How to Set Up ShinyProxy to Host Shiny Apps

By: Peter Solymos

Shiny Server is one of the most popular options to host unlimited Shiny web applications and interactive R markdown documents for free.

ShinyProxy comes with lots of free enterprise features, e.g. various
ways of authentication and authorization. It has no limits on
concurrent usage of the deployed applications. When a user runs an
application, ShinyProxy spins up a new container and serves the
application to the user.

The Docker-based workflow comes with some advantages:

user sessions are fully isolated
apps can have different R versions, package versions, and dependencies
updates to one app won't interfere with other apps
monitoring and resource management (RAM and CPU usage) can be done with Docker tooling

This post shows you how you can set up this versatile, robust, and
tested piece of technology to host your Shiny apps!

System Requirements

Provision a virtual machine with your favourite cloud provider. I use
Ubuntu Linux 20.04 in this tutorial. You will need root user access,
root user is usually root (e.g. on DigitalOcean) or ubuntu (e.g. on
AWS). I will assume you have your ssh keypair configured for
passwordless login. Include the internet protocol (IPv4) address of your
server as the $HOST environment variable:

export HOST="159.203.63.9"

ssh root@$HOST

Update the system, install the Java runtime, the Docker Engine CE
(community edition) and Docker Compose:

apt-get -y update
apt-get -y upgrade

apt-get -yq install \
    default-jre \
    default-jdk \
    docker \
    docker-compose

Check that all went according to plan, java -version should return
something like this:

openjdk version "11.0.11" 2021-04-20
OpenJDK Runtime Environment (build 11.0.11+9-Ubuntu-0ubuntu2.20.04)
OpenJDK 64-Bit Server VM (build 11.0.11+9-Ubuntu-0ubuntu2.20.04, mixed mode, sharing)

ShinyProxy needs to be able to connect to the Docker daemon to spin up
the containers for the apps. By default, ShinyProxy will do so on port
2375 of the Docker host. To allow for connections on port 2375, the
startup options need to be edited following the ShinyProxy
guide.

Create a file /etc/systemd/system/docker.service.d/override.conf:

mkdir /etc/systemd/system/docker.service.d
touch /etc/systemd/system/docker.service.d/override.conf

Add the following content (use nano or vim):

[Service]
ExecStart=
ExecStart=/usr/bin/dockerd -H unix:// -D -H tcp://127.0.0.1:2375

Reload the system daemon, then restart and enable Docker:

sudo systemctl daemon-reload
sudo systemctl restart docker
sudo systemctl enable docker

All this is to make sure that the Docker service starts when the system
boots and the system configurations stay the same so that ShinyProxy can
function properly.

To see if Docker is running properly, type sudo service docker status:

● docker.service - Docker Application Container Engine
     Loaded: loaded (/lib/systemd/system/docker.service; enabled; vendor preset: enabled)
    Drop-In: /etc/systemd/system/docker.service.d
             └─override.conf
     Active: active (running) since Wed 2021-07-21 03:55:26 UTC; 36s ago
TriggeredBy: ● docker.socket
       Docs: https://docs.docker.com
   Main PID: 18881 (dockerd)
      Tasks: 9
     Memory: 39.6M
     CGroup: /system.slice/docker.service
             └─18881 /usr/bin/dockerd -H unix:// -D -H tcp://127.0.0.1:2375

Install ShinyProxy

We download and install version 2.5.0 of ShinyProxy. In case of a newer
version, just change the version variable accordingly, check for updates
on the downloads page:

export VERSION="2.5.0"

wget https://www.shinyproxy.io/downloads/shinyproxy_${VERSION}_amd64.deb
apt install ./shinyproxy_${VERSION}_amd64.deb
rm shinyproxy_${VERSION}_amd64.deb

Configure ShinyProxy

ShinyProxy looks for a
configuration
file called application.yml in the /etc/shinyproxy directory. Let's
create this file:

touch /etc/shinyproxy/application.yml

Copy these configs using a command-line text editor:

proxy:
  title: ShinyProxy
#  logo-url: https://link/to/your/logo.png
  landing-page: /
  favicon-path: favicon.ico
  heartbeat-rate: 10000
  heartbeat-timeout: 60000
  port: 8080
  authentication: simple
  admin-groups: admins
  # Example: 'simple' authentication configuration
  users:
  - name: admin
    password: password
    groups: admins
  - name: user
    password: password
    groups: users
  # Docker configuration
  docker:
    cert-path: /home/none
    url: http://localhost:2375
    port-range-start: 20000
  specs:
  - id: 01_hello
    display-name: Hello Shiny App
    description: A simple reactive histogram
    container-cmd: ["R", "-e", "shiny::runApp('/home/app')"]
    container-image: registry.gitlab.com/analythium/shinyproxy-hello/hello:latest
    logo-url: https://github.com/analythium/shinyproxy-1-click/raw/master/digitalocean/images/app-hist.png
    access-groups: [admins, users]
  - id: 02_hello
    display-name: Demo Shiny App
    description: App with sliders and large file upload
    container-cmd: ["R", "-e", "shiny::runApp('/home/app')"]
    container-image: analythium/shinyproxy-demo:latest
    logo-url: https://github.com/analythium/shinyproxy-1-click/raw/master/digitalocean/images/app-dots.png
    access-groups: [admins]

logging:
  file:
    shinyproxy.log

Pull the two Docker images referenced in the configuration file:

docker pull registry.gitlab.com/analythium/shinyproxy-hello/hello:latest
docker pull analythium/shinyproxy-demo:latest

The first one is the familiar Hello
image.
The second one is another simple Shiny app (that you can find in this
GitHub repository) with
coloured random points and a file uploader that prints the size of the
uploaded file.

The last step is to restart the ShinyProxy service so that the new
configuration takes effect:

service shinyproxy restart

Check the status with service shinyproxy status:

● shinyproxy.service - ShinyProxy
     Loaded: loaded (/etc/systemd/system/shinyproxy.service; enabled; vendor preset: enabled)
     Active: active (running) since Wed 2021-07-21 04:22:46 UTC; 10s ago
   Main PID: 19552 (java)
      Tasks: 12 (limit: 2344)
     Memory: 118.9M
     CGroup: /system.slice/shinyproxy.service
             └─19552 /usr/bin/java -jar /opt/shinyproxy/shinyproxy.jar

Admin and user views

You can access your ShinyProxy server at http://$HOST:8080. Visit this
address and log in using the username 'admin' and password 'password' as
defined in the configuration:

Note that the connection is not secure, this is something that can be
addressed later. Once inside, the admin view lists both apps with their
thumbnail images. Click on the links to spin up the apps. Clicking the
'Admin' button to see the active proxies listing the users, app names,
uptime, etc.

Now log out and try logging in with the 'user' / 'password' combination.
You can only find one of the apps listed. This is how we set up access
based on the user groups. This gives great flexibility for managing the
users' access at the application level.

Conclusions

This is the basic setup of ShinyProxy with basic
authentication/authorization. Edit the configuration file, pull new
Docker images with your Shiny apps and enjoy. There is a lot more you
can do to secure the server and set up a custom domain. I will cover
these topics next.