Including a build number in Clojure using boot

clojure-build-number.clj

;; core.clj

(defn version []
  (or (some-> "version.txt" clojure.java.io/resource slurp clojure.string/trim)
      "unknown"))

;; build.boot

(defn get-version []
  (or (System/getenv "CIRCLE_SHA1") "SNAPSHOT"))

(deftask add-version-txt
  "Add a file called version.txt to the fileset, for inclusion in the jar"
  []
  (with-pre-wrap fs
    (let [t (tmp-dir!)]
      (spit (clojure.java.io/file t "version.txt") (get-version))
      (-> fs (add-resource t) commit!))))

(deftask dist ;; this is just an example - adapt your `dist` task
  (comp 
        (pom :project 'example
             :version (get-version))
        (add-version-txt)
        (uber)
        (aot :namespace '#{example.core})
        (jar :main 'example.core,
             :file "example.jar")
        (target :dir #{"target"})))