DOCKEr + torrenT = Docket
Docket is a custom docker registry that allows for deployments through bittorrent. It allows for lightning fast Docker image deploys across large number of machines.
This was designed and built in 48 hours as part of the Gopher Gala Golang 48 hour hackathon. Hence kindly forgive me for the hackish code, and lack of tests.
[On hind sight - container rush or docker flood would have been a better name.]
As containers get more mainstream, server deployments are soon going to be done through a containerization solution like docker [or rocket or lxd].
Large scale deploys are going to choke your docker registry. Imagine pulling/deploying a 800mb base image (for example the official perl image) across 200 machines in one go. That's 800*200 = 160GB of data that's going to be deployed and it'll definitely choke your private docker registry (and will take a while pulling in from the public image)
The solution is BitTorrent. Any technology good for distributing music and movies, is usually good for doing server deploys. Instead of downloading from one point source, we can now distribute the load across the machines downloading themselves. All of this transparently and automatically handled by the docket client.
Silly Totally Non-scientific Benchmark
Pulling a 800 mb image across 5 machines simultaneously via Docket resulted in a 90% speedup.
- Written in Golang :)
- Very easy to use
- Works along side your private docker registry
Docket constitutes of 3 components:
- Docket Registry
A REST service that acts as a registry. It receives docker image tarballs from the client, stores metadata into a database, creates torrents out of them and seeds them.
- Docket Client
The client itnerface in which the end user will be interacting. Can view available images in the registry, push an image to the registry and pull an image (which triggers a bittorrent deploy) from the registry.
- Bittorrent Tracker
Docket allows you to BYOT (bring your own tracker), but I suggest installing opentracker
Docket uses ctorrent for the actual downloading of torrents.
Step 0: You need to already have Docker installed
Step 1: Install ctorrent and opentracker
$ sudo apt-get update $ sudo apt-get install zlib1g-dev make g++ ctorrent $ git clone https://github.com/gebi/libowfat $ make $ git clone git://erdgeist.org/opentracker $ cd opentracker $ make
Step 2: Download the Docket binaries
$ wget http://storage.googleapis.com/docket/docket.zip $ unzip docket.zip
Step 3: That's all
Step 1: Fire up the Tracker
$ cd opentracker $ ./opentracker 8940
Step 2: Fire up the Registry
$ cd registry # Note you need to put an ip address in which other machines can contact the tracker # You cannot put in localhost or 127.0.0.1 $ sudo ./registry --tracker "10.240.101.85:8940"
Push an image to the Registry
$ cd client #Note: You will have to to explicitly mention the tag ":latest" $ sudo ./client -h "http://10.240.101.85" push netvarun/test:latest Found image: netvarun/test:latest ID: 353b94eb357ddb343ebe054ccc80b49bb6d0828522e9f2eff313406363449d17 RepoTags: [netvarun/test:latest] Created: 1422145581 Size: 0 VirtualSize: 188305056 ParentId: d7d8be71d422a83c97849c4a8e124fcbe42170d5ce508f339ce52be9954dc3b4 Exporting image to tarball... Successively exported tarball... key = image val = netvarun/test:latest key = id val = 353b94eb357ddb343ebe054ccc80b49bb6d0828522e9f2eff313406363449d17 key = created val = 1422145581 Successfully uploaded image: netvarun/test:latest to the Docket registry.
List all images available in the Registry
$ cd client $ sudo ./client -h "http://10.240.101.85" images netvarun/test:latest perl:latest
Do a deploy
$ cd client $ sudo ./client -h "http://10.240.101.85" pull perl:latest Downloading the torrent file for image: perl:latest Downloading from the torrent file... META INFO Announce: http://10.240.101.85:8940/announce Piece length: 524288 Created with: docket-registry FILES INFO <1> 14f61693dd2db6380755a662d6e4e3583b5214fad9032bd983ce6c70df2144bc_perl_latest.tar  Total: 799 MB Found bit field file; verifying previous state. Listening on 0.0.0.0:2706 Press 'h' or '?' for help (display/control client options). Checking completed. - 0/0/1 [0/1600/0] 0MB,0MB | 0,0K/s | 0,0K E:0,0 Connecting End of input reached. Input channel is now off \ 1/0/2 [1572/1600/1600] 785MB,0MB | 36422,0K/s | 38896,0K E:0,1 Download complete. Total time used: 0 minutes. Seed for others 0 hours | 0/0/2 [1600/1600/1600] 799MB,0MB | 0,0K/s | 14320,0K E:0,1 Connecting Tarball path = /tmp/docket/14f61693dd2db6380755a662d6e4e3583b5214fad9032bd983ce6c70df2144bc_perl_latest.tar Exporting image to tarball...
Reference (Docket Registry)
./registry --help usage: registry [<flags>] Docket Registry Flags: --help Show help. -t, --tracker="10.240.101.85:8940" Set host and port of bittorrent tracker. Example: -host 10.240.101.85:8940 Note: This cannot be set to localhost, since this is the tracker in which all the torrents will be created with. They have to be some accessible ip address from outside -p, --port="8000" Set port of docket registry. -l, --location="/var/local/docket" Set location to save torrents and docker images.
Reference (Docket Client)
./client usage: client [<flags>] <command> [<flags>] [<args> ...] Docket Client Flags: --help Show help. -h, --host="http://127.0.0.1" Set host of docket registry. -p, --port="8000" Set port of docket registry. -l, --location="/tmp/docket" Set location to store torrents and tarballs. Commands: help [<command>] Show help for a command. push <push> Push to the docket registry. pull <pull> pull to the docket registry. images [<flags>] display images in the docket registry.
Sivamani Varun (firstname.lastname@example.org)