Prototype ps command. Closes #20

Gemfile

@@ -5,4 +5,5 @@ gemspec
 
 group :development do
   gem 'pry'
+  gem 'pry-byebug'
 end

README.md

@@ -44,6 +44,12 @@ compose = Docker::Compose.new
 compose.version
 
 compose.up(detached:true)
+
+exited = compose.ps.where { |c| !c.up? }
+puts "We have some exited containers: " + exited.join(', ')
+
+sum = compose.ps.inject(0) { |a,c| a + c.size }
+puts format("Composition is using %.1f MiB disk space", sum/1024/1024) 
 ```
 
 ### Invoking from Rake

bin/console

@@ -3,12 +3,15 @@
 require "bundler/setup"
 require "docker/compose"
 
-# You can add fixtures and/or initialization code here to make experimenting
-# with your gem easier. You can also use a different console, if you like.
+@session = Docker::Compose::Session.new
 
-# (If you use this, don't forget to add pry to your Gemfile!)
-# require "pry"
-# Pry.start
-
-require "irb"
-IRB.start
+begin
+  require 'pry'
+  Pry.start(@session)
+rescue LoadError
+  require 'irb'
+  IRB.setup nil
+  IRB.conf[:MAIN_CONTEXT] = IRB::Irb.new.context
+  require 'irb/ext/multi-irb'
+  IRB.irb nil, @session
+end

docker-compose.yml

@@ -0,0 +1,6 @@
+apple:
+  image: busybox
+  command: /bin/sh -c 'sleep 3600'
+orange:
+  image: busybox
+  command: /bin/sh -c 'sleep 3600'

lib/docker/compose.rb

@@ -1,5 +1,9 @@
+require 'net/http'
+
 require_relative 'compose/version'
 require_relative 'compose/error'
+require_relative 'compose/container'
+require_relative 'compose/collection'
 require_relative 'compose/session'
 require_relative 'compose/net_info'
 require_relative 'compose/mapper'

lib/docker/compose/collection.rb

@@ -0,0 +1,13 @@
+module Docker::Compose
+  class Collection < Array
+    # @example find containers that are up
+    #   who_is_up = coll.where { |c| c.up? }
+    # @example count space taken by all containers
+    #   coll.map { |c| c.size }.inject(0) { |a, x| a + x }
+    def where
+      hits = Collection.new
+      self.each { |c| hits << c if yield(c) }
+      hits
+    end
+  end
+end

lib/docker/compose/container.rb

@@ -0,0 +1,63 @@
+module Docker::Compose
+  class Container
+    PS_STATUS = /^([A-Za-z]+) ?\(?([0-9]*)\)? ?(.*)$/i
+
+    attr_reader :id, :image, :size, :status, :exitstatus
+    attr_reader :names, :labels, :ports, :mounts
+
+    # @param [String] id
+    # @param [String] image
+    # @param [String,Numeric] size
+    # @param [String,#map] status e.g. ['Exited', '0', '3 minutes ago']
+    # @param [String,#map] names
+    # @param [String,#map] labels
+    # @param [String,#map] ports
+    # @param [String,#map] mounts
+    def initialize(id, image, size, status, names, labels, ports, mounts)
+      if size.is_a?(String)
+        scalar, units = size.split(' ')
+        scalar = size[0].to_i # lazy: invalid --> 0
+        mult = case units.downcase
+        when 'b'  then 1
+        when 'kb' then 1_024
+        when 'mb' then 1_024^2
+        when 'gb' then 1_024^3
+        when 'tb' then 1_024^4
+        else
+          raise Error.new('Service#new', units, 'Impossibly large unit')
+        end
+        size = scalar * mult
+      end
+
+      if status.is_a?(String)
+        status = PS_STATUS.match(status)
+        raise Error.new('Service#new', status, 'Unrecognized status') unless status
+      end
+
+      names = names.split(',') if names.is_a?(String)
+      labels = labels.split(',') if labels.is_a?(String)
+      ports = ports.split(',') if ports.is_a?(String)
+      mounts = ports.split(',') if mounts.is_a?(String)
+
+      @id = id
+      @image = image
+      @size = size
+      @status = status[1].downcase.to_sym
+      @exitstatus = !status[2].empty? && status[2].to_i # sloppy!
+      @names = names
+      @labels = labels
+      @ports = ports
+      @mounts = mounts
+    end
+
+    # @return [String]
+    def name
+      names.first
+    end
+
+    # @return [Boolean]
+    def up?
+      self.status == :up
+    end
+  end
+end

lib/docker/compose/error.rb

@@ -8,8 +8,17 @@ class Error < RuntimeError
     def initialize(cmd, status, detail)
       @status = status
       @detail = detail
+
       brief = detail.split("\n").first || '(no output)'
-      message = format("'%s' failed with status %d: %s", cmd, status, brief)
+
+      case status
+      when Numeric
+        status = status.to_s
+      else
+        status = "'#{status}'"
+      end
+
+      message = format("'%s' failed with status %s: %s", cmd, status, brief)
       super(message)
     end
   end

lib/docker/compose/session.rb

@@ -40,6 +40,17 @@ def logs(*services)
       true
     end
 
+    def ps()
+      lines = run!('ps', q:true).split(/[\r\n]+/)
+      containers = Collection.new
+
+      lines.each do |id|
+        containers << docker_ps(id)
+      end
+
+      containers
+    end
+
     # Idempotently up the given services in the project.
     # @param [Array] services list of String service names to run
     # @param [Boolean] detached if true, to start services in the background;
@@ -63,7 +74,7 @@ def rm(*services, force:false, volumes:false, all:true)
       run!('rm', {f:force, v:volumes, a:all}, services)
     end
 
-    # Idempotently run a service in the project.
+    # Idempotently run an arbitrary command with a service container.
     # @param [String] service name to run
     # @param [String] cmd command statement to run
     # @param [Boolean] detached if true, to start services in the background;
@@ -138,5 +149,51 @@ def run!(*args)
         out
       end
     end
+
+    private
+
+    PS_FORMAT = '({{.ID}}) ({{.Image}}) ({{.Size}}) ({{.Status}}) ({{.Names}}) ({{.Labels}}) ({{.Ports}}) ({{.Mounts}})'
+    PS_REGEXP = /\(([^)])\) \(([^)])\) \(([^)])\) \(([^)])\) \(([^)])\) \(([^)])\) \(([^)])\) \(([^)])\)/
+
+    def docker_ps(id)
+      # docker ps -f id=c9e116fe1ce9732f7f715386078a317d8e322adaf98fa41507d1077d3af9ba02
+      cmd = @shell.run('docker', 'ps', a:true, f:"id=#{id}", format:PS_FORMAT).join
+      status, out, err = cmd.status, cmd.captured_output, cmd.captured_error
+      raise Error, "Unexpected output from docker ps" unless status == 0
+      lines = out.split(/[\r\n]+/)
+      return nil if lines.empty?
+      l = lines.shift
+      m = parse(l)
+      raise Error, "Cannot parse docker ps output: #{l}" unless m.respond_to?(:size) && m.size == 6
+      return Container.new(m[0],m[1],m[2],m[3],m[4],m[5],m[6],m[7])
+    end
+
+    def parse(str)
+      fields = []
+      nest = 0
+      field = ''
+      str.each_char do |ch|
+        if nest == 0
+          nest += 1 if ch == '('
+        else
+          if ch == '('
+            nest += 1
+          elsif ch == ')'
+            nest -= 1
+            field << ch unless nest == 0
+          else
+            field << ch
+          end
+        end
+
+        # nest just became 0
+        if nest == 0 && !field.empty?
+          fields << field
+          field = ''
+        end
+      end
+
+      fields
+    end
   end
 end

spec/docker/compose/session_spec.rb

@@ -24,6 +24,12 @@
     end
   end
 
+  describe '#ps' do
+    it 'lists containers' do
+      session.ps
+    end
+  end
+
   describe '#up' do
     it 'runs containers' do
       expect(shell).to receive(:run).with('docker-compose', anything, 'up', anything, anything)

spec/spec_helper.rb

@@ -1,2 +1,8 @@
 $LOAD_PATH.unshift File.expand_path('../../lib', __FILE__)
 require 'docker/compose'
+
+begin
+  require 'pry'
+rescue LoadError
+  # bah!
+end