Chrome browser does not display page unless already open in Shiny

Question

I am able to launch the shiny app when chrome browser is already open in my desktop (linux). However, with my browser closed, and I launch the shiny app, it just shows a blank page and "waiting 127.0.0.1 ..." in lower status bar. In other words, it launches chrome but does not show the shiny app content. Here is my code:

library(shiny)
library(shinyBS)

launch.browser = function(appUrl, browser.path='/usr/bin/chromium-browser') {
  system(sprintf('"%s" --disable-gpu --app="data:text/html,<html>
<head>
<title>Configuration</title>
</head>
<body>
<script>window.resizeTo(800,500);window.location=\'%s\';</script>
</body></html>"', browser.path, appUrl))
}

shinyApp(

  ui = fluidPage(
    fluidRow(
      br(),
      wellPanel(
        fluidRow(
          h4('User Information')
        ),
        fluidRow(
          column(4,
            textInput('Name', 'Full Name', value = "")
          ),
          column(4,
            numericInput('accNum', 'Account Number', value = "")
          ),
          column(4,
            textInput('token', 'Account Token', value = "")
          )
        )
      )
    ),

    fluidRow(
      column(12,
         actionButton('save', 'Save')
      )
    ),
    bsTooltip(id = "accNum", title = "Enter Lending Club account number", 
              placement = "bottom", trigger = "hover")
    # tags$head(tags$style(type="text/css", "#accNum {width: 100px}"))
  ), 

  server = function(input, output, session) {
    session$onSessionEnded(function() {
      stopApp()
    })
    observe({
      if (input$save == 0)
        return()
      isolate({
        j<<-input$accNum
      })
    })

  },
  options = list(launch.browser=launch.browser)
)

Thanks for any help

* Edit 1 *

I have verified that the browser starts fine and goes to a specified URL outside of shiny:

system('/usr/bin/chromium-browser --disable-gpu --app="data:text/html,<html>
<head>
<title>Configuration</title>
</head>
<body>
<script>window.resizeTo(800,500);window.location=\'http://www.facebook.com\';</script>
</body></html>"')

The above also works inside shiny using the location facebook.com. However, when I change it to appUrl parameter it never connects. I also verified that the source of the page is pointing to the correct 127.0.0.1:3189, however, it looks like shiny is not responding for some reason...

What if, from code, you launch chrome then launch the app inside that window? I assume 127.0.0.1 is your local machine or the machine your shiny app is running on? — CalebB
Thanks for the suggestion, but I would prefer not having to do a work around. Shiny should be able to start the browser based on the documentation I have read. However, there is something is causing it to not start even though the same launch command works fine outside of Shiny — John Richardson

John Richardson John Richardson · Accepted Answer · 2014-12-23T14:46:45

Answered by shiny github folks:

"This is due to a problem with your shell script.

You need to add & to run the browser in the background. Otherwise, after R launches the browser, the browser won't return control back to R until after the browser process ends.

The reason it's not a problem when chromium is already open is because chromium responds differently to the command if the browser is already open -- it always returns immediately, even if the command doesn't have &."

Update

Here is the exact script I use:

launch.browser = function(appUrl, browser.path=path) {
  system(sprintf('"%s" --disable-gpu --app="data:text/html,<html>
    <head>
    <title>System Configuration</title>
    </head>
    <body>
    <script>window.resizeTo(830,675);window.location=\'%s\';</script>
    </body></html>" &', browser.path, appUrl))
}

Chrome browser does not display page unless already open in Shiny

2 Answers

Update