Simple password authentication for a shiny app

shiny-password.R

#
# This is a Shiny web application. You can run the application by clicking
# the 'Run App' button above.
#
# Find out more about building applications with Shiny here:
#
#    http://shiny.rstudio.com/
#

library(shiny)

pok <- F

# Define UI for application that draws a histogram
ui <- fluidPage(
  titlePanel("Shiny Password"),
  
  sidebarLayout(
    position = "left",
    sidebarPanel(h3("sidebar panel"),
                 uiOutput("in.pss"),
                 uiOutput("in.clr")),
    
    mainPanel(h3("main panel"),
              plotOutput("distPlot"))
  )
)

# Define server logic required to draw a histogram
server <- function(input, output) {
  output$in.pss   <-
    renderUI({
      input$pss
      if (pok)
        return(NULL)
      else
        return(textInput("pss", "Password:", ""))
    })
  output$in.clr   <-
    renderUI({
      input$pss
      if (pok)
        return(sliderInput(
          "bins",
          "Number of bins:",
          min = 1,
          max = 50,
          value = 30
        ))
      else
        return(NULL)
    })
  
  observe({
    if (!pok) {
      password <- input$pss
      if (!is.null(password) && password == "pass") {
        pok <<- TRUE
      }
    }
  })
 
  output$distPlot = renderPlot({
    input$pss
    if (pok) {
      # Check for NULL because input$bins is NULL on first rerender after the password input
      if (is.null(input$bins)) {
        return(NULL)
      }
      
      x    <- faithful[, 2]
      bins <- seq(min(x), max(x), length.out = input$bins + 1)
      
      
      return(hist(
        x,
        breaks = bins,
        col = 'darkgray',
        border = 'white'
      ))
    } else {
      return(NULL)
    }
  })
}

# Run the application
shinyApp(ui = ui, server = server)