Add the ability to read SNS credentials from the default credential chain

src/riemann/sns.clj

@@ -4,7 +4,8 @@
   (your-publisher \"your::arn\"). Or simply call sns-publish or
   sns-publish-async directly."
   (:import (com.amazonaws AmazonWebServiceClient)
-           [com.amazonaws.auth BasicAWSCredentials]
+           (com.amazonaws.auth BasicAWSCredentials
+                               DefaultAWSCredentialsProviderChain)
            [com.amazonaws.regions RegionUtils]
            [com.amazonaws.handlers AsyncHandler]
            (com.amazonaws.services.sns AmazonSNS
@@ -45,9 +46,12 @@
   (RegionUtils/getRegion name))
 
 (defn- aws-credentials [credentials]
-  (BasicAWSCredentials.
-   (:access-key credentials)
-   (:secret-key credentials)))
+  (if (or (nil? (:access-key credentials))
+          (nil? (:secret-key credentials)))
+    (DefaultAWSCredentialsProviderChain.)
+    (BasicAWSCredentials.
+     (:access-key credentials)
+     (:secret-key credentials))))
 
 (defn- aws-client
   [klass opts]
@@ -101,7 +105,7 @@
     (doseq [arn arns]
        (publish arn))))
 
-(def aws-credential-keys #{:access-key :secret-key :region}) 
+(def aws-credential-keys #{:access-key :secret-key :region})
 (def aws-async-keys #{:async :success :error})
 (def aws-keys (union aws-credential-keys aws-async-keys))
 
@@ -156,19 +160,19 @@
                            :secret-key \"your-secret-key\"
                            :subject \"something went wrong\"
                            :async true}))
-  
+
   By default, riemann uses (riemann.common/subject events) and
   (riemann.common/body events) to format messages.
   You can set your own subject or body formatter functions by including
   :subject or :body in msg-opts. These formatting functions take a sequence of
   events and return a string.
 
-  (def sns (sns-publisher {} {:body (fn [events] 
+  (def sns (sns-publisher {} {:body (fn [events]
                                       (apply prn-str events))}))"
   ([] (sns-publisher {}))
   ([opts]
      (let [{aws-opts   :aws-opts
-            async-opts :async-opts 
+            async-opts :async-opts
             msg-opts   :msg-opts} (sift-opts opts)]
        (sns-publisher aws-opts msg-opts async-opts)))
   ([aws-opts msg-opts & [async-opts]]

test/riemann/sns_test.clj

@@ -24,10 +24,10 @@
 (deftest override-formatting-test
   (let [message (#'riemann.sns/compose-message
                  {:body (fn [events]
-                          (apply str "body " 
+                          (apply str "body "
                                  (map :service events)))
-                  :subject (fn [events] 
-                             (apply str "subject " 
+                  :subject (fn [events]
+                             (apply str "subject "
                                     (map :service events)))
                   :arn ["my:arn"]}
                  {:service "foo"})]
@@ -59,6 +59,14 @@
       (stream fake-event))
     (is (= @a ["test:arn" fake-event-body fake-event-subject]))))
 
+(deftest sns-publisher-default-chain-test
+  (let [a (promise)
+        sns (sns-publisher)
+        stream (sns "test:arn")]
+    (with-redefs [riemann.sns/aws-sns-publish #(deliver a [%2 %3 %4])]
+      (stream fake-event))
+    (is (= @a ["test:arn" fake-event-body fake-event-subject]))))
+
 (deftest sns-publisher-async-test
   (let [a (promise)
         done (promise)
@@ -100,12 +108,14 @@
         done (promise)
         fail (promise)
         sns-sync (sns-publisher aws-opts)
+        sns-default-chain (sns-publisher {})
         sns-async (sns-publisher aws-opts {} {:async true})
         sns-callbacks (sns-publisher aws-opts {} {:async true
                                                   :success #(deliver done [%2])
                                                   :error #(deliver fail [%1])})
         event (merge fake-event {:time (unix-time)})]
     ((sns-sync env-arn) (merge event {:service "sns sync test"}))
+    ((sns-default-chain env-arn) (merge event {:service "sns default credential chain test"}))
     ((sns-async env-arn) (merge event {:service "sns async test"}))
     ((sns-callbacks env-arn) (merge event {:service "sns async callback test"}))
     ((sns-callbacks (str env-arn ":non:existent")) (merge event {:service "sns async callback test"}))