Merge branch 'doobinay-utc-time'

README.md

@@ -237,6 +237,22 @@ Examples:
 [{server,{pid, ["(", pid, ")"], ["(Unknown Server)"]}}] -> user provided server metadata, otherwise "(<?.?.?>)", otherwise "(Unknown Server)"
 ```
 
+Universal time
+--------------
+By default, lager formats timestamps as local time for whatever computer
+generated the log message.
+
+To make lager use UTC timestamps, you can set the `sasl` application's
+`utc_log` configuration parameter to `true` in your application configuration
+file.
+
+Example:
+
+```
+%% format log timestamps as UTC
+[{sasl, [{utc_log, true}]}].
+```
+
 Error logger integration
 ------------------------
 Lager is also supplied with a `error_logger` handler module that translates

test/lager_test_backend.erl

@@ -696,6 +696,26 @@ lager_test_() ->
                         ?assertError(badarg, lager:md("zookeeper zephyr")),
                         ok
                 end
+            },
+            {"dates should be local by default",
+                fun() ->
+                        lager:warning("so long, and thanks for all the fish"),
+                        ?assertEqual(1, count()),
+                        {_Level, {_Date, Time}, _Message, _Metadata}  = pop(),
+                        ?assertEqual(nomatch, binary:match(iolist_to_binary(Time), <<"UTC">>)),
+                        ok
+                end
+            },
+            {"dates should be UTC if SASL is configured as UTC",
+                fun() ->
+                        application:set_env(sasl, utc_log, true),
+                        lager:warning("so long, and thanks for all the fish"),
+                        application:set_env(sasl, utc_log, false),
+                        ?assertEqual(1, count()),
+                        {_Level, {_Date, Time}, _Message, _Metadata}  = pop(),
+                        ?assertNotEqual(nomatch, binary:match(iolist_to_binary(Time), <<"UTC">>)),
+                        ok
+                end
             }
         ]
     }.