docker
DESCRIPTION
DockerTRANSCRIPT
VMs vs Containers
SERVER
Host OS
Hypervisor (Type 2)
Guest OS
Bin/libs
Guest OS
Bin/libs
Guest OS
Bin/libs
App A App A’ App B
SERVER
Host OS
Bin/libs Bin/libs
App A
App A’
App B
App B’
dock
er
container
VM
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Containers
App A
Bin/libs
App A’
Original App Copy of App Modified App
No OS to takeup space, resources,or require restart.
No OS. Can share/bin/libs
Union file system allowsus to only save the diffs.
Between container A and container A’
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LXC
• 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.
“chroot() on steroids”
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why LXC ?
• Speed - Fast boots, create VM, deploy tasks
• small footprint
• Virtualization - Own [net interface,fs]
• Isolation security and resources.
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AUFS
• Another Union File System
• Copy-on-write at the FS layer.
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Cgroup
• ulimit for groups of processes.
• limit, account and isolate resources.
• not perfect for limit I/O.
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Good example ?
• Do everything you do in VM, but fast!
• How many VMs do you need ?
• Continuous integration !!
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docker is user-friendly interface to LXC.
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docker did all the following...
• 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
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Let’s rock.
• 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
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Dockfile# just for testFROM ubuntuRUN apt-‐get install -‐y memcachedMAINTAINER Thiago Rondon, thiago@b-‐datum.com
ENTRYPOINT [“memcached”]USER daemonEXPOSE 11211
docker build -t mymemcached - < MyDockFile
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docker exposes git-like commands for comminting changes to running
containers.Changes can be commited.
possible by AUFS.
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Images
• docker ps -‐l
• docker commit xxx mystuff/memcached
• docker inspect mystuff/memcached
• docker images
• docker push mystuff/memcached
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images & commits
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History
• docker history
• docker commit
• docker images -viz | dot -Tpng -o docker.png
• docker images -tree
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