Shiny in docker - file permission problem in Rocker/shiny

app.R

ui <- bootstrapPage(
  actionButton("createDir", "Create dir"),
  textOutput("info")
)

server <- function(input, output) {
  observeEvent(input$createDir, {
    dirPath <- paste0(round(as.numeric(Sys.time())))
    dir.create(dirPath)
    output$info <- renderPrint({
      if(dir.exists(dirPath)) {
        return("Dir was succesfully created")
      } else {
        return("Creation of dir failed")
      }
    })
  })
}

# Return a Shiny app object
shinyApp(ui = ui, server = server)