docker-api

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This gem provides an object-oriented interface to the Docker Remote API. Every method listed there is implemented. At the time of this writing, docker-api is meant to interface with Docker version 1.3.*

If you're interested in using Docker to package your apps, we recommend the dockly gem. Dockly provides a simple DSL for describing Docker containers that install as Debian packages and are controlled by upstart scripts.

Installation

Add this line to your application's Gemfile:

gem 'docker-api', :require => 'docker'

And then run:

$ bundle install

Alternatively, if you wish to just use the gem in a script, you can run:

$ gem install docker-api

Finally, just add require 'docker' to the top of the file using this gem.

Usage

docker-api is designed to be very lightweight. Almost no state is cached (aside from id's which are immutable) to ensure that each method call's information is up to date. As such, just about every external method represents an API call.

Starting up

Follow the installation instructions, and then run:

$ sudo docker -d

This will daemonize Docker so that it can be used for the remote API calls.

If you're running Docker locally as a socket, there is no setup to do in Ruby. If you're not or change the path of the socket, you'll have to point the gem to your socket or local/remote port. For example:

Docker.url = 'tcp://example.com:5422'

Two things to note here. The first is that this gem uses excon, so any of the options that are valid for Excon.new are also valid for Docker.options. Second, by default Docker runs on a socket. The gem will assume you want to connect to the socket unless you specify otherwise.

Also, you may set the above variables via ENV variables. For example:

$ DOCKER_URL=unix:///var/docker.sock irb
irb(main):001:0> require 'docker'
=> true
irb(main):002:0> Docker.url
=> "unix:///var/docker.sock"
irb(main):003:0> Docker.options
=> {}
$ DOCKER_URL=tcp://example.com:1000 irb
irb(main):001:0> require 'docker'
=> true
irb(main):003:0> Docker.url
=> "tcp://example.com:1000"
irb(main):004:0> Docker.options
=> {}

Before doing anything else, ensure you have the correct version of the Docker API. To do this, run Docker.validate_version!. If your installed version is not supported, a Docker::Error::VersionError is raised.

Global calls

All of the following examples require a connection to a Docker server. See the Starting up section above for more information.

require 'docker'
# => true

Docker.version
# => { 'Version' => '0.5.2', 'GoVersion' => 'go1.1' }

Docker.info
# => { "Debug" => false, "Containers" => 187, "Images" => 196, "NFd" => 10, "NGoroutines" => 9, "MemoryLimit" => true }

Docker.authenticate!('username' => 'docker-fan-boi', 'password' => 'i<3docker', 'email' => 'dockerboy22@aol.com')
# => true

Images

Just about every method here has a one-to-one mapping with the Images section of the API. If an API call accepts query parameters, these can be passed as an Hash to it's corresponding method. Also, note that Docker::Image.new is a private method, so you must use .create, .build, .build_from_dir, build_from_tar, or .import to make an instance.

require 'docker'
# => true

# Create an Image.
image = Docker::Image.create('fromImage' => 'base')
# => Docker::Image { :id => ae7ffbcd1, :connection => Docker::Connection { :url => tcp://localhost, :options => {:port=>2375} } }

# Insert a local file into an Image.
image.insert_local('localPath' => 'Gemfile', 'outputPath' => '/')
# => Docker::Image { :id => 682ea192f, :connection => Docker::Connection { :url => tcp://localhost, :options => {:port=>2375} } }

# Insert multiple local files into an Image.
image.insert_local('localPath' => [ 'Gemfile', 'Rakefile' ], 'outputPath' => '/')
# => Docker::Image { :id => eb693ec80, :connection => Docker::Connection { :url => tcp://localhost, :options => {:port=>2375} } }

# Tag an Image.
image.tag('repo' => 'base2', 'force' => true)
# => nil

# Get more information about the Image.
image.json
# => {"id"=>"67859327bf22ef8b5b9b4a6781f72b2015acd894fa03ce07e0db7af170ba468c", "comment"=>"Imported from -", "created"=>"2013-06-19T18:42:58.287944526-04:00", "container_config"=>{"Hostname"=>"", "User"=>"", "Memory"=>0, "MemorySwap"=>0, "CpuShares"=>0, "AttachStdin"=>false, "AttachStdout"=>false, "AttachStderr"=>false, "PortSpecs"=>nil, "Tty"=>false, "OpenStdin"=>false, "StdinOnce"=>false, "Env"=>nil, "Cmd"=>nil, "Dns"=>nil, "Image"=>"", "Volumes"=>nil, "VolumesFrom"=>""}, "docker_version"=>"0.4.0", "architecture"=>"x86_64"}

# View the history of the Image.
image.history
# => [{"Id"=>"67859327bf22", "Created"=>1371681778}]

# Push the Image to the Docker registry. Note that you have to login using
# `Docker.authenticate!` and tag the Image first.
image.push
# => true

# Given a command, create a new Container to run that command in the Image.
image.run('ls -l')
# => Docker::Container { id => aaef712eda, :connection => Docker::Connection { :url => tcp://localhost, :options => {:port=>2375} } }

# Remove the Image from the server.
image.remove(:force => true)
# => true

# Export a single Docker Image to a file
image.save('my_export.tar')
# => Docker::Image { :id => 66b712aef, :connection => Docker::Connection { :url => tcp://localhost, :options => {:port=>2375} } }

# Return the raw image binary data
image.save
# => "abiglongbinarystring"

# Given a Container's export, creates a new Image.
Docker::Image.import('some-export.tar')
# => Docker::Image { :id => 66b712aef, :connection => Docker::Connection { :url => tcp://localhost, :options => {:port=>2375} } }

# `Docker::Image.import` can also import from a URI
Docker::Image.import('http://some-site.net/my-image.tar')
# => Docker::Image { :id => 6b462b2d2, :connection => Docker::Connection { :url => tcp://localhost, :options => {:port=>2375} } }

# For a lower-level interface for importing tars, `Docker::Image.import_stream` may be used.
# It accepts a block, and will call that block until it returns an empty `String`.
File.open('my-export.tar') do |file|
  Docker::Image.import_stream { file.read(1000).to_s }
end

# Create an Image from a Dockerfile as a String.
Docker::Image.build("from base\nrun touch /test")
# => Docker::Image { :id => b750fe79269d2ec9a3c593ef05b4332b1d1a02a62b4accb2c21d589ff2f5f2dc, :connection => Docker::Connection { :url => tcp://localhost, :options => {:port=>2375} } }

# Create an Image from a Dockerfile.
Docker::Image.build_from_dir('.')
# => Docker::Image { :id => 1266dc19e, :connection => Docker::Connection { :url => tcp://localhost, :options => {:port=>2375} } }

# Create an Image from a tar file.
Docker::Image.build_from_tar(File.open('docker_image.tar', 'r'))
# => Docker::Image { :id => 1266dc19e, :connection => Docker::Connection { :url => tcp://localhost, :options => {:port=>2375} } }

# Load all Images on your Docker server.
Docker::Image.all
# => [Docker::Image { :id => b750fe79269d2ec9a3c593ef05b4332b1d1a02a62b4accb2c21d589ff2f5f2dc, :connection => Docker::Connection { :url => tcp://localhost, :options => {:port=>2375} } }, Docker::Image { :id => 8dbd9e392a964056420e5d58ca5cc376ef18e2de93b5cc90e868a1bbc8318c1c, :connection => Docker::Connection { :url => tcp://localhost, :options => {:port=>2375} } }]

# Get Image from the server, with id
Docker::Image.get('df4f1bdecf40')
# => Docker::Image { :id => eb693ec80, :connection => Docker::Connection { :url => tcp://localhost, :options => {:port=>2375} } }

# Check if an image with a given id exists on the server.
Docker::Image.exist?('ef723dcdac09')
# => true

# Export multiple images to a single tarball
names = %w( my_image1 my_image2:not_latest )
Docker::Image.save(names, 'my_export.tar')
# => nil

# Return the raw image binary data
names = %w( my_image1 my_image2:not_latest )
Docker::Image.save(names)
# => "abiglongbinarystring"

# Search the Docker registry.
Docker::Image.search('term' => 'sshd')
# => [Docker::Image { :id => cespare/sshd, :connection => Docker::Connection { :url => tcp://localhost, :options => {:port=>2375} } }, Docker::Image { :id => johnfuller/sshd, :connection => Docker::Connection { :url => tcp://localhost, :options => {:port=>2375} } }, Docker::Image { :id => dhrp/mongodb-sshd, :connection => Docker::Connection { :url => tcp://localhost, :options => {:port=>2375} } }, Docker::Image { :id => rayang2004/sshd, :connection => Docker::Connection { :url => tcp://localhost, :options => {:port=>2375} } }, Docker::Image { :id => dhrp/sshd, :connection => Docker::Connection { :url => tcp://localhost, :options => {:port=>2375} } }, Docker::Image { :id => toorop/daemontools-sshd, :connection => Docker::Connection { :url => tcp://localhost, :options => {:port=>2375} } }, Docker::Image { :id => toorop/daemontools-sshd-nginx, :connection => Docker::Connection { :url => tcp://localhost, :options => {:port=>2375} } }, Docker::Image { :id => toorop/daemontools-sshd-nginx-php-fpm, :connection => Docker::Connection { :url => tcp://localhost, :options => {:port=>2375} } }, Docker::Image { :id => mbkan/lamp, :connection => Docker::Connection { :url => tcp://localhost, :options => {:port=>2375} } }, Docker::Image { :id => toorop/golang, :connection => Docker::Connection { :url => tcp://localhost, :options => {:port=>2375} } }, Docker::Image { :id => wma55/u1210sshd, :connection => Docker::Connection { :url => tcp://localhost, :options => {:port=>2375} } }, Docker::Image { :id => jdswinbank/sshd, :connection => Docker::Connection { :url => tcp://localhost, :options => {:port=>2375} } }, Docker::Image { :id => vgauthier/sshd, :connection => Docker::Connection { :url => tcp://localhost, :options => {:port=>2375} } }]

Containers

Much like the Images, this object also has a one-to-one mapping with the Containers section of the API. Also like Images, .new is a private method, so you must use .create to make an instance.

require 'docker'

# Create a Container.
container = Docker::Container.create('Cmd' => ['ls'], 'Image' => 'base')
# => Docker::Container { :id => 492510dd38e4, :connection => Docker::Connection { :url => tcp://localhost, :options => {:port=>2375} } }

# Get more information about the Container.
container.json
# => {"ID"=>"492510dd38e4da7703f36dfccd013de672b8250f57f59d1555ced647766b5e82", "Created"=>"2013-06-20T10:46:02.897548-04:00", "Path"=>"ls", "Args"=>[], "Config"=>{"Hostname"=>"492510dd38e4", "User"=>"", "Memory"=>0, "MemorySwap"=>0, "CpuShares"=>0, "AttachStdin"=>false, "AttachStdout"=>false, "AttachStderr"=>false, "PortSpecs"=>nil, "Tty"=>false, "OpenStdin"=>false, "StdinOnce"=>false, "Env"=>nil, "Cmd"=>["ls"], "Dns"=>nil, "Image"=>"base", "Volumes"=>nil, "VolumesFrom"=>""}, "State"=>{"Running"=>false, "Pid"=>0, "ExitCode"=>0, "StartedAt"=>"0001-01-01T00:00:00Z", "Ghost"=>false}, "Image"=>"b750fe79269d2ec9a3c593ef05b4332b1d1a02a62b4accb2c21d589ff2f5f2dc", "NetworkSettings"=>{"IpAddress"=>"", "IpPrefixLen"=>0, "Gateway"=>"", "Bridge"=>"", "PortMapping"=>nil}, "SysInitPath"=>"/usr/bin/docker", "ResolvConfPath"=>"/etc/resolv.conf", "Volumes"=>nil}

# Start running the Container.
container.start
# => Docker::Container { :id => 492510dd38e4, :connection => Docker::Connection { :url => tcp://localhost, :options => {:port=>2375} } }

# Stop running the Container.
container.stop
# => Docker::Container { :id => 492510dd38e4, :connection => Docker::Connection { :url => tcp://localhost, :options => {:port=>2375} } }

# Restart the Container.
container.restart
# => Docker::Container { :id => 492510dd38e4, :connection => Docker::Connection { :url => tcp://localhost, :options => {:port=>2375} } }

# Pause the running Container processes.
container.pause
# => Docker::Container { :id => 492510dd38e4, :connection => Docker::Connection { :url => tcp://localhost, :options => {:port=>2375} } }

# Unpause the running Container processes.
container.unpause
# => Docker::Container { :id => 492510dd38e4, :connection => Docker::Connection { :url => tcp://localhost, :options => {:port=>2375} } }

# Kill the command running in the Container.
container.kill
# => Docker::Container { :id => 492510dd38e4, :connection => Docker::Connection { :url => tcp://localhost, :options => {:port=>2375} } }

# Kill the Container specifying the kill signal.
container.kill(:signal => "SIGHUP")
# => Docker::Container { :id => 492510dd38e4, :connection => Docker::Connection { :url => tcp://localhost, :options => {:port=>2375} } }

# Return the currently executing processes in a Container.
container.top
# => [{"PID"=>"4851", "TTY"=>"pts/0", "TIME"=>"00:00:00", "CMD"=>"lxc-start"}]

# Export a Container. Since an export is typically at least 300M, chunks of the
# export are yielded instead of just returning the whole thing.
File.open('export.tar', 'w') do |f|
  container.export { |chunk| file.write(chunk) }
end
# => nil

# Inspect a Container's changes to the file system.
container.changes
# => [{'Path'=>'/dev', 'Kind'=>0}, {'Path'=>'/dev/kmsg', 'Kind'=>1}]

# Copy files/directories from the Container. Note that these are exported as tars.
container.copy('/etc/hosts') { |chunk| puts chunk }

hosts0000644000000000000000000000023412100405636007023 0ustar
127.0.0.1       localhost
::1             localhost ip6-localhost ip6-loopback
fe00::0         ip6-localnet
ff00::0         ip6-mcastprefix
ff02::1         ip6-allnodes
ff02::2         ip6-allrouters
# => Docker::Container { :id => a1759f3e2873, :connection => Docker::Connection { :url => tcp://localhost, :options => {:port=>2375} } }

# Wait for the current command to finish executing. If an argument is given,
# will timeout after that number of seconds. The default is one minute.
container.wait(15)
# => {'StatusCode'=>0}

# Attach to the Container. Currently, the below options are the only valid ones.
# By default, :stream, :stdout, and :stderr are set.
container.attach(:stream => true, :stdin => nil, :stdout => true, :stderr => true, :logs => true, :tty => false)
# => [["bin\nboot\ndev\netc\nhome\nlib\nlib64\nmedia\nmnt\nopt\nproc\nroot\nrun\nsbin\nselinux\nsrv\nsys\ntmp\nusr\nvar", []]

# If you wish to stream the attach method, a block may be supplied.
container = Docker::Container.create('Image' => 'base', 'Cmd' => ['find / -name *'])
container.tap(&:start).attach { |stream, chunk| puts "#{stream}: #{chunk}" }
stderr: 2013/10/30 17:16:24 Unable to locate find / -name *
# => [[], ["2013/10/30 17:16:24 Unable to locate find / -name *\n"]]

# If you want to attach to stdin of the container, supply an IO-like object:
container = Docker::Container.create('Image' => 'base', 'Cmd' => ['cat'], 'OpenStdin' => true, 'StdinOnce' => true)
container.tap(&:start).attach(stdin: StringIO.new("foo\nbar\n"))
# => [["foo\nbar\n"], []]

# Similar to the stdout/stderr attach method, there is logs and streaming_logs

# logs will only return after the container has exited. The output will be the raw output from the logs stream.
# streaming_logs will collect the messages out of the multiplexed form and also execute a block on each line that comes in (block takes a stream and a chunk as arguments)

# Raw logs from a TTY-enabled container after exit
container.logs(stdout: true)
# => "\e]0;root@8866c76564e8: /\aroot@8866c76564e8:/# echo 'i\b \bdocker-api'\r\ndocker-api\r\n\e]0;root@8866c76564e8: /\aroot@8866c76564e8:/# exit\r\n"

# Logs from a non-TTY container with multiplex prefix
container.logs(stdout: true)
# => "\u0001\u0000\u0000\u0000\u0000\u0000\u0000\u00021\n\u0001\u0000\u0000\u0000\u0000\u0000\u0000\u00022\n\u0001\u0000\u0000\u0000\u0000\u0000\u0000\u00023\n\u0001\u0000\u0000\u0000\u0000\u0000\u0000\u00024\n\u0001\u0000\u0000\u0000\u0000\u0000\u0000\u00025\n\u0001\u0000\u0000\u0000\u0000\u0000\u0000\u00026\n\u0001\u0000\u0000\u0000\u0000\u0000\u0000\u00027\n\u0001\u0000\u0000\u0000\u0000\u0000\u0000\u00028\n\u0001\u0000\u0000\u0000\u0000\u0000\u0000\u00029\n\u0001\u0000\u0000\u0000\u0000\u0000\u0000\u000310\n"

# Streaming logs from non-TTY container removing multiplex prefix with a block printing out each line (block not possible with Container#logs)
container.streaming_logs(stdout: true) { |stream, chunk| puts "#{stream}: #{chunk}" }
stdout: 1
stdout: 2
stdout: 3
stdout: 4
stdout: 5
stdout: 6
stdout: 7
stdout: 8
stdout: 9
stdout: 10
# => "1\n\n2\n\n3\n\n4\n\n5\n\n6\n\n7\n\n8\n\n9\n\n10\n"

# If the container has TTY enabled, set `tty => true` to get the raw stream:
command = ["bash", "-c", "if [ -t 1 ]; then echo -n \"I'm a TTY!\"; fi"]
container = Docker::Container.create('Image' => 'ubuntu', 'Cmd' => command, 'Tty' => true)
container.tap(&:start).attach(:tty => true)
# => [["I'm a TTY!"], []]

# Create an Image from a Container's changes.
container.commit
# => Docker::Image { :id => eaeb8d00efdf, :connection => Docker::Connection { :url => tcp://localhost, :options => {:port=>2375} } }

# Commit the Container and run a new command. The second argument is the number
# of seconds the Container should wait before stopping its current command.
container.run('pwd', 10)
# => Docker::Image { :id => 4427be4199ac, :connection => Docker::Connection { :url => tcp://localhost, :options => {:port=>2375} } }

# Run an Exec instance inside the container and capture its output
container.exec('date')
# => [["Wed Nov 26 11:10:30 CST 2014\n"], []]

# Launch an Exec instance without capturing its output
container.exec('./my_service', detach: true)
# => Docker::Exec { :id => be4eaeb8d28a, :connection => Docker::Connection { :url => tcp://localhost, :options => {:port=>2375} } }

# Parse the output of an Exec instance
container.exec('find / -name *') { |stream, chunk| puts "#{stream}: #{chunk}" }
stderr: 2013/10/30 17:16:24 Unable to locate find / -name *
# => [[], ["2013/10/30 17:16:24 Unable to locate find / -name *\n"]]

# Run an Exec instance by grab only the STDOUT output
container.exec('date', stderr: false)
# => [["Wed Nov 26 11:10:30 CST 2014\n"], []]

# Pass input to an Exec instance command via Stdin
container.exec('cat', stdin: StringIO.new("foo\nbar\n"))
# => [["foo\nbar\n"], []]

# Get the raw stream of data from an Exec instance
command = ["bash", "-c", "if [ -t 1 ]; then echo -n \"I'm a TTY!\"; fi"]
container.exec(command, tty: true)
# => [["I'm a TTY!"], []]

# Delete a Container.
container.delete(:force => true)
# => nil

# Request a Container by ID or name.
Docker::Container.get('500f53b25e6e')
# => Docker::Container { :id => , :connection => Docker::Connection { :url => tcp://localhost, :options => {:port=>2375} } }

# Request all of the Containers. By default, will only return the running Containers.
Docker::Container.all(:all => true)
# => [Docker::Container { :id => , :connection => Docker::Connection { :url => tcp://localhost, :options => {:port=>2375} } }]

Events

require 'docker'

# Action on a stream of events as they come in
Docker::Event.stream { |event| puts event; break }
Docker::Event { :status => create, :id => aeb8b55726df63bdd69d41e1b2650131d7ce32ca0d2fa5cbc75f24d0df34c7b0, :from => base:latest, :time => 1416958554 }
# => nil

# Action on all events after a given time (will execute the block for all events up till the current time, and wait to execute on any new events after)
Docker::Event.since(1416958763) { |event| puts event; puts Time.now.to_i; break }
Docker::Event { :status => die, :id => 663005cdeb56f50177c395a817dbc8bdcfbdfbdaef329043b409ecb97fb68d7e, :from => base:latest, :time => 1416958764 }
1416959041
# => nil

These methods are prone to read timeouts. Docker.options[:read_timeout] will need to be made higher than 60 seconds if expecting a long time between events.

Connecting to Multiple Servers

By default, each object connects to the connection specified by Docker.connection. If you need to connect to multiple servers, you can do so by specifying the connection on #new or in the utilizing class method. For example:

require 'docker'

Docker::Container.all({}, Docker::Connection.new('tcp://example.com:2375', {}))

Rake Task

To create images through rake, a DSL task is provided. For example:

require 'rake'
require 'docker'

image 'repo:tag' do
  image = Docker::Image.create('fromImage' => 'repo', 'tag' => 'old_tag')
  image = Docker::Image.run('rm -rf /etc').commit
  image.tag('repo' => 'repo', 'tag' => 'tag')
end

image 'repo:new_tag' => 'repo:tag' do
  image = Docker::Image.create('fromImage' => 'repo', 'tag' => 'tag')
  image = image.insert_local('localPath' => 'some-file.tar.gz', 'outputPath' => '/')
  image.tag('repo' => 'repo', 'tag' => 'new_tag')
end

Not supported (yet)

License

This program is licensed under the MIT license. See LICENSE for details.