ec2_api_req_sign.erl

%% process for signing ec2 api requests:
%% http://docs.amazonwebservices.com/AWSEC2/latest/DeveloperGuide/index.html?using-query-api.html
s_query(PLparams) ->
    {ok,SaccKeyId} = application:get_env(monitor,amazon_access_key_id),
    {{Iyr,Imth,Iday},{Ihr,Imin,Isec}} = erlang:universaltime(),
    Sdatetime0 = io_lib:format("~4.10.0B-~2.10.0B-~2.10.0BT~2.10.0B:~2.10.0B:~2.10.0BZ",
                               [Iyr,Imth,Iday,Ihr,Imin,Isec]),
    Sdatetime1 = lists:flatten(Sdatetime0),
    PL0 = [{"SignatureMethod","HmacSHA1"},
           {"SignatureVersion","2"},
           {"AWSAccessKeyId",SaccKeyId},
           {"Version","2009-11-30"},
           {"Timestamp",Sdatetime1}
           | PLparams],
    PL1 = lists:keysort(1, PL0),
    PL2 = [{url_encode(Skey),
            url_encode(Sval)}
           || {Skey,Sval} <- PL1],
    Sparams = string:join([Skey++"="++Sval
               || {Skey,Sval} <- PL2], "&"),
    Ssignature0 = lists:flatten(io_lib:format("GET~nec2.amazonaws.com~n/~n~s", [Sparams])),
    {ok,SaccKey} = application:get_env(monitor,amazon_secret_access_key),
    Ssignature1 = binary_to_list(crypto:sha_mac(SaccKey,Ssignature0)),
    Ssignature2 = ibrowse_lib:encode_base64(Ssignature1),
    Ssignature3 = url_encode(Ssignature2),
    "http://ec2.amazonaws.com/?" ++ Sparams ++ "&Signature=" ++ Ssignature3.