shiny-cloudrun/

[utterances-bot]

Shiny on Google Cloud Run - Scale-to-Zero R Web Apps · Mark Edmondson

How to create scale-to-zero Shiny apps on Google Cloud Run: pitfalls, how and why

https://code.markedmondson.me/shiny-cloudrun/

[noamanemobidata]

Hello Mark! Thank you for this great work! I see that google cloud run supports WebSockets since June 22, 2021 : https://cloud.google.com/run/docs/release-notes#June_22_2021

I try to use this service to host a simple app that display a google map :

library(shiny)
library(googleway)
ui <- fluidPage(
  google_mapOutput(outputId = "map", height = "800px")
)

server <- function(input, output){

  mapKey <- "****"
  output$map <- renderGoogle_map({
    google_map(key = mapKey) %>%
      add_drawing(drawing_modes = c("circle"))
  })

  observeEvent(input$map_circlecomplete, {
    print(input$map_circlecomplete)
  })
}

shinyApp(ui = ui, server = server, options = list(port =as.integer(Sys.getenv('PORT')), host = "0.0.0.0"))

with this Dockerfile :

FROM rocker/shiny

RUN apt-get update -y && apt-get install -y libssl-dev libmariadbclient-dev libxml2-dev libpq-dev libv8-dev libjpeg-dev libjq-dev libsodium-dev

COPY [".", "./"]

RUN R -e  "install.packages('shiny')"
RUN R -e  "install.packages('googleway')"

EXPOSE 8080

CMD ["Rscript", "app.R"]

The app runs But I get this Error : Static path must not have trailing slash

[MarkEdmondson1234]

Hi! Not come across this before, I suspect its a URL hardcoded in the R package you are using (googleway) that ends with / ? I don't think its specific to Cloud Run, unless you say its running fine on other platforms? It would be good to narrow down exactly where the error is occuring - in the R excution or in the Cloud Run backend etc.

If it is a platform issue, you may also need to look at making sure the websocket ports etc are open in your Shiny configuration.

Hope that helps!

[noamanemobidata]

It works in shinyapps.io, I fixed the issue and it works in Cloud Run also ( problem with Dockerfile )

FROM rocker/shiny:4.0.5

RUN apt-get update && apt-get install -y \
    libcurl4-gnutls-dev \
    libssl-dev

RUN R -e  "install.packages('shiny')"
RUN R -e  "install.packages('googleway')"

COPY shinyserver.config /etc/shiny-server/shiny-server.conf
COPY app.R /srv/shiny-server/app.R

EXPOSE 8080

USER shiny

# run app
CMD ["/usr/bin/shiny-server"]

[MarkEdmondson1234]

Ok great! What is in the shiny-server.conf file that fixes it?

[noamanemobidata]

I changed the way of runing the app ( from CMD ["Rscript", "app.R"] to CMD ["/usr/bin/shiny-server"] )... which caused another problem : I have some environment variables in CLoud Run but the shiny user can't access it

[MarkEdmondson1234]

Yeah thats a general gotcha for Shiny apps in general - they don't read environment arguments.

[MarkEdmondson1234]

Found this video the other day which includes a demo of adding IAP to your app so its protected behind a Google login: https://youtu.be/uu97P0IWsO0

[MarkEdmondson1234]

And also note there is now sessionAffinity setting which will try to route users to the same container, which may take away some of Joe's concerns in the article https://cloud.google.com/run/docs/configuring/session-affinity

[noamanemobidata]

Thank you Mark! Since Shiny is statful, I'm using Redis to store user sessions as explained here : https://www.youtube.com/watch?v=mgTI-paDNQ4&ab_channel=GoogleCloudTech

[MarkEdmondson1234]

Oh interesting, so you have R code that stores the Shiny session state? Do you know of any example code? I wonder if with this sessionAffinity flag is available now that you still need to do that?