Deploy Clojure to Fly.io: Efficient Multi-stage Docker build to Deploy Clojure Application to Fly.io

Dockerfile

FROM clojure:openjdk-15-tools-deps AS builder

WORKDIR /opt

ADD deps.edn deps.edn
RUN clj -Sdeps '{:mvn/local-repo "./.m2/repository"}' -e "(prn \"Downloading deps\")"
RUN clj -e :ok

COPY . .
RUN clj -e :ok

RUN cd uberdeps && clojure -M -m "uberdeps.uberjar" --deps-file ../deps.edn --target /opt/app.jar

#------  Slim version -----
FROM openjdk:15-slim-buster AS runtime
COPY --from=builder /opt/app.jar /app.jar

EXPOSE 8080
ENV MALLOC_ARENA_MAX=2

ENTRYPOINT ["java", "-cp", "app.jar", "clojure.main", "-m", "your.namespace.core"]

uberdeps__deps.edn

;; this goes in uberdeps/deps.edn (sorry gists do not allow subdirectories)
;; Note: distinct from your deps.edn file.
{:deps {uberdeps/uberdeps {:mvn/version "1.1.4"}}}