Shiny App for testing run_as -- just displays the user the R process is running as.

server.R

library(shiny)

# Define server logic required to generate and plot a random distribution
shinyServer(function(input, output) {
   
  # Expression that generates a plot of the distribution. The expression
  # is wrapped in a call to renderPlot to indicate that:
  #
  #  1) It is "reactive" and therefore should be automatically 
  #     re-executed when inputs change
  #  2) Its output type is a plot 
  #
  output$text <- renderText({
    Sys.info()["user"]
  })
  
})

ui.R

library(shiny)

# Define UI for application that plots random distributions 
shinyUI(pageWithSidebar(
  
  # Application title
  headerPanel("Hello Shiny!"),
  
  # Sidebar with a slider input for number of observations
  sidebarPanel(
  ),
  
  # Show a plot of the generated distribution
  mainPanel(
    verbatimTextOutput("text")
  )
))