init R support

images/R/Dockerfile

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+FROM r-base
+
+RUN echo 'install.packages(c("jug", "jsonlite"), repos="http://cran.us.r-project.org", dependencies=TRUE)' > /tmp/packages.R \
+    && Rscript /tmp/packages.R
+
+COPY . /usr/local/src/fx
+WORKDIR /usr/local/src/fx
+
+CMD ["Rscript", "app.R"]
+EXPOSE 3000

images/R/app.R

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+library(jug)
+library(jsonlite)
+source('./fx.R')
+
+jug() %>%
+    post("/", function(req, res, err) {
+             input <- fromJSON(req$body)
+             fx(input)
+    }) %>%
+    simple_error_handler_json() %>%
+    serve_it(port = 3000)

images/R/fx.R

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+fx <- function(input) {
+    return (strtoi(input$a) + strtoi(input$b))
+}