Allow customizing audit broadcast with env

When invoking the audit broadcast command, provide a few environment
variables so that people can customize the format of the message if they
want.

We currently provide `MRSK_PERFORMER`, `MRSK_ROLE`, `MRSK_DESTINATION` and
`MRSK_EVENT`.

Also adds the destination to the default message, which we continue to
send as the first argument as before.

README.md

@@ -677,6 +677,15 @@ That'll post a line like follows to a preconfigured chatbot in Basecamp:
 [My App] [dhh] Rolled back to version d264c4e92470ad1bd18590f04466787262f605de
 ```
 
+In addition to the formatted message, MRSK sets a number of environment variables with the components of the broadcast.
+You can use these (rather than the command argument) if you want more control over how the message is formatted.
+MRSK currently sets:
+
+- `MRSK_PERFORMER` - the user performing the command
+- `MRSK_DESTINATION` - the destination
+- `MRSK_ROLE` - the specific role being targetted, if any
+- `MRSK_EVENT` - text of the action (e.g. "Deployed app@150b24f")
+
 ### Custom healthcheck
 
 MRSK defaults to checking the health of your application again `/up` on port 3000 up to 7 times. You can tailor the behaviour with the `healthcheck` setting:

lib/mrsk/cli/base.rb

@@ -73,7 +73,9 @@ module Mrsk::Cli
       end
 
       def audit_broadcast(line)
-        run_locally { execute *MRSK.auditor.broadcast(line), verbosity: :debug }
+        if broadcast = MRSK.auditor.broadcast(line)
+          system(MRSK.auditor.broadcast_environment(line), broadcast)
+        end
       end
 
       def with_lock

lib/mrsk/commands/auditor.rb

@@ -22,6 +22,15 @@ class Mrsk::Commands::Auditor < Mrsk::Commands::Base
     end
   end
 
+  def broadcast_environment(line)
+    {
+      "MRSK_PERFORMER" => performer,
+      "MRSK_ROLE" => role,
+      "MRSK_DESTINATION" => config.destination,
+      "MRSK_EVENT" => line
+    }
+  end
+
   def reveal
     [ :tail, "-n", 50, audit_log_file ]
   end
@@ -36,7 +45,7 @@ class Mrsk::Commands::Auditor < Mrsk::Commands::Base
     end
 
     def tagged_broadcast_line(line)
-      tagged_line performer_tag, role_tag, line
+      tagged_line performer_tag, role_tag, destination_tag, line
     end
 
     def tagged_line(*tags_and_line)
@@ -47,11 +56,19 @@ class Mrsk::Commands::Auditor < Mrsk::Commands::Base
       "[#{Time.now.to_fs(:db)}]"
     end
 
+    def performer
+      `whoami`.strip
+    end
+
     def performer_tag
-      "[#{`whoami`.strip}]"
+      "[#{performer}]"
     end
 
     def role_tag
       "[#{role}]" if role
     end
+
+    def destination_tag
+      "[#{config.destination}]" if config.destination
+    end
 end

test/commands/auditor_test.rb

@@ -31,9 +31,26 @@ class CommandsAuditorTest < ActiveSupport::TestCase
   end
 
   test "broadcast" do
-    assert_match \
+    Mrsk::Commands::Auditor.any_instance.stubs(:performer).returns("bob")
-      /bin\/audit_broadcast '\[.*\] app removed container'/,
+    @role = "web"
-      new_command.broadcast("app removed container").join(" ")
+    @destination = "staging"
+
+    assert_equal \
+      ["bin/audit_broadcast", "'[bob] [web] [staging] app removed container'"],
+      new_command.broadcast("app removed container")
+  end
+
+  test "broadcast environment" do
+    Mrsk::Commands::Auditor.any_instance.stubs(:performer).returns("bob")
+    @role = "web"
+    @destination = "staging"
+
+    env = new_command.broadcast_environment("app removed container")
+
+    assert_equal "bob", env["MRSK_PERFORMER"]
+    assert_equal "web", env["MRSK_ROLE"]
+    assert_equal "staging", env["MRSK_DESTINATION"]
+    assert_equal "app removed container", env["MRSK_EVENT"]
   end
 
   private