Clojure lein uberjar: java.lang.ClassNotFoundException

Question

I have a Clojure library that has two gen-class directives. When I run lein run , there are no issues. However, when I run lein uberjar , I get errors:

$ lein uberjar
Compiling 6 source files to /Users/frank/src/user/target/uberjar/classes
Compiling user.common
Compiling user.core
java.lang.ClassNotFoundException: user.server.UserAuthenticationServer, compiling:(user/core.clj:15:30)
Exception in thread "main" java.lang.ClassNotFoundException: user.server.UserAuthenticationServer, compiling:(user/core.clj:15:30)
  at clojure.lang.Compiler.analyzeSeq(Compiler.java:6926)
.....
  at clojure.lang.Compiler.analyze(Compiler.java:6701)
Caused by: java.lang.ClassNotFoundException: user.server.UserAuthenticationServer
  at java.net.URLClassLoader.findClass(URLClassLoader.java:381)
...
  at clojure.lang.Compiler.analyzeSeq(Compiler.java:6919)
  ... 86 more

In addition to the generated java files, there is the project.clj , server.clj , and core.clj .

project.clj

(defproject user "0.1.0-SNAPSHOT"
  :dependencies [[org.clojure/clojure                        "1.9.0-alpha14"]
                 [io.grpc/grpc-core                          "1.7.0"]
                 [io.grpc/grpc-netty                         "1.7.0"
                  :exclusions [io.grpc/grpc-core]]
                 [io.grpc/grpc-protobuf                      "1.7.0"]
                 [io.grpc/grpc-stub                          "1.7.0"]]
  :main ^:skip-aot user.core
  :aot [user.server]
  :target-path "target/%s"
  :source-paths ["src/clj"]
  :java-source-paths ["src/generated/proto"
                      "src/generated/grpc"]
  :profiles {:uberjar {:aot :all}})

core.clj

(ns user.core
  (:import [io.grpc Server ServerBuilder])
  (:gen-class))

(defonce start-server-atom   (atom nil))
(def port                    8080)

(defn start-server []
  (when-not @start-server-atom
    (reset! start-server-atom
            (-> (ServerBuilder/forPort port)
                (.addService (new user.server.UserAuthenticationServer))
                .build
                .start
                .awaitTermination))))

(defn -main
  [& args]
  (start-server))

server.clj

(ns user.server
  (:gen-class
   :main false
   :name user.server.UserAuthenticationServer
   :extends xyz.skroo.user.UserAuthenticationGrpc$UserAuthenticationImplBase))

(defn -startUserAuthentication [this req res]
  (.onNext res req)
  (.onCompleted res))

It's weird because this was working and I think the compile-time order changed and now I cannot generate a standalone jar.

Answer 1

:profiles {:uberjar {:aot :all}} means that when you run uberjar it will try to compile all Namespaces. When you do lein run it only compiles the namespace in the :aot key.

Try to update the uberjar profile to only aot the server namespace and see if that works.

If not, message me and I'll dig into it deeper