GitHub - rthomas/clj-etcd: etcd client library for Clojure. (original) (raw)

clj-etcd

A client library for the https://github.com/coreos/etcd project.

Usage

Usage of the library is simple and it returns a map of data the same as the json returned by etcd.

In your project

Leiningen

[clj-etcd "0.1.3"]

From the REPL

Require the library

user=> (require '[clj-etcd.core :as etcd])
nil

Define an instance to connect to, here we will just use a local instance of etcd.

user=> (def base-url "http://localhost:4001")
#'user/base-url

Setting the value of a key

All functions in clj-etcd require the base-url as the first parameter.

user=> (etcd/set! base-url "my/key" "my-value")
{:action "set", 
         :key "/my/key", 
         :value "my-value", 
         :modifiedIndex 271}

clj-etcd also supports all of the set options as optional keys - valid options are :ttl, :prev-val, :prev-index and :prev-exist.

user=> (etcd/set! base-url "my/key" "my-value" :ttl 100)
{:action "set", 
         :key "/my/key", 
         :prevValue "my-value", 
         :value "my-value", 
         :expiration "2013-11-27T16:43:06.005677156+11:00", 
         :ttl 100, 
         :modifiedIndex 272}

user=> (etcd/set! base-url "my/key" "my-new-value" :prev-val "my-value")
{:action "compareAndSwap", 
         :key "/my/key", 
         :prevValue "my-value", 
         :value "my-new-value", 
         :modifiedIndex 273}

Getting the value of a key or directory

We use the ls function to list the value of a key.

  user=> (etcd/ls base-url "my/key")
  {:action "get", 
           :key "/my/key", 
           :value "my-new-value", 
           :modifiedIndex 275}

This also works on directories.

 user=> (etcd/ls base-url "my")
 {:action "get", 
          :key "/my", 
          :dir true, 
          :kvs [{:key "/my/key", :value "my-new-value", :modifiedIndex 275}
                {:key "/my/deep", :dir true, :modifiedIndex 274}], 
          :modifiedIndex 271}

Checking if a key exists or if it is a directory

We can test the existence of a key and whether this key is a directory.

user=> (etcd/set! base-url "my/deep/key" :bam)
{:action "set", 
         :key "/my/deep/key", 
         :value ":bam", 
         :modifiedIndex 274}
user=> (etcd/exists? base-url "my/deep/key")
true
user=> (etcd/exists? base-url "my/deeper/key")
false
user=> (etcd/dir? base-url "my/deep/key")
false
user=> (etcd/dir? base-url "my/deep")
true

Waiting on a change for a key

We can also wait on a change for a key, this also support the :recursive optional parameter. The future will have the map data when it is dereferenced (when an update is made to that key).

user=> (etcd/wait base-url "some/key")
#<core$future_call$reify__6267@43e3cae: :pending>

Building from source

Building

This is a simple leiningen project, a lein compile should do or a lein install to get it into your local repo.

Testing

A lein test will run the unit tests.

License

Copyright © 2013 Ryan Thomas

Distributed under the Eclipse Public License either version 1.0 or (at your option) any later version.