I'm using Cursive and I set aliases to dev, when I run the REPL it does not load the namespace that defined in deps configuration file:
:aliases {:dev {:main-opts ["--init" "src/my/server/core.clj"
"--eval" "(my.server.core/-main)"]}}
I tried this at the command-line and it worked as expected, loading my.server.core and then running its -main function, so I suspect that Cursive is using -R on aliases rather than -A so it is only pulling in :extra-deps and not :main-opts (that's just a guess, I don't use Cursive). My best suggestion is to ask in the #cursive channel on the Clojurians Slack as that is the primary channel for Cursive support (as far as I know).
I'll also highlight Krisztian's comment that you could use "-m" "my.server.core" as your entire :main-opts since -m will load the namespace and run the -main within it.
However, those options are not the same as Leiningen's :init-ns -- what I think you need is:
{:aliases {:dev {:main-opts ["-e" "(require,'my.server.core)"
"-e" "(in-ns,'my.server.core)"]}}}
When you specify :main-opts, that will suppress starting a REPL:
$ clj -A:dev
#object[clojure.lang.Namespace 0x3dddbe65 "my.server.core"]
$
So you need to add -r to tell the Clojure CLI that you also want a REPL started:
clj -A:dev -r
#object[clojure.lang.Namespace 0x433ffad1 "my.server.core"]
my.server.core=> (doc -main)
-------------------------
my.server.core/-main
([& args])
I don't do a whole lot ... yet.
nil
my.server.core=>
Related
I am writing a CLI framework in Clojure called OneCLI. The main center piece of this framework is a function called go! which parses the command line, environment variables, and config files "for you" and runs one of several different user provided functions based on what was provided in those inputs.
Typically, go! is called from the -main function of the user's calling Clojure program. I use my own library, for example, in another "uberjar" style app called zic. The function go! calls System/exit as part of its run, passing it an exit code that comes from the result of the user provided function. This works great "in production", but it also means that I can't run the zic.cli/-main function from the REPL, as whenever I do it calls System/exit and the REPL exits.
Before you ask, running it from the REPL while developing on a raspberry pi avoids the expensive 45 seconds it takes to run lein uberjar/1 minute 30 seconds to run clj -X:depstar uberjar :jar ....
My question is: Is there some var or value I can check as part of Clojure's standard library that tells my OneCLI code whether it's running from the REPL or if it's running from a JAR?
Such a variable would enable me in OneCLI to detect that we're running from a REPL so that it can avoid calling System/exit.
Instead of trying to have one function that magically detects what environment you're running from, it's quite simple to just have two functions that behave differently.
Extract out the shared behavior to a function that is not part of -main. Call it run or whatever.
Have -main call that function, and then call System/exit
When you wish to use the program from a repl, call run instead of -main. It will finish normally, and not call System/exit.
I don't know how to detect if you're running at a REPL. I took a quick look through Clojure's launching code (clojure.main), but I didn't see any hooks to detect whether you're in a REPL compared to something run via clojure -m.
If you're using AOT (like you are in zic) then you could check whether any of the "REPL" variables (*1, *2, *3, and *e) are bound.
;; returns true in a REPL and `clojure -m`, and
;; returns false in an AOT jar file run with java -jar
(bound? #'*1)
This solves your question as it was asked, but I don't love this "magical" mechanism of guessing the programmer's intent. It might work for your use case (given I think AOT saves on startup time, and CLI tools probably want to start quickly), but none of the projects I work on use AOT at all.
Another option to solve your problem in the clojure -m case as well would be to require developers to explicitly opt out of the "exit on completion" behaviour. One way to do that could be to use a property.
(defn maybe-exit [exit-code]
(cond
(= (System/getProperty "onecli.oncompletion") "remain") (System/exit exit-code)
(= exit-code 0) nil
:else (throw (ex-info "Command completed unsuccessfully" {:exit-code exit-code}))))
Using this code, in a development environment you can add
:jvm-opts ["-Donecli.oncompletion=remain"]
to your deps.edn or project.clj file, but leave it out when running "in production". This has the advantage of being more explicit, but the cost is that developers have to be more explicit.
This is an interesting question because it's usually dreadful to put JVM shutdown into a library, but on the other hand a "real app" involves lots of boilerplate that would be great to share... such as hiding the jar's splash gif at the right time, or (re)opening a Windows terminal if the app wants stdio.
Your uberjar will contain clojure.main, so it is quite possible (and useful) to run the REPL in your uberjar (java -cp my-whole-app.jar clojure.main). Therefore, "detecting" clues on the classpath might not help.
Instead, manage JVM-shutdown work in the -main in the namespace that your jar's manifest declares as its Main-Class. That is: if you run it as java -jar my-whole-app.jar, then it should shut everything down properly.
But I do not always want -main to shut everything down, you say. Then you need two -mains. Make a second -main in a different namespace. Let the jar's Main-Class -main do absolutely nothing but (1) delegate to the second main and (2) shut down the JVM at the end. When you're in the REPL, invoke the second -main, the one that won't clobber the JVM. You can factor out most of each -main into a library. If you went "full framework" you could even make the framework own the uberjarring process and the Main-Class.
Every Java JAR file must have the file META-INF/MANIFEST.MF
added. If it isn't present, you cannot be running in a (normal) JAR file. While you could fool this detector by putting a bogus file on the classpath (i.e. in ./resources, for example), it is a reliable way of detecting a normal JAR file.
Problem:
Dependency JAR files are sometimes sloppy and will pollute the classpath with their own META-INF/MANIFEST.MF files, so the presence of any random META-INF/MANIFEST.MF is not enough to determine the answer in the presence of "noise" files. So, you need to check for the existence of your own specific META-INF/MANIFEST.MF file. This is easy to do if you know the Maven values for ArtifactId and GroupId.
In a Leiningen project, the first line of project.clj looks like
(defproject demo-grp/demo-art "0.1.0-SNAPSHOT"
for a group ID of demo-grp and an artifact ID of demo-art. If your file looks like this:
(defproject demo "0.1.0-SNAPSHOT"
then both the group ID and artifact ID will be demo. Your particular MANIFEST.MF will look like
> cat META-INF/MANIFEST.MF
Manifest-Version: 1.0
Created-By: Leiningen 2.9.1
Built-By: alan
Build-Jdk: 15
Leiningen-Project-ArtifactId: demo-art
Leiningen-Project-GroupId: demo-grp
Leiningen-Project-Version: 0.1.0-SNAPSHOT
Main-Class: demo.core
Set up a function using the to ID strings to detect the presence of your particular project MANIFEST.MF:
(ns demo.core
(:require [clojure.java.io :as io])
(:gen-class))
(def ArtifactId "demo-art")
(def GroupId "demo-grp")
(defn jar-file? []
(let [re-ArtifactId (re-pattern (str ".*ArtifactId.*" ArtifactId))
re-GroupId (re-pattern (str ".*GroupId.*" GroupId))
manifest (slurp (io/resource "META-INF/MANIFEST.MF"))
f1 (re-find re-ArtifactId manifest)
f2 (re-find re-GroupId manifest)
found? (boolean (and f1 f2))]
found?))
(defn -main []
(println "main - enter")
(println "Detected JAR file: " (jar-file?))
)
You can now test the code:
~/expr/demo > lein clean ; lein run
main - enter
Detected JAR file: false
~/expr/demo > lein clean ; lein uberjar
Compiling demo.core
Created /home/alan/expr/demo/target/uberjar/demo-art-0.1.0-SNAPSHOT.jar
Created /home/alan/expr/demo/target/uberjar/demo-art-0.1.0-SNAPSHOT-standalone.jar
~/expr/demo > java -jar /home/alan/expr/demo/target/uberjar/demo-art-0.1.0-SNAPSHOT-standalone.jar
main - enter
Detected JAR file: true
Example of "noise" JAR file: If we do a lein clean; lein run, and add a line to our main program
(println (slurp (io/resource "META-INF/MANIFEST.MF")))
we get out:
Manifest-Version: 1.0
Archiver-Version: Plexus Archiver
Built-By: jenkins
Created-By: Apache Maven 3.2.5
Build-Jdk: 1.8.0_111
I have no idea where this is coming from to get on the CLASSPATH.
P.S. for Leiningen JAR files
When using lein to build a JAR file, it always places a copy of the project.clj file at the location:
META-INF/leiningen/demo-grp/demo-art/project.clj
so you could also use this file's presence/absence as a detector.
Update
OK, it looks like the the MANIFEST.MF file is highly dependent on your build tool. See
https://docs.oracle.com/javase/tutorial/deployment/jar/defman.html
https://www.baeldung.com/java-jar-manifest
So, your choices appear to be:
For lein, you can use the above technique.
You could use the REPL trick of *1 from the other answer.
You could always have your build tool include a custom key-value pair in the manifest and then detect that.
Update #2
An alternate answer, and perhaps easier, is to use the lein-environ plugin and environ library (you need both) to detect the environment (assuming you are using lein to create your REPL). Your project.clj should look like:
:dependencies [
[clojure.java-time "0.3.2"]
[environ "1.2.0"]
[org.clojure/clojure "1.10.2-alpha1"]
[prismatic/schema "1.1.12"]
[tupelo "21.01.05"]
]
:plugins [[com.jakemccrary/lein-test-refresh "0.24.1"]
[lein-ancient "0.6.15"]
[lein-codox "0.10.7"]
[lein-environ "1.2.0"]
]
and you need a profiles.clj:
{:dev {:env {:env-mode "dev"}}
:test {:env {:env-mode "test"}}
:prod {:env {:env-mode "prod"}}}
and a namespace demo.config like:
(ns demo.config
(:require
[environ.core :as environ]
))
(def ^:dynamic *env-mode* (environ/env :env-mode))
(println " *env-mode* => " *env-mode*)
And then you get results like:
*env-mode* => dev ; for `lein run`
*env-mode* => test ; for `lein test`
*env-mode* => nil ; from `java -jar ...`
You need to type:
lein with-profile :prod run
to produce
*env-mode* => prod
If I add the following require:
(ns project.core
(:require
[compojure.route :as route])
(:gen-class))
(defn -main [& {:as args}]
(println "hello"))
an do
lein run
I get
Syntax error macroexpanding clojure.core/ns at (ring/util/mime_type.clj:1:1).
((require [clojure.string :as str])) - failed: Extra input spec: :clojure.core.specs.alpha/ns-form
is there a way I can get
"compojure.route not found; not defined; or whatever" e.g. something meaningful?
if I remove it it works fine. e.g. it says Hello
using Leiningen 2.9.4 on Java 14.0.1 OpenJDK 64-Bit Server VM
The project you are using is using very old dependencies. Clojure spec (introduced "recenlty") added macro/compile time checks and the mentioned file there triggers it.
compojure.route actually is found and it then requires its transitive deps. And while going down the chain ring.util.mime-type is required and the version you are using is not ready for current Clojure versions.
Your best bet here is to upgrade your deps. E.g. if you are following a book or if you are using a template this things can happen. If you have lein-ancient installed, it can attempt the update for you. Otherwise your best bet is to start in your project.clj and compare versions (e.g. check clojars).
If the problem still persists, have a look at lein deps :tree and see what is going on with the transtive deps.
How do I start an nREPL from the clj command?
I can't run my project using Lein or Boot because I have an unbalanced paren somewhere, and the reader complains `java.lang.RuntimeException: read-cond starting on line 13 requires an even number of forms.
Things are easier now than they were when the question was posted:
$ clj -Sdeps '{:deps {nrepl/nrepl {:mvn/version "0.5.3"}}}' -m nrepl.cmdline
More details here.
Wrote a gist on how to do this:
clj -Sdeps '{:deps {org.clojure/tools.nrepl {:mvn/version "0.2.12"}}}'
Clojure 1.9.0
user=> (use '[clojure.tools.nrepl.server :only (start-server stop-server)])
nil
user=> (defonce server (start-server :port 7888))
#'user/server
Now you can connect to port 7888 using your remote REPL client. There is probably a way to do this in one line.
Suppose that I have implemented a few functions for some personal calculation at work. I'd like to build a .jar (uberjar) that my colleagues would use too in a REPL, like:
megacorpcalcs.core=> (+ 2 2)
4
megacorpcalcs.core=> (salary 8 0.4)
666$
What code should I type for a REPL to start when the .jar launches?
EDIT: after your comments I've split this answer into 2
1. Running your uberjar with a REPL
Create your uberjar, and start it with:
java -cp /path/to/your/application-X.Y.Z-standalone.jar clojure.main -i #your_application/foo.clj -r
I had to add the -i parameter and point it to one of my clj files in order to get any of my classes in the project to actually load in the repl. There may be a better way to do this, but I haven't found it yet. Without it, you get a standard clojure repl but your application isn't loaded.
Note, you need the # symbol so that it loads from the jar file relative to the classpath (i.e from root of jar).
This should start a repl which you can change namespace and run your application functions in.
Additionally, you can install rlwrap and prepend the java command with it so you can use history and arrow keys sanely.
2. Embedding a REPL server in your application to connect to from another client
You can embed your own repl on startup of your application (e.g. a simple main that just starts a repl instance), and then your users can run your jar file, and separately connect to it with their choice of tool (cider-jack-in, 'lein repl connect ...')
The simple version of this is:
(start-server :port 7890 :handler cider-nrepl-handler)
Substitute the port you want, see below for the appropriate namespaces to import.
Here is a more complete example:
(ns your-app.server
(:gen-class)
(:require [cider.nrepl :refer (cider-nrepl-handler)]
[clojure.tools.nrepl.server :refer [start-server]]))
(def repl-server (atom nil))
(defn create-nrepl-server!
[repl-port]
(println (format "starting nrepl server on port %d" repl-port))
(reset! repl-server (start-server :port repl-port :handler cider-nrepl-handler)))
(defn -main []
;; ...
(let [repl-port 7890]
(create-nrepl-server! repl-port)
(spit ".nrepl-port" repl-port)))
You'll need the following in your project.clj file
:plugins [[cider/cider-nrepl "0.10.0"]] ;; or whatever version you prefer
:dependencies [[org.clojure/tools.nrepl "0.2.12"]]
Once connected to your custom repl, standard rules apply, just change namespace and call your functions.
Is there some built-in functionality or plugin to lein to get a lein console, so for example one could test without waiting every time for JVM to start up.
$ lein console
>>> test
...
>>> test
...
>>> jar
Note: I'd like to trigger test runs myself, not e.g. by watching source files. That's why I'd like to have a lein console.
Clarification: I'm not looking for lein repl. I'd like to have a console where I could run lein task commands.
Older versions of leiningen used to include lein interactive, which behaved much like the feature you are asking for: it opened a shell into which you could type test and have it run lein test from the already-running lein jvm, and so on. This feature was removed in the transition to lein 2.0, I think, and although I don't know why I suspect there was a good reason. Maybe try asking in #leiningen on freenode?
You might want to have a look at grenchman. While it's not a Leiningen console it at least enables reusing of an existing REPL session. From what I gather, usage is as follows:
Move somewhere that is not inside a project and call:
$ lein repl :headless
Within your project directory, use:
$ grench lein <task> <options>
Tasks will be run inside the already spun up Leiningen JVM and the startup overhead should disappear.
Building grenchman seems to be tedious, though, and it is recommended to use one of the precompiled binaries (BUT they are currently not available).
And finally, that page also states:
Grenchman is still very new and may not be fully reliable.
So, good luck, I guess?
One option is to run a repl from leiningen's own jar file.
$ java -cp ~/.lein/self-installs/leiningen-2.5.0-standalone.jar clojure.main
Clojure 1.6.0
user=> (require '[leiningen.core.project :as project] '[leiningen.test :as test])
nil
user=> (def prj (project/read))
#'user/prj
user=> (test/test prj)
lein test org.noisesmith.orsos.load-test
Ran 3 tests containing 3 assertions.
0 failures, 0 errors.
nil
user=> (require '[leiningen.jar :as jar])
nil
user=> (jar/jar prj 'org.noisesmith.orsos)
Compiling org.noisesmith.orsos
Created /media/justin/806084F16084EEEA/clojure/orsos/target/orsos-0.1.0-SNAPSHOT.jar
{[:extension "jar"] "/media/justin/806084F16084EEEA/clojure/orsos/target/orsos-0.1.0-SNAPSHOT.jar"}
user=>
As a baseline, this can run lein tasks without having to restart lein every time. If you also use rlwrap or use nrepl it becomes a bit more usable. As far as I know there is no user friendly tooling around this (though there easily could be).
If you wish to use tasks from lein plugins those can be added to the -cp arg.