Add secrets to :context map

README.adoc

@@ -19,7 +19,7 @@ Why Babashka for OpenFaaS instead of Clojure proper?:
 ** that Function cold start times are kept to a minimum.
 ** a rapid development feedback loop.
 ** a simple REPL workflow - just start everything all over again, it's fast.
-* Babashka is designed for minimal memory usage, allowing you to scale up your single-purpose functions with comparable RAM consumption.
+* Babashka is designed for minimal memory usage, allowing you to scale up your single-purpose Functions with comparable RAM consumption.
 
 == Prerequisites
 
@@ -103,6 +103,31 @@ my-function:
   :my-env2 2}
 ----
 
+If you declare secrets in the `stack.yml` file, these will be available in `:context` map as well. Let's start with an example:
+[source, yml]
+----
+my-function:
+  lang: bb
+  handler: ./anything/my-function
+  image: ${DOCKER_REGISTRY_IMG_ORG_PATH}/my-function
+  secrets:
+    - foo
+    - baz
+----
+A secret value that is an EDN string, when internally parsed as a Clojure map, will have its content spliced into the `:context` map. Otherwise, the secret will be available in the `:context` map as `{:secret-name <secret-value>}`, with `<secret-value>` parsed as a Clojure data structure other than a map.
+
+Following up from the definition of `my-function` above, we define the following secrets:
+[source, bash]
+----
+echo 'bar' | faas-cli secret create foo
+echo '{:spam "eggs"}' | faas-cli secret create baz
+----
+becomes this in the `:context` map:
+[source, clojure]
+----
+{:foo "bar" :spam "eggs"}
+----
+
 In `bb-streaming` language:
 [source, clojure]
 ----
@@ -113,7 +138,9 @@ The `event` is extracted from the HTTP payload body, and the function return is
 
 === Function tests
 
-To test the code of a Function, a `test` directory in the Function's top-level directory is provided, containing:
+Tests for your Function run when you build the Function image (`faas-cli build`).
+
+A `test` directory in the Function's top-level directory is provided, containing:
 
 * `run_tests.clj`, with the namespace that will be used to run the tests. You can use any test library and test runner you like.
 * a `bb.edn` file where test dependencies can be added. Remove this file if you don't need to add any dependencies.

template/bb/index.clj

@@ -9,9 +9,27 @@
     [ring.middleware.text :refer [wrap-text-body]]
     [ring.middleware.headers :refer [wrap-lowercase-headers wrap-friendly-headers]]
     [ring.util.walk :as ring-walk]
+    [ring.util.string :as ring-string]
     [compojure.response :as response]
+    [babashka.fs :as fs]
+    [clojure.edn :as edn]
     [handler :as function]))
 
+(defn ->secret [filepath secret-raw]
+  (let [secret (edn/read-string secret-raw)]
+    (if (map? secret)
+      secret
+      (let [secret-key (-> filepath fs/file-name keyword)]
+        {secret-key (ring-string/read-string secret-raw)}))))
+
+(defn ->secrets []
+  (when (fs/exists? "/var/openfaas/secrets")
+    (->> (fs/list-dir "/var/openfaas/secrets")
+      (map #(let [filepath (-> % str)
+                  secret-raw (slurp filepath)]
+             (->secret filepath secret-raw)))
+      (apply merge))))
+
 (def keywords? #(if (nil? %) true %))
 
 (def fn-arg-cnt #(some-> % meta :arglists first count))
@@ -36,7 +54,8 @@
 
 (defn -main []
   (let [env (ring-walk/format-context (System/getenv))
+        context (merge env (->secrets))
         faas-fn (wrap-arg #'function/handler)]
-    (run-server (->app faas-fn env)
+    (run-server (->app faas-fn context)
                 {:port 8082})
     @(promise)))

template/bb/tests.clj

@@ -33,6 +33,11 @@
   "asd" => "asd"
   :qwer => "qwer")
 
+(eg index/->secret
+  [_ "{:foo \"bar\"}"] => {:foo "bar"}
+  ["foo" "bar"]           => {:foo "bar"}
+  ["foo" "[1 \"baz\"]"]   => {:foo [1 "baz"]})
+
 (eg index/keywords?
   true  => true
   false => false