add plugin to detect user sessions using loginctl

lib/ohai/plugins/linux/sessions.rb

@@ -0,0 +1,54 @@
+#
+# Author:: Davide Cavalca <[email protected]>
+# Copyright:: Copyright (c) 2016 Facebook
+# License:: Apache License, Version 2.0
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+#
+
+require "ohai/util/file_helper"
+
+include Ohai::Util::FileHelper
+
+Ohai.plugin(:Sessions) do
+  provides "sessions/by_session", "sessions/by_user"
+
+  collect_data(:linux) do
+    loginctl_path = which("loginctl")
+    if loginctl_path
+      cmd = "#{loginctl_path} --no-pager --no-legend --no-ask-password " +
+        "list-sessions"
+      loginctl = shell_out(cmd)
+
+      sessions Mash.new unless sessions
+      sessions[:by_session] = Mash.new unless sessions[:by_session]
+      sessions[:by_user] = Mash.new unless sessions[:by_user]
+
+      loginctl.stdout.split("\n").each do |line|
+        session, uid, user, seat = line.split
+        s = {
+          "session" => session,
+          "uid" => uid,
+          "user" => user,
+          "seat" => seat,
+        }
+        sessions[:by_session][session] = s
+        if sessions[:by_user][user]
+          sessions[:by_user][user] << s
+        else
+          sessions[:by_user][user] = [s]
+        end
+      end
+    end
+  end
+end

spec/unit/plugins/linux/sessions_spec.rb

@@ -0,0 +1,98 @@
+#
+# Author:: Davide Cavalca <[email protected]>
+# Copyright:: Copyright (c) 2016 Facebook
+# License:: Apache License, Version 2.0
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+#
+
+require File.expand_path(File.dirname(__FILE__) + "/../../../spec_helper.rb")
+
+describe Ohai::System, "Linux sessions plugin" do
+  let(:plugin) { get_plugin("linux/sessions") }
+
+  before(:each) do
+    allow(plugin).to receive(:collect_os).and_return(:linux)
+  end
+
+  it "should populate sessions if loginctl is found" do
+    loginctl_out = <<-LOGINCTL_OUT
+        c1        118 Debian-gdm       seat0
+       318          0 root
+        46          0 root
+       306       1000 joe
+LOGINCTL_OUT
+    allow(plugin).to receive(:which).with("loginctl").and_return("/bin/loginctl")
+    allow(plugin).to receive(:shell_out).with("/bin/loginctl --no-pager --no-legend --no-ask-password list-sessions").and_return(mock_shell_out(0, loginctl_out, ""))
+    plugin.run
+    expect(plugin[:sessions].to_hash).to eq({
+      "by_session" => {
+        "c1" => {
+          "session" => "c1",
+          "uid" => "118",
+          "user" => "Debian-gdm",
+          "seat" => "seat0",
+        },
+        "318" => {
+          "session" => "318",
+          "uid" => "0",
+          "user" => "root",
+          "seat" => nil,
+        },
+        "46" => {
+          "session" => "46",
+          "uid" => "0",
+          "user" => "root",
+          "seat" => nil,
+        },
+        "306" => {
+          "session" => "306",
+          "uid" => "1000",
+          "user" => "joe",
+          "seat" => nil,
+        }
+      },
+      "by_user" => {
+        "Debian-gdm" => [{
+          "session" => "c1",
+          "uid" => "118",
+          "user" => "Debian-gdm",
+          "seat" => "seat0",
+        }],
+        "root" => [{
+          "session" => "318",
+          "uid" => "0",
+          "user" => "root",
+          "seat" => nil
+        }, {
+          "session" => "46",
+          "uid" => "0",
+          "user" => "root",
+          "seat" => nil,
+        }],
+        "joe" => [{
+          "session" => "306",
+          "uid" => "1000",
+          "user" => "joe",
+          "seat" => nil,
+        }],
+      },
+    })
+  end
+
+  it "should not populate sessions if loginctl is not found" do
+    allow(plugin).to receive(:which).with("loginctl").and_return(false)
+    plugin.run
+    expect(plugin[:sessions]).to be(nil)
+  end
+end