Fix snappyer as optional dependency

Author: belltoy

README.md

@@ -25,7 +25,7 @@ Why "brod"? [http://en.wikipedia.org/wiki/Max_Brod](http://en.wikipedia.org/wiki
 - Pick latest supported version when sending requests to kafka.
 - Direct APIs for message send/fetch and cluster inspection/management without having to start clients/producers/consumers.
 - A escriptized command-line tool for message send/fetch and cluster inspection/management.
-- Configurable compression library. `snappy` compression is supported by default.
+- Configurable compression library. No compression is supported by default for both producers and consumers.
   For more compression options, see [kafka_protocol/README](https://github.com/kafka4beam/kafka_protocol/blob/master/README.md#compression-support)
 
 ## Building and testing
@@ -114,6 +114,20 @@ two-level supervision trees.
 To use producers or consumers, you have to start at least one cient that
 will manage them.
 
+### Compression
+
+Brod does not dependent on any compression/decompression implementation by default.
+To enable them, you must add the compression application as dependency.
+
+For example:
+
+```erlang
+% rebar.config
+{deps, [
+    {snappyer, "1.2.8"}
+].
+```
+
 ### Start clients by default
 
 You may include client configs in `sys.config` have them started by default

rebar.config

@@ -1,6 +1,5 @@
 {deps, [ {supervisor3, "1.1.11"}
        , {kafka_protocol, "4.1.2"}
-       , {snappyer, "1.2.8"}
        ]}.
 {project_plugins, [{rebar3_lint, "~> 1.0.2"}]}.
 {edoc_opts, [{preprocess, true}, {macros, [{build_brod_cli, true}]}]}.
@@ -12,6 +11,7 @@
   {brod_cli, [
     {deps, [ {docopt, {git, "https://github.com/zmstone/docopt-erl.git", {branch, "0.1.3"}}}
            , {jsone, "1.7.0"}
+           , {snappyer, "1.2.8"}
     ]},
     {erl_opts, [warnings_as_errors, {d, build_brod_cli}]},
     {escript_name, brod_cli},
@@ -30,6 +30,7 @@
            , {meck, "0.9.2"}
            , {proper, "1.4.0"}
            , {snabbkaffe, "1.0.1"}
+           , {snappyer, "1.2.8"}
     ]},
     {erl_opts, [warnings_as_errors, {d, build_brod_cli}]}
   ]}

rebar.lock

@@ -1,17 +1,14 @@
 {"1.2.0",
 [{<<"crc32cer">>,{pkg,<<"crc32cer">>,<<"0.1.8">>},1},
  {<<"kafka_protocol">>,{pkg,<<"kafka_protocol">>,<<"4.1.2">>},0},
- {<<"snappyer">>,{pkg,<<"snappyer">>,<<"1.2.8">>},0},
  {<<"supervisor3">>,{pkg,<<"supervisor3">>,<<"1.1.11">>},0}]}.
 [
 {pkg_hash,[
  {<<"crc32cer">>, <<"C6C2275C5FB60A95F4935D414F30B50EE9CFED494081C9B36EBB02EDFC2F48DB">>},
  {<<"kafka_protocol">>, <<"EE45DB88BD83526B1D3079DE19D5331AD7D755E549C00EC6F2CAA47C591E9588">>},
- {<<"snappyer">>, <<"201CE9067A33C71A6A5087C0C3A49A010B17112D461E6DF696C722DCB6D0934A">>},
  {<<"supervisor3">>, <<"D81CDEC31D102FDE407423E1D05B569572850DEEBED86B951D5233C387CBA80B">>}]},
 {pkg_hash_ext,[
  {<<"crc32cer">>, <<"251499085482920DEB6C9B7AADABF9FB4C432F96ADD97AB42AEE4501E5B6F591">>},
  {<<"kafka_protocol">>, <<"04AD1A8CD2A57479907AA049489149FEBCCDDAD247338718A1A77E64F50E4B07">>},
- {<<"snappyer">>, <<"35518E79A28548B56D8FD6AEE2F565F12F51C2D3D053F9CFA817C83BE88C4F3D">>},
  {<<"supervisor3">>, <<"E6C2DEDBCABCBA24995A218ACA12DB5E208B80D3252692B22EF0F1A266104B50">>}]}
 ].

src/brod.app.src

@@ -3,7 +3,7 @@
  [{description,"Apache Kafka Erlang client library"},
   {vsn,"git"},
   {registered,[]},
-  {applications,[kernel,stdlib,kafka_protocol,supervisor3,snappyer]},
+  {applications,[kernel,stdlib,kafka_protocol,supervisor3]},
   {env,[]},
   {mod, {brod, []}},
   {modules,[]},