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Clojure on Miren

Clojure isn't auto-detected, so you deploy it with a Dockerfile.miren. This guide uses Ring with the Jetty adapter, run via the clojure CLI and deps.edn.

Let your agent do this

Ask your AI coding agent to "set up this Clojure app on Miren" after installing the Miren agent skills. It adds the Dockerfile.miren, binds Jetty to 0.0.0.0:$PORT, and deploys — using this page as its reference.

Does this source build need a Dockerfile?​

Yes. Miren doesn't auto-detect Clojure, so add a Dockerfile.miren to your project root. Miren builds from it instead of guessing the stack — see Using Dockerfile.miren.

Want native support?

Miren auto-detects and builds common stacks (Python, Node, Bun, Go, Ruby, Rust) without a Dockerfile. This language isn't one of them yet — if you'd like first-class support, request it.

Bind to the injected port​

Miren injects PORT and routes traffic to it, so read PORT and bind 0.0.0.0:

;; src/app.clj — deps.edn searches "src" and the image CMD runs the `app` namespace
(ns app
  (:require [ring.adapter.jetty :as jetty]))

(defn handler [_]
  {:status 200
   :headers {"Content-Type" "text/plain"}
   :body "Hello from Clojure on Miren!\n"})

(defn -main []
  (let [port (Integer/parseInt (or (System/getenv "PORT") "8080"))]
    (jetty/run-jetty handler {:port port :host "0.0.0.0" :join? true})))

A deps.edn with the source path and dependencies:

{:paths ["src"]
 :deps {ring/ring-core {:mvn/version "1.12.2"}
        ring/ring-jetty-adapter {:mvn/version "1.12.2"}}}

The Dockerfile​

Create Dockerfile.miren in your project root. clojure -P downloads dependencies at build time so they're cached in the image:

FROM clojure:temurin-21-tools-deps

WORKDIR /app
COPY deps.edn .
RUN clojure -P
COPY . /app

EXPOSE 8080
CMD ["clojure", "-M", "-m", "app"]

.dockerignore​

.git
.cpcache

Deploy​

The Dockerfile's CMD starts the app. Miren uses it as the web service's startup default, so you don't need a Procfile or service command.

Create .miren/app.toml naming your app and deploy from your project root:

name = "clojure-bench"
miren deploy

For faster startup you can instead build an uberjar (via tools.build or depstar) and run java -jar, but running the clojure CLI directly with cached deps works fine.

Environment variables​

Set variables with miren env set — -e for plain values, -s for secrets (masked in output and logs). Read them with (System/getenv "KEY"):

miren env set -e LOG_LEVEL=info
miren env set -s DATABASE_URL

You can also declare variables in .miren/app.toml:

[[env]]
key = "DATABASE_URL"
value = ""
required = true
sensitive = true

See App Configuration — Environment Variables.

Agent quick reference​

  • Detection: none — requires Dockerfile.miren
  • Base image: clojure:temurin-21-tools-deps; clojure -P caches deps in the build
  • Startup: inherited from the Dockerfile CMD; no Procfile or service command needed
  • Port: (System/getenv "PORT"); run-jetty handler {:host "0.0.0.0"}
  • Env vars: miren env set -e/-s; read with (System/getenv "KEY")

Next steps​