Riak local client is what you want to read from or write to Riak while running riak attach, and Erlang MapReduce job, or a post_commit hook.
11: {ok,Client} = riak:local_client()
-> {ok,{riak_client,['dev1@127.0.0.1',undefined]}}
12: riak_client:list_buckets(Client)
-> {ok,[<<"test5">>,<<"testr52">>,<<"test2">>,<<"test1">>]}
13: riak_object:new(<<"groceries">>, <<"mine">>, <<"eggs & bacon">>)
-> {r_object,<<"groceries">>,<<"mine">>,
[{r_content,{dict,0,16,16,8,80,48,
{[],[],[],[],[],[],[],[],[],[],[],[],[],[],...},
{{[],[],[],[],[],[],[],[],[],[],[],[],...}}},
<<"eggs & bacon">>}],
[],
{dict,1,16,16,8,80,48,
{[],[],[],[],[],[],[],[],[],[],[],[],[],[],[],...},
{{[],[],[],[],[],[],[],[],[],[],[],[],[],...}}},
undefined}
24: riak_client:put(O, Client)
-> ok
28: riak_client:get(<<"groceries">>, <<"mine">>, Client)
-> {ok,{r_object,<<"groceries">>,<<"mine">>,
[{r_content,{dict,3,16,16,8,80,48,
{[],[],[],[],[],[],[],[],[],[],[],[],...},
{{[],[],[],[],[],[],[],[],[],[],...}}},
<<"eggs & bacon">>}],
[{<<157,62,8,202,83,177,50,174>>,{1,63571692235}}],
{dict,1,16,16,8,80,48,
{[],[],[],[],[],[],[],[],[],[],[],[],[],...},
{{[],[],[],[],[],[],[],[],[],[],[],...}}},
undefined}}