Documentation update

guides/configuration.md

@@ -1,7 +1,7 @@
 ## Configuration
 
 Amoc is configured through environment variables (uppercase with prefix ``AMOC_``).
-Note that the environment variables are evaluated as Erlang code.
+Note that by default, environment variables values are deserialized as Erlang terms. This behavior can be customized by providing an alternative parsing module in the `config_parser_mod` configuration parameter for the amoc application. It can be done using the [application:set_env/4](https://www.erlang.org/doc/man/application#set_env-4) interface or via a [config file](https://www.erlang.org/doc/man/config). The custom parsing module must implement the `amoc_config_env` behavior.
 
 Amoc supports the following generic configuration parameters:
 
@@ -12,7 +12,7 @@ Amoc supports the following generic configuration parameters:
 * ``api_port`` - a port for the amoc REST interfaces:
     * default value - 4000
     * example: `AMOC_API_PORT="4000"`
-                                      
+
 * ``interarrival`` - a delay (in ms, for each node in the cluster independently) between creating the processes
   for two consecutive users:
     * default value - 50 ms.
@@ -61,7 +61,7 @@ where
 * **Default:** this field is mandatory
 
 ### `description`
-* **Syntax:** A string describing how this variable is used, can be extracted by APIs to document the behaviour
+* **Syntax:** A string describing how this variable is used, can be extracted by APIs to document the behavior
 * **Example:** `description = "a description of this variable"`
 * **Default:** this field is mandatory
 
@@ -91,17 +91,17 @@ An action to take when the value of this variable is updated. It is triggered at
 - If it is set to `none`, all updates are allowed.
 - If it is an `mfa`, the given function will be called on the old and new value.
 
-## Reasonale
+## Rationale
 
-The reason why the `-required_variable(...)` is preferred over the usual behaviour
+The reason why the `-required_variable(...)` is preferred over the usual behavior
 callback is because the orchestration tools can easily extract the attributes even
 without the compilation, while configuring via a callback, requires a successful
 compilation of the module. As an example, a module:
 ```erlang
 -module(example).
 -include("some_unavailable_header.hrl").
 -some_attr({"some", value}).
--some_attr([{another, "value"}, 
+-some_attr([{another, "value"},
             {yet, <<"another">>, "value"}]).
 ```
 cannot be compiled without the ``some_unavailable_header.hrl`` file, but we still
@@ -115,9 +115,9 @@ error
 {ok,[{attribute,1,file,{"example.erl",1}},
      {attribute,1,module,example},
      {error,{2,epp,{include,file,"some_unavailable_header.hrl"}}},
-     {attribute,3,some_attr,{"some",value}}, 
+     {attribute,3,some_attr,{"some",value}},
      {attribute,4,some_attr,
-                [{another,"value"},{yet,<<"another">>,"value"}]}, 
+                [{another,"value"},{yet,<<"another">>,"value"}]},
      {eof,6}]}
 3> lists:flatten([Value || {attribute, _, some_attr, Value} <- AbstractForm]).
 [{"some",value},

src/amoc_config/amoc_config_env.erl

@@ -12,7 +12,7 @@
 %% @end
 -module(amoc_config_env).
 
--export([get/1, get/2]).
+-export([get/2]).
 
 -define(DEFAULT_PARSER_MODULE, amoc_config_parser).
 
@@ -21,19 +21,8 @@
 %% ------------------------------------------------------------------
 %% API
 %% ------------------------------------------------------------------
--spec get(amoc_config:name()) -> amoc_config:value().
-get(Name) ->
-    get(Name, undefined).
-
 -spec get(amoc_config:name(), amoc_config:value()) -> amoc_config:value().
 get(Name, Default) when is_atom(Name) ->
-    get_os_env(Name, Default).
-
-%% ------------------------------------------------------------------
-%% Internal Function Definitions
-%% ------------------------------------------------------------------
--spec get_os_env(amoc_config:name(), amoc_config:value()) -> amoc_config:value().
-get_os_env(Name, Default) ->
     EnvName = os_env_name(Name),
     Value = os:getenv(EnvName),
     case parse_value(Value, Default) of
@@ -47,6 +36,9 @@ get_os_env(Name, Default) ->
             Default
     end.
 
+%% ------------------------------------------------------------------
+%% Internal Function Definitions
+%% ------------------------------------------------------------------
 -spec os_env_name(amoc_config:name()) -> string().
 os_env_name(Name) when is_atom(Name) ->
     "AMOC_" ++ string:uppercase(erlang:atom_to_list(Name)).
@@ -55,8 +47,7 @@ os_env_name(Name) when is_atom(Name) ->
 parse_value(false, Default) -> {ok, Default};
 parse_value("", Default)    -> {ok, Default};
 parse_value(String, _) ->
-    App = application:get_application(?MODULE),
-    Mod = application:get_env(App, config_parser_mod, ?DEFAULT_PARSER_MODULE),
+    Mod = application:get_env(amoc, config_parser_mod, ?DEFAULT_PARSER_MODULE),
     try Mod:parse_value(String) of
         {ok, Value} -> {ok, Value};
         {error, Error} -> {error, Error};

src/amoc_config/amoc_config_utils.erl

@@ -11,8 +11,7 @@
          merge_config/2,
          override_config/2,
          store_scenario_config/1,
-         create_amoc_config_ets/0,
-         find_all_vars/1]).
+         create_amoc_config_ets/0]).
 
 -spec maybe_error(error_type(), [{error, reason()} | {ok, any()}]) ->
     error() | {ok, [any()]}.
@@ -71,9 +70,3 @@ create_amoc_config_ets() ->
                                         protected,
                                         {keypos, #module_parameter.name},
                                         {read_concurrency, true}]).
-
--spec find_all_vars(atom()) -> [any()].
-find_all_vars(Name) ->
-    AllValues = [application:get_env(App, Name)
-                 || {App, _, _} <- application:loaded_applications()],
-    [Value || {ok, Value} <- AllValues].

test/amoc_config_env_SUITE.erl

@@ -35,27 +35,22 @@ end_per_suite(_) ->
 
 init_per_testcase(valid_custom_parser_test, Config) ->
     meck:new(?MOCK_MOD, [non_strict, no_link]),
-    App = application:get_application(amoc_config_env),
-    application:set_env(App, config_parser_mod, ?MOCK_MOD),
-    ct:pal("amoc_config_env module belongs to '~p' application", [App]),
+    set_config_parser_module(?MOCK_MOD),
     ct:pal("AMOC_* OS env. variables:~n   ~p",
            [[AmocEnv || "AMOC_" ++ _ = AmocEnv <- os:getenv()]]),
     Config;
 init_per_testcase(invalid_custom_parser_test, Config) ->
-    App = application:get_application(amoc_config_env),
     %% setting non-existing config parser module
-    application:set_env(App, config_parser_mod, invalid_parser_module),
+    set_config_parser_module(invalid_parser_module),
     Config;
 init_per_testcase(_, Config) ->
     Config.
 
 end_per_testcase(valid_custom_parser_test, _Config) ->
-    App = application:get_application(amoc_config_env),
-    application:unset_env(App, config_parser_mod),
+    unset_config_parser_module(),
     meck:unload();
 end_per_testcase(invalid_custom_parser_test, _Config) ->
-    App = application:get_application(amoc_config_env),
-    application:unset_env(App, config_parser_mod);
+    unset_config_parser_module();
 end_per_testcase(_, _Config) ->
     ok.
 %%-----------------------------------------------------------------------------------
@@ -130,3 +125,13 @@ invalid_custom_parser_test(_) ->
     ?assertEqual(default_value, get_env(unset_var, default_value)),
     ?assertEqual(undefined, get_env(empty_var)),
     ?assertEqual(default_value, get_env(empty_var, default_value)).
+
+%%-----------------------------------------------------------------------------------
+%% helper functions
+%%-----------------------------------------------------------------------------------
+
+set_config_parser_module(Mod) ->
+    application:set_env(amoc, config_parser_mod, Mod).
+
+unset_config_parser_module() ->
+    application:unset_env(amoc, config_parser_mod).

test/amoc_config_helper.erl

@@ -15,7 +15,7 @@ env_name(Name) ->
     "AMOC_" ++ string:uppercase(erlang:atom_to_list(Name)).
 
 get_env(Name) ->
-    amoc_config_env:get(Name).
+    get_env(Name, undefined).
 
 get_env(Name, Default) ->
     amoc_config_env:get(Name, Default).