Detection
migetpacks detects a Clojure application when either of the following files is present in the project root:
project.clj (Leiningen)deps.edn (Clojure CLI/tools.deps)
Version Detection
Clojure Version
Clojure version is resolved in the following priority order:
| Source | Example |
|---|
.clojure-version | 1.11.1 |
project.clj (org.clojure/clojure dependency) | [org.clojure/clojure "1.11.1"] |
deps.edn (org.clojure/clojure) | org.clojure/clojure {:mvn/version "1.11.1"} |
| Default | 1.11.1 |
Leiningen Version
Leiningen version is detected from:
| Source | Example |
|---|
project.clj (:min-lein-version) | :min-lein-version "2.11.2" |
| Default | 2.11.2 |
Java Version
The JDK version used for compilation and runtime is read from:
| Source | Example |
|---|
system.properties | java.runtime.version=21 |
| Default | 21 |
Build Process
migetpacks uses the official clojure:temurin-{java}-lein Docker image which includes Leiningen and the JDK:
# Build stage
FROM clojure:temurin-21-lein AS builder
WORKDIR /build
# Clojure build environment
ENV JAVA_TOOL_OPTIONS="-Dfile.encoding=UTF-8"
ENV LEIN_ROOT=1
# Layer caching: copy project.clj first
COPY project.clj ./
# Download dependencies (cached if project.clj unchanged)
RUN lein deps
# Copy source code
COPY . .
# Build uberjar and cleanup
RUN lein uberjar \
&& rm -rf src/ test/ dev/ resources/public/js/compiled
# Runtime stage
FROM eclipse-temurin:21-jre
WORKDIR /app
COPY --from=builder --chown=1000:1000 /build /app
Uberjar Detection
migetpacks detects custom uberjar names from project.clj:
(defproject myapp "1.0.0"
:uberjar-name "myapp-standalone.jar"
...)
:uberjar-name is specified, migetpacks uses it when configuring the run command.
Run Command
The default run command for Clojure applications:
java -jar target/uberjar/*-standalone.jar
RUN_COMMAND or a Procfile:
web: java -jar target/uberjar/myapp-standalone.jar
JVM Configuration
The following environment variables are set for production:
| Variable | Value |
|---|
JAVA_OPTS | -Dfile.encoding=UTF-8 -XX:MaxRAMPercentage=80.0 -Dclojure.main.report=stderr |
JAVA_TOOL_OPTIONS | -Dfile.encoding=UTF-8 |
Caching
Layer Caching
Dependencies are cached by copying project.clj before the full source:
| Cached Files | Purpose |
|---|
project.clj | Leiningen project definition with dependencies |
| Scenario | Dependency Install |
|---|
| First build | Runs |
| Source code change only | Cached |
| project.clj change | Runs |
BUILD_CACHE_DIR
When BUILD_CACHE_DIR is set, Leiningen and Maven caches persist at:
| Cache Path | Contents |
|---|
| lein cache | Leiningen profiles and plugins |
| m2 cache | Maven repository (.m2) |
DHI Support
Docker Hardened Images are supported for Clojure runtime.
| Stage | Image |
|---|
| Build | clojure:temurin-{java}-lein (official) |
| Runtime | dhi.io/eclipse-temurin:{java} |
DHI Notes
- The build image is always the official Clojure image (DHI does not provide Clojure/Leiningen images).
- Only the runtime stage uses DHI distroless Eclipse Temurin JRE.
- Java version is read from
system.properties (default: 21).
- Runtime images are distroless (no shell).
Example with DHI
docker run --rm \
-v /path/to/clojure-app:/workspace/source \
-v /var/run/docker.sock:/var/run/docker.sock \
-e OUTPUT_IMAGE=my-clojure-app:latest \
-e USE_DHI=true \
miget/migetpacks:latest
Example
docker run --rm \
-v /path/to/clojure-app:/workspace/source \
-v /var/run/docker.sock:/var/run/docker.sock \
-e OUTPUT_IMAGE=my-clojure-app:latest \
miget/migetpacks:latest
With custom JVM options
docker run --rm \
-v /path/to/clojure-app:/workspace/source \
-v /var/run/docker.sock:/var/run/docker.sock \
-e OUTPUT_IMAGE=my-clojure-app:latest \
-e JAVA_OPTS="-Xmx1g -Dclojure.main.report=stderr" \
miget/migetpacks:latest
