 2, 13

10. docker did all the
following...
•
•
•
•
•
•
•
•
Monday, December 2, 13
It downloaded the base image from the docker index
it created a new LXC container
It allocated a filesystem for it
Mounted a read-write layer
Allocated a network interface
Setup an IP for it, with network address translation
And then executed a process in there
Captured its output and printed it to you

11. Let’s rock.
•
•
•
•
•
Monday, December 2, 13
docker
search
ubuntu
docker
pull
ubuntu
docker
run
ubuntu
echo
“hello
b-­‐datum”
docker
run
ubuntu
apt-­‐get
install
-­‐y
memcached
docker
run
-­‐t
-­‐i
ubuntu
/bin/bash

12. Dockfile
#
just
for
test
FROM
ubuntu
RUN
apt-­‐get
install
-­‐y
memcached
MAINTAINER
Thiago
Rondon,
thiago@b-­‐datum.com
ENTRYPOINT
[“memcached”]
USER
daemon
EXPOSE
11211
docker build -t mymemcached - < MyDockFile
Monday, December 2, 13

13. docker exposes git-like commands for
comminting changes to running
containers.
Changes can be commited.
possible by AUFS.
Monday, December 2, 13

14. Images
•
•
•
•
•
Monday, December 2, 13
docker
ps
-­‐l
docker
commit
xxx
mystuff/memcached
docker
inspect
mystuff/memcached
docker
images
docker
push
mystuff/memcached

15. images & commits
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16. History
• docker history
• docker commit
• docker images -viz | dot -Tpng -o
docker.png
• docker images -tree
Monday, December 2, 13

17. Credits
• http://docker.io
Monday, December 2, 13