add julia example

julia/Dockerfile

@@ -0,0 +1,14 @@
+FROM docker.io/julia:latest@sha256:32b91d5ff59276c5986b9b35b76b232651d71e8273dcf22ead1593a960ce816e
+
+ENV JULIA_DEPOT_PATH=/home/ces-user/.julia
+
+USER root
+RUN mkdir /safe_data /safe_outputs /scratch
+
+WORKDIR /app
+
+COPY --chmod=0755 src/* .
+
+RUN julia /app/install_packages.jl
+
+ENTRYPOINT ["/app/run_test.sh"]

julia/README.md

@@ -0,0 +1,7 @@
+# TRE Julia example
+
+## Notes
+
+This example is structured as a script `plot_example.jl` that generates a plot, and a bash script `run_test.sh` that executes the plot script and saves the output to `/safe_outputs`. Both files are found under the `src` directory, which is copied inside the container in the `Dockerfile`.
+
+The required packages are installed using the `install_packages.jl` script. Note that it is important to set the `ENV JULIA_DEPOT_PATH` to ensure the packages are installed in the same environment as where the scripts are to be executed.

julia/src/install_packages.jl

@@ -0,0 +1,4 @@
+using Pkg
+
+Pkg.add(["GR", "Plots"])
+Pkg.precompile()

julia/src/plot_example.jl

@@ -0,0 +1,9 @@
+using Plots
+
+# plot some data
+plot([cumsum(rand(500) .- 0.5), cumsum(rand(500) .- 0.5)])
+
+# save the current figure
+savefig("plots.svg")
+# .eps, .pdf, & .png are also supported
+# we used svg here because it respects the width and height specified above

julia/src/run_test.sh

@@ -0,0 +1,7 @@
+#!/bin/bash
+
+# Run example script
+julia plot_example.jl
+
+# Copy output to /safe_outputs
+mv *.svg /safe_outputs