Add official Dockerfile (#17)

The Dockerfile builds on windows x86, linux x86/arm and mac x86/arm.

It uses a JVM build, which is simpler and more portable than native builds.

---------

Co-authored-by: Seth For Privacy <40500387+sethforprivacy@users.noreply.github.com>

.docker/Dockerfile

@@ -0,0 +1,46 @@
+# Use Ubuntu image for building for compatibility with macOS arm64 builds
+FROM eclipse-temurin:21-jdk-jammy AS BUILD
+
+# Set necessary args and environment variables for building phoenixd
+ARG PHOENIXD_BRANCH=v0.1.4
+ARG PHOENIXD_COMMIT_HASH=04bd430c48b09611ac201d44fe4a25c32aad0a5f
+
+# Upgrade all packages and install dependencies
+RUN apt-get update \
+    && apt-get upgrade -y
+RUN apt-get install -y --no-install-recommends bash git \
+    && apt clean
+
+# Git pull phoenixd source at specified tag/branch and compile phoenixd
+WORKDIR /phoenixd
+RUN git clone --recursive --single-branch --branch ${PHOENIXD_BRANCH} -c advice.detachedHead=false \
+    https://github.com/ACINQ/phoenixd . \
+    && test `git rev-parse HEAD` = ${PHOENIXD_COMMIT_HASH} || exit 1 \
+    && ./gradlew distTar
+
+# Alpine image to minimize final image size
+FROM eclipse-temurin:21-jre-alpine as FINAL
+
+# Upgrade all packages and install dependencies
+RUN apk update \
+    && apk upgrade --no-interactive
+RUN apk add --update --no-cache bash
+
+# Create a phoenix group and user
+RUN addgroup -S phoenix -g 1000 \
+    && adduser -S phoenix -G phoenix -u 1000 -h /phoenix
+USER phoenix
+
+# Unpack the release
+WORKDIR /phoenix
+COPY --chown=phoenix:phoenix --from=BUILD /phoenixd/build/distributions/phoenix-*-jvm.tar .
+RUN tar --strip-components=1 -xvf phoenix-*-jvm.tar
+
+# Indicate that the container listens on port 9740
+EXPOSE 9740
+
+# Expose default data directory as VOLUME
+VOLUME [ "/phoenix" ]
+
+# Run the daemon
+ENTRYPOINT ["/phoenix/bin/phoenixd", "--agree-to-terms-of-service", "--http-bind-ip", "0.0.0.0"]