I get "Error in processx::run: System command error" when using orca inside Docker

I am using orca inside a downloadHandler function in an R-Shiny app inside Docker. When I click on the download button to generate and dowonload a plot I get disconnected from the session. Moreover, on the log file I get: Warning: Error in processx::run: System command error

I am using xvfb-run to run orca with a script like this: xvfb-run -a /squashfs-root/app/orca "$@"

Here is a minimal example of the shiny app:

library(shiny)
library(plotly)

ui <- fluidPage(   
         downloadButton('plot_download', 'Download plot')    
)
server <- function(input, output) {
  output$plot_download <- downloadHandler(
    filename = function(){
        plot_file_name<-'plot.png'
    },
    content = function(file) {

      path_split<-unlist(strsplit(file,'/'))
      
      download_path<-paste(path_split[1:length(path_split)-1],collapse='/')
      
      p <- plot_ly(x = 1:10, y = 1:10, color = 1:10)
      
      withr::with_dir(download_path, orca(p, path_split[length(path_split)]))
      
    })}
shinyApp(ui = ui, server = server)

Moreover, when I use orca in the R terminal inside Docker to generate the same plot, it works.

Here is my dockerfile:

# Install R version 3.5
FROM r-base:3.5.0

# Install Ubuntu packages
RUN apt-get update && apt-get install -y \
    sudo \
    gdebi-core \
    pandoc \
    pandoc-citeproc \
    libcurl4-gnutls-dev \
    libcairo2-dev/unstable \
    libxt-dev \
    libssl-dev \
    libpq-dev \
    libgtk2.0-bin \
    libx11-xcb1 \
    libxtst6 \
    libgconf-2-4 \
    libnss3 \
    libasound2 \
    xvfb

# Download and install ShinyServer (latest version)
RUN wget --no-verbose https://s3.amazonaws.com/rstudio-shiny-server-os-build/ubuntu-12.04/x86_64/VERSION -O "version.txt" && \
    VERSION=$(cat version.txt)  && \
    wget --no-verbose "https://s3.amazonaws.com/rstudio-shiny-server-os-build/ubuntu-12.04/x86_64/shiny-server-$VERSION-amd64.deb" -O ss-latest.deb && \
    gdebi -n ss-latest.deb && \
    rm -f version.txt ss-latest.deb
    
# Install R packages that are required
RUN R -e "install.packages(c('shiny', 'devtools', 'processx'), repos='http://cran.rstudio.com/')"

RUN R -e "devtools::install_github('ropensci/plotly')"

COPY orca_xvfb.sh /srv/shiny-server/orca_xvfb.sh
RUN chmod +x /srv/shiny-server/orca_xvfb.sh

# Download install orca (plotly library to download plots)
RUN wget --no-verbose -P /srv/shiny-server/ "https://github.com/plotly/orca/releases/download/v1.2.1/orca-1.2.1-x86_64.AppImage"
RUN chmod +x /srv/shiny-server/orca-1.2.1-x86_64.AppImage
RUN .//srv/shiny-server/orca-1.2.1-x86_64.AppImage --appimage-extract
RUN ln -s /srv/shiny-server/orca_xvfb.sh /usr/bin/orca
# Copy configuration files into the Docker image
COPY shiny-server.conf  /etc/shiny-server/shiny-server.conf
COPY /app /srv/shiny-server/

# Make the ShinyApp available at port 80
EXPOSE 80

# Copy further configuration files into the Docker image
COPY shiny-server.sh /usr/bin/shiny-server.sh

CMD ["/usr/bin/shiny-server.sh"]

I am using the github version of plotly. If I use the CRAN version and I try to download the plot, I get an error message saying that I need a mapbox token.

I really appreciate any help on this.

[0navarro]

Hello, I finally figured it out.

The problem was that the default user that runs the shiny app from the server, shiny, did not have access to the files in /squashfs-root/app/orca. At first I didn´t notice this because the message in the log file does not give any clue about permissions.

Anyway, I fixed the issue by running chown shiny:shiny -R /squashfs-root/ . I hope this helps.

[afrachioni]

Hello! I’m having a similar issue on a headless Ubuntu machine where I’m trying to set up orca to make plotly figures offline:

$ xvfb-run -a orca graph --verbose test_fig.json 
Fontconfig warning: "/etc/fonts/fonts.conf", line 100: unknown element "blank"
gpu process crashed - false
          Chrome version 73.0.3683.121
          Electron version 5.0.1

The process just hangs there after printing this message. orca --version is 1.2.1. Happy to provide any additional information.