erl-etcd

Erlang driver for etcd. Requried R16 or higher, basing on etcd v2 http APIs.

supporting feature

• basic etcd api (etcd module)
• watch a dir and cache all changed value in this dir into ets (etcd_ets_cache module)
• get and set json value into etcd keys (etcd_json_kv module)

Quick start

Config etcd address and enable this mode:

{etcd, [
    {addr, ["http://address1:port1", "http://address2:port2", "http://address3:port3"]}
    {enable, true}
    ]

if set to disable, you will get nothing

Start the application and do some basic action:

%% start the application
application:start(etcd).

%% set a key
etcd:set("/message", "hello").

%% get a key/dir
{ok, Body} = etcd:get("/message").

%% delete a key/dir
etcd:delete("/message").

%% watch a key
Callback = fun(V) -> io:format(V), ok end,
etcd:watch("/message", Callback).

%% watch a dir
Callback = fun(V) -> io:format(V), ok end,
etcd:watch_dir("/test_dir", Callback).

Refer to src/etcd.erl to see more details about APIs.

using json kv feature

consider the following json object:

{
"key":"value",
"obj": {"obj_key":"obj_value"},
"list": [1,2,3, {"obj_list":"list_value"}]
}

make this a string into erlang , and call the following api:

etcd_json_kv:set_from_string("/json_test_prefix", JsonString).

And then you can get json value in etcd:

/json_test_prefix/key -> "value"
/json_test_prefix/obj/obj_key -> "obj_value"
/json_test_prefix/list/0 -> "1"
/json_test_prefix/list/1 -> "2"
/json_test_prefix/list/2 -> "3"
/json_test_prefix/list/4/obj_list -> "list_value"

So you can get them as native etcd get request.

To get the json string back , you can call the following API:

etcd_json_kv:get_as_string("/json_test_prefix")

Refer to src/etcd_json_kv.erl for more details.

using ets as cache and watch for change

Try this:

etcd_ets_cache:watch_prefix(
        "/test_dir",
        fun(Key, OldValue, NewValue) ->
        		io:format("~p", [{Key, OldValue, NewValue}]),
        		ok
        end).

This will watch on the prefix of /test_dir, any changed on this dir will be caught and [Key, OldValue, NewValue] will be passed to the callback. And the newest value is stored into ets, and you can access them by calling

etcd_ets_cache:get("/test_dir/keyx").

refer to src/etcd_ets_cache.erl for more details

v0.2.1

• add list_dir command

v0.2.0

• add json_kv
• integer ets cache with etcd watch
• bug fix for space and plus url encoding

v0.1-beta

• All wait behaviour will be monitored by etcd_sup
• Add almost all opt support

v0.1-alpha

This is the first alpha version of etcd erlang client. Supporting:

• Basic CURD
• Basic wait operation