providers/docker: can specify links

plugins/providers/docker/action/create.rb

@@ -29,6 +29,9 @@ module VagrantPlugins
             params[:ports].each do |pair|
               env[:ui].detail("  Port: #{pair}")
             end
+            params[:links].each do |name, other|
+              env[:ui].detail("  Link: #{name}:#{other}")
+            end
 
             cid = @driver.create(params)
           end
@@ -44,12 +47,19 @@ module VagrantPlugins
           container_name.gsub!(/[^-a-z0-9_]/i, "")
           container_name << "_#{Time.now.to_i}"
 
+          links = {}
+          @provider_config._links.each do |link|
+            parts = link.split(":", 2)
+            links[parts[0]] = parts[1]
+          end
+
           {
             cmd:        @provider_config.cmd,
             env:        @provider_config.env,
             extra_args: @provider_config.create_args,
             hostname:   @machine_config.vm.hostname,
             image:      @provider_config.image,
+            links:      links,
             name:       container_name,
             ports:      forwarded_ports,
             privileged: @provider_config.privileged,

plugins/providers/docker/config.rb

@@ -53,6 +53,7 @@ module VagrantPlugins
         @env        = {}
         @has_ssh    = UNSET_VALUE
         @image      = UNSET_VALUE
+        @links      = []
         @ports      = []
         @privileged = UNSET_VALUE
         @remains_running = UNSET_VALUE
@@ -61,12 +62,20 @@ module VagrantPlugins
         @vagrant_vagrantfile = UNSET_VALUE
       end
 
+      def link(name)
+        @links << name
+      end
+
       def merge(other)
         super.tap do |result|
           env = {}
           env.merge!(@env) if @env
           env.merge!(other.env) if other.env
           result.env = env
+
+          links = _links.dup
+          links += other._links
+          result.instance_variable_set(:@links, links)
         end
       end
 
@@ -85,11 +94,27 @@ module VagrantPlugins
       def validate(machine)
         errors = _detected_errors
 
+        @links.each do |link|
+          parts = link.split(":")
+          if parts.length != 2 || parts[0] == "" || parts[1] == ""
+            errors << I18n.t(
+              "docker_provider.errors.config.invalid_link", link: link)
+          end
+        end
+
         # TODO: Detect if base image has a CMD / ENTRYPOINT set before erroring out
         errors << I18n.t("docker_provider.errors.config.cmd_not_set") if @cmd == UNSET_VALUE
 
         { "docker provider" => errors }
       end
+
+      #--------------------------------------------------------------
+      # Functions below should not be called by config files
+      #--------------------------------------------------------------
+
+      def _links
+        @links
+      end
     end
   end
 end

plugins/providers/docker/driver.rb

@@ -16,6 +16,7 @@ module VagrantPlugins
 
       def create(params)
         image   = params.fetch(:image)
+        links   = params.fetch(:links)
         ports   = Array(params[:ports])
         volumes = Array(params[:volumes])
         name    = params.fetch(:name)
@@ -24,6 +25,7 @@ module VagrantPlugins
 
         run_cmd = %W(docker run --name #{name} -d)
         run_cmd += env.map { |k,v| ['-e', "#{k}=#{v}"] }
+        run_cmd += links.map { |k, v| ['--link', "#{k}:#{v}"] }
         run_cmd += ports.map { |p| ['-p', p.to_s] }
         run_cmd += volumes.map { |v| ['-v', v.to_s] }
         run_cmd += %W(--privileged) if params[:privileged]

templates/locales/providers_docker.yml

@@ -86,8 +86,8 @@ en:
         and notify them to not use this communicator for anything except the
         "docker" provider.
       config:
-        cmd_not_set: |-
-          The Docker command has not been set!
+        invalid_link: |-
+          Invalid link (should be 'name:alias'): "%{link}"
       docker_provider_nfs_without_privileged: |-
         You've configured a NFS synced folder but didn't enable privileged
         mode for the container. Please set the `privileged` option to true

test/unit/plugins/providers/docker/config_spec.rb

@@ -42,13 +42,34 @@ describe VagrantPlugins::DockerProvider::Config do
     assert_valid
   end
 
+  describe "#link" do
+    it "should be valid with good links" do
+      subject.link "foo:bar"
+      subject.link "db:blah"
+      subject.finalize!
+      assert_valid
+    end
+
+    it "should be invalid if not name:alias" do
+      subject.link "foo"
+      subject.finalize!
+      assert_invalid
+    end
+
+    it "should be invalid if too many colons" do
+      subject.link "foo:bar:baz"
+      subject.finalize!
+      assert_invalid
+    end
+  end
+
   describe "#merge" do
+    let(:one) { described_class.new }
+    let(:two) { described_class.new }
+
+    subject { one.merge(two) }
+
     context "env vars" do
-      let(:one) { described_class.new }
-      let(:two) { described_class.new }
-
-      subject { one.merge(two) }
-
       it "should merge the values" do
         one.env["foo"] = "bar"
         two.env["bar"] = "baz"
@@ -59,5 +80,15 @@ describe VagrantPlugins::DockerProvider::Config do
         })
       end
     end
+
+    context "links" do
+      it "should merge the links" do
+        one.link "foo"
+        two.link "bar"
+
+        expect(subject._links).to eq([
+          "foo", "bar"])
+      end
+    end
   end
 end