Attempt to perform an operation not allowed by the security policy `PDF'

[dcaud]

The error happens when trying to write to a pdf with image_write() on shinyapps.io. I think the Posit needs to change the policy.xml file on their newly updated Ubuntu servers (see https://stackoverflow.com/questions/52998331/imagemagick-security-policy-pdf-blocking-conversion).

Do you have ideas to fix this issue without needing to wait for Posit to make a change?

Here's an example app that reproduces the error:

library(shiny)
library(magick)

ui <- fluidPage(
  titlePanel("Error when downloading as PDF"),

  sidebarLayout(
    sidebarPanel(
      radioButtons("fileType", "Choose File Type:",
                   choices = c("PDF", "JPEG"),
                   selected = "PDF"),
      downloadButton("downloadFile", "Download")
    ),

    mainPanel(
      imageOutput("displayImage")
    )
  )
)

server <- function(input, output, session) {

  img <- image_read("wizard:")

  output$displayImage <- renderImage({
    tmp <- tempfile(fileext = ".png")
    image_write(img, path = tmp, format = "png")
    list(src = tmp)
  }, deleteFile = TRUE)

  output$downloadFile <- downloadHandler(
    filename = function() {
      if (input$fileType == "PDF") {
        paste0("converted_", Sys.Date(), ".pdf")
      } else {
        paste0("converted_", Sys.Date(), ".jpeg")
      }
    },
    content = function(file) {
      if (input$fileType == "PDF") {
        # The write function w/ PDF seems to be at odds with a policy that can be revised.
        image_write(img, path = file, format = "pdf")
      } else {
        image_write(img, path = file, format = "jpeg")
      }
    }
  )
}

shinyApp(ui = ui, server = server)

Related: https://github.com/rstudio/shinyapps-package-dependencies/pull/289#issuecomment-1780301670

[jeroen]

Yeah I don't think it is possible to work around the policy restrictions. I can try to ping the sysadmins...

[jeroen]

I actually thought they had just removed the policy: https://github.com/rstudio/shinyapps-package-dependencies/pull/323

[dcaud]

They definitely removed the policy a while back, but it has reappeared.

[dcaud]

Thanks, jeroen! I think what happened is that they wrote a script to remove policy.xml for Focal that has was included (and updated) to work with Jammy.

[dcaud]

The Posit folks fixed this so new apps launched there do not continue to have this problem.