diff --git a/.travis.yml b/.travis.yml
index 132cdf7..b2f3aed 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -1,9 +1,6 @@
-install:
-   - make rebar3
-script: 
-   - make && make test
+script: make && make test
 language: erlang
 otp_release:
-   - 18.2.1
-   - 17.5
+   - 19.2
+   - 18.3
 
diff --git a/Makefile b/Makefile
index 7645a11..1ef1996 100644
--- a/Makefile
+++ b/Makefile
@@ -4,7 +4,7 @@
 ## @description
 ##   Makefile to build and release Erlang applications using standard development tools
 ##
-## @version 0.11.5
+## @version 0.11.8
 
 #####################################################################
 ##
@@ -22,9 +22,12 @@ TEST   ?= ${APP}
 S3     ?=
 VMI    ?= fogfish/erlang
 NET    ?= lo0
-URL 	 ?= undefined
+URL    ?= undefined
 LATEST ?= latest
 
+## rebar version (no spaces at end)
+REBAR  ?= 3.3.2
+
 ## root path to benchmark framework
 BB     = ../basho_bench
 SSHENV = /tmp/ssh-agent.conf
@@ -46,17 +49,17 @@ EFLAGS = \
 ## self-extracting bundle wrapper
 BUNDLE_INIT = PREFIX=${PREFIX}\nREL=${PREFIX}/${REL}\nAPP=${APP}\nVSN=${VSN}\nLINE=`grep -a -n "BUNDLE:$$" $$0`\nmkdir -p $${REL}\ntail -n +$$(( $${LINE%%%%:*} + 1)) $$0 | gzip -vdc - | tar -C $${REL} -xvf - > /dev/null\n
 BUNDLE_FREE = exit\nBUNDLE:\n
-BUILDER = FROM ${VMI}\nRUN mkdir ${APP}\nCOPY . ${APP}/\nRUN cd ${APP} && make && make rel\n
+BUILDER = FROM ${VMI}\nARG VERSION=\nRUN mkdir ${APP}\nCOPY . ${APP}/\nRUN cd ${APP} && make VSN=\x24{VERSION} && make rel VSN=\x24{VERSION}\n
 CTRUN   = \
-	-module(test). \
-	-export([run/1]). \
-	run(Spec) -> \
-   	{ok, Test} = file:consult(Spec), \
-   	case lists:keyfind(node, 1, Test) of \
-      	false -> ct:run_test([{spec, Spec}]); \
+   -module(test). \
+   -export([run/1]). \
+   run(Spec) -> \
+      {ok, Test} = file:consult(Spec), \
+      Error = case lists:keyfind(node, 1, Test) of \
+         false -> element(2, ct:run_test([{spec, Spec}])); \
          true  -> ct_master:run(Spec) \
-   	end, \
-		erlang:halt().
+      end, \
+      erlang:halt(Error).
 
 #####################################################################
 ##
@@ -119,7 +122,7 @@ relx.config: rel/relx.config.src
 	@cat $< | sed 's/release/release, {${APP}, "${VSN}"}/' > $@ 
 else
 ${PKG}.tar.gz: _build/dockermake
-	@docker build --file=$< --force-rm=true	--tag=build/${APP}:latest . ;\
+	@docker build --file=$< --force-rm=true --build-arg="VERSION=${VSN}" --tag=build/${APP}:latest . ;\
 	I=`docker create build/${APP}:latest` ;\
 	docker cp $$I:/${APP}/$@ $@ ;\
 	docker rm -f $$I ;\
@@ -136,7 +139,7 @@ docker: rel/Dockerfile
 		--build-arg APP=${APP} \
 		--build-arg VSN=${VSN} \
 		-t ${URL}/${APP}:${VSN} -f $< .
-	docker tag -f ${URL}/${APP}:${VSN} ${URL}/${APP}:${LATEST}
+	docker tag ${URL}/${APP}:${VSN} ${URL}/${APP}:${LATEST}
 
 
 
@@ -207,8 +210,9 @@ console: ${PKG}.tar.gz
 ##
 #####################################################################
 rebar3:
-	@curl -L -O https://s3.amazonaws.com/rebar3/rebar3 ; \
-	chmod ugo+x $@
+	@echo "==> install rebar (${REBAR})" ;\
+	curl -L -O --progress-bar https://github.com/erlang/rebar3/releases/download/${REBAR}/rebar3 ;\
+	chmod +x $@
 
 .PHONY: test rel deps all pkg 
 
diff --git a/src/cache.app.src b/src/cache.app.src
index 45f2782..03ba8a2 100644
--- a/src/cache.app.src
+++ b/src/cache.app.src
@@ -1,7 +1,7 @@
 {application, cache,
    [
       {description, "in-memory cache"},
-      {vsn,         "2.1.1"},
+      {vsn,         "2.2.0"},
       {modules,     []},
       {registered,  []},
       {applications,[
diff --git a/src/cache.erl b/src/cache.erl
index 14b75c6..ff06ac0 100644
--- a/src/cache.erl
+++ b/src/cache.erl
@@ -62,7 +62,11 @@
    remove/2,  
    remove/3, 
    remove_/2,
-   remove_/3
+   remove_/3,
+   apply/3,
+   apply/4,
+   apply_/4,
+   apply_/3
 ]).
 %% extended cache i/o interface
 -export([
@@ -303,6 +307,36 @@ remove_(Cache, Key, true) ->
 remove_(Cache, Key, false) ->
    send(Cache, {remove, Key}).
 
+%%
+%% synchronous apply function to entity on cache
+%% the function maps element, the new value is returned
+%% the operation prolongs value ttl
+-spec apply(cache(), key(), fun((_) -> _)) -> val() | undefined.
+-spec apply(cache(), key(), fun((_) -> _), timeout()) -> val() | undefined.
+
+apply(Cache, Key, Fun) ->
+   cache:apply(Cache, Key, Fun, ?CONFIG_TIMEOUT).
+
+apply(Cache, Key, Fun, Timeout) ->
+   call(Cache, {apply, Key, Fun}, Timeout).
+
+
+%%
+%% asynchronous apply function to entity on cache
+%% the function maps element, the new value is returned
+%% the operation prolongs value ttl
+-spec apply_(cache(), key(), fun((_) -> _)) -> ok | reference().
+-spec apply_(cache(), key(), fun((_) -> _), true | false) -> ok | reference().
+
+apply_(Cache, Key, Fun) ->
+   cache:apply_(Cache, Key, Fun, false).
+
+apply_(Cache, Key, Fun, true) ->
+   cast(Cache, {apply, Key, Fun});
+
+apply_(Cache, Key, Fun, false) ->
+   cast(Cache, {apply, Key, Fun}).
+
 %%%----------------------------------------------------------------------------   
 %%%
 %%% extended cache i/o interface
diff --git a/src/cache_bucket.erl b/src/cache_bucket.erl
index a8d9425..9210bc8 100644
--- a/src/cache_bucket.erl
+++ b/src/cache_bucket.erl
@@ -121,6 +121,10 @@ handle_call({ttl, Key}, _, State) ->
 handle_call({remove, Key}, _, State) ->
    {reply, ok, cache_remove(Key, State)};
 
+handle_call({apply, Key, Fun}, _, State0) ->
+   {Result, State1} = cache_apply(Key, Fun, State0),
+   {reply, Result, State1};
+
 handle_call({acc, Key, Val}, _, State0) ->
    {Result, State1} = cache_acc(Key, Val, State0),
    {reply, Result, State1};
@@ -328,6 +332,16 @@ cache_remove(Key, #cache{name=_Name, heap=Heap}=State) ->
    ?DEBUG("cache ~p: remove ~p~n", [_Name, Key]),
    State.
 
+%%
+%%
+cache_apply(Key, Fun, State) ->
+   case Fun(cache_get(Key, State)) of
+      undefined  ->
+         {undefined, State};
+      Val ->
+         {Val, cache_put(Key, Val, undefined, State)}
+   end.   
+
 %%
 %% @todo: reduce one write
 cache_acc(Key, Val, State)
diff --git a/test/cache_SUITE.erl b/test/cache_SUITE.erl
index eb85c14..c6e3e86 100644
--- a/test/cache_SUITE.erl
+++ b/test/cache_SUITE.erl
@@ -42,7 +42,9 @@
    lookup/1,
    has/1,
    remove/1,
-   remove_/1
+   remove_/1,
+   apply/1,
+   apply_/1
 ]).
 
 %%
@@ -77,7 +79,7 @@ groups() ->
       {primitives, [parallel], 
          [lifecycle]},
       {basic_io, [parallel], 
-         [put, put_, get, lookup, has, remove, remove_]},
+         [put, put_, get, lookup, has, remove, remove_, apply, apply_]},
       {extended_io, [parallel], 
          [acc, set, add, replace, append, append_, prepend, prepend_, delete]}
    ].
@@ -169,6 +171,22 @@ remove_(_Config) ->
    false= cache:has(Cache, key),
    ok = cache:drop(Cache).
 
+apply(_Config) ->
+   {ok, Cache} = cache:start_link([]),
+   val = cache:apply(Cache, key, fun(undefined) -> val end),
+   val = cache:get(Cache, key),
+   lav = cache:apply(Cache, key, fun(val) -> lav end),
+   lav = cache:get(Cache, key),
+   ok = cache:drop(Cache).   
+
+apply_(_Config) ->
+   {ok, Cache} = cache:start_link([]),
+   cache:apply_(Cache, key, fun(undefined) -> val end),
+   val = cache:get(Cache, key),
+   cache:apply_(Cache, key, fun(val) -> lav end),
+   lav = cache:get(Cache, key),
+   ok = cache:drop(Cache).   
+
 %%%----------------------------------------------------------------------------   
 %%%
 %%% cache extended i/o