Generate a config file for testing

Prior to this change, the template file etc/emqx.conf is used
directly in testing, as a result, mustache style directories
are created e.g. `{{ platform_log_dir }}` which should have been
replaced with a config varialbe e.g. `log`

In this change, Makefile targets are added as `ct` dependency
to download bbmustach, load the template input, replace with
variableds defined in 'vars' file, finally to etc/gen.emqx.conf.
The direct usage of etc/emqx.conf in test code are replaced with
gen.emqx.conf

.gitignore

@@ -32,3 +32,5 @@ rebar3.crashdump
 .DS_Store
 rebar.config
 emqx.iml
+bbmustache/
+etc/gen.emqx.conf

Makefile

@@ -51,6 +51,29 @@ DIALYZER_OPTS := --verbose --statistics -Werror_handling -Wrace_conditions #-Wun
 
 include erlang.mk
 
-app.config::
-	./deps/cuttlefish/cuttlefish -l info -e etc/ -c etc/emqx.conf -i priv/emqx.schema -d data/
+clean:: gen-clean
+
+.PHONY: gen-clean
+gen-clean:
+	@rm -rf bbmustache
+	@rm -f etc/gen.emqx.conf
+
+bbmustache:
+	$(verbose) git clone https://github.com/soranoba/bbmustache.git && pushd bbmustache && ./rebar3 compile && popd
+
+# This hack is to generate a conf file for testing
+# relx overlay is used for release
+etc/gen.emqx.conf: bbmustache etc/emqx.conf
+	$(verbose) erl -noshell -pa bbmustache/_build/default/lib/bbmustache/ebin -eval \
+		"{ok, Temp} = file:read_file('etc/emqx.conf'), \
+		{ok, Vars0} = file:consult('vars'), \
+		Vars = [{atom_to_list(N), list_to_binary(V)} || {N, V} <- Vars0], \
+		Targ = bbmustache:render(Temp, Vars), \
+		ok = file:write_file('etc/gen.emqx.conf', Targ), \
+		halt(0)."
+
+app.config: etc/gen.emqx.conf
+	$(verbose) ./deps/cuttlefish/cuttlefish -l info -e etc/ -c etc/gen.emqx.conf -i priv/emqx.schema -d data/
+
+ct: app.config
 

test/emqx_ct_broker_helpers.erl

@@ -63,7 +63,7 @@ run_teardown_steps() ->
 
 generate_config() ->
     Schema = cuttlefish_schema:files([local_path(["priv", "emqx.schema"])]),
-    Conf = conf_parse:file([local_path(["etc", "emqx.conf"])]),
+    Conf = conf_parse:file([local_path(["etc", "gen.emqx.conf"])]),
     cuttlefish_generator:map(Schema, Conf).
 
 get_base_dir(Module) ->

test/emqx_listeners_SUITE.erl

@@ -49,7 +49,7 @@ restart_listeners(_) ->
     
 generate_config() ->
     Schema = cuttlefish_schema:files([local_path(["priv", "emqx.schema"])]),
-    Conf = conf_parse:file([local_path(["etc", "emqx.conf"])]),
+    Conf = conf_parse:file([local_path(["etc", "gen.emqx.conf"])]),
     cuttlefish_generator:map(Schema, Conf).
 
 set_app_env({App, Lists}) ->

vars

@@ -0,0 +1,9 @@
+%% vars here are for test only, not intended for release
+
+{platform_bin_dir,  "bin"}.
+{platform_data_dir, "data"}.
+{platform_etc_dir,  "etc"}.
+{platform_lib_dir,  "lib"}.
+{platform_log_dir,  "log"}.
+{platform_plugins_dir,  "plugins"}.
+