Service discovery method

project.clj

@@ -6,4 +6,5 @@
   :dependencies [[org.clojure/clojure "1.5.1"]
                  [http-kit "2.1.16"]
                  [org.clojure/data.json "0.2.4"]
+                 ; [com.brweber2/clj-dns "0.0.2"] ; Doesn't seem to support custom resolvers easily
                  ])

src/consult/httpkitdnssr.clj

@@ -0,0 +1,62 @@
+(ns consult.httpkitdnssr
+  "
+  A small wrapper around HTTP-Kit (http://http-kit.org/) constructed
+  to use DNS SR on localhost as provided by Consul (http://www.consul.io/docs/agent/http.html).
+
+  This should enable http-kit to talk to consul-cluster services by name.
+  "
+  (:require  [org.httpkit.client :as    http]
+             [clojure.java.shell :refer [sh]]
+             [clojure.data.json  :as    json]))
+
+(defn words [text] (clojure.string/split text #"\s"))
+
+(defn fields [item] (clojure.string/split item #"\t"))
+
+(defn clean-header [string] (clojure.string/replace string #";; |:" ""))
+
+(defn parse-lines [[header & items]]
+  (if (empty? items)
+    {}
+    (let [ initial (take-while #(re-find #"^[a-z]" %) items)
+           final   (drop-while #(re-find #"^[a-z]" %) items)
+          ]
+      (merge {(clean-header header) (map fields initial)} (parse-lines final)))))
+
+(defn dig [service]
+  (let [ response (sh "dig" "@127.0.0.1" "-p" "8600" (str service ".service.consul") "SRV")
+         output   (:out response)
+         lines    (clojure.string/split output #"\n")
+         clean    (filter #(re-find #"^;; ADDITION|^;; ANSWER|^[a-z]" %) lines)
+         groups   (parse-lines clean)
+        ] groups))
+
+(defn find-name [answer] (last answer))
+
+(defn find-port [answer] (let [field  (nth (last answer) 4)
+                               tokens (words field)
+                               item   (nth tokens 2)
+                               ] item))
+
+(defn find-ip   [service-name additional]
+  ;(filter #(= service-name (first %)) additional)
+  (map last additional) ; TODO
+  )
+
+(defn query [service]
+  (let [service-info (dig service)
+        answer       (service-info "ANSWER SECTION")
+        service-name (find-name answer)
+        _            (or service-name (throw (ex-info "Could not find service name" {:service service})))
+        service-port (find-port answer)
+        additional   (service-info "ADDITIONAL SECTION")
+        service-ips  (find-ip service-name additional)]
+        _            (or service-ips (throw (ex-info "Could not find service IP" {:service service})))
+    (map #(str "" % ":" service-port) service-ips)))
+
+(defn service-get-index [service]
+  (let [ url      (str "http://" (first (query service)) "/index.html")
+         response (http/get url) ]
+    @response))
+
+(service-get-index "foobar")