Updated Dockerfile linting

.dockerfilelintrc

@@ -1,6 +1,6 @@
 ---
 rules:
-  apt-get_missing_rm: off
-  apt-get_recommends: off
   apt-get-upgrade: off
+  apt-get-update_require_install: off
+  apt-get_recommends: off
   sudo_usage: off

.yamllint.yaml

@@ -0,0 +1,7 @@
+extends: default
+
+rules:
+  # 80 chars should be enough, but don't fail if a line is longer
+  line-length:
+    max: 80
+    level: warning

Dockerfile

@@ -1,6 +1,6 @@
-FROM ubuntu
+FROM ubuntu:22.04
 
-RUN apt-get -y update && apt-get -y upgrade
+RUN apt-get -y update && apt-get -y upgrade && rm -rf /var/lib/apt/lists/*
 # The following is necessary to avoid an interactive prompt when installing r-base
 RUN DEBIAN_FRONTEND=noninteractive TZ=Etc/UTC apt-get -y install tzdata
 # instructions here: https://www.rstudio.com/products/shiny/download-server/ubuntu/
@@ -19,7 +19,7 @@ RUN gdebi --n shiny-server-1.5.19.995-amd64.deb
 RUN rm /srv/shiny-server/*
 
 # overwrite the default config with our modified copy
-COPY shiny-server.conf /etc/shiny-server/shiny-server.conf 
+COPY shiny-server.conf /etc/shiny-server/shiny-server.conf
 RUN chmod 777 /etc/shiny-server/shiny-server.conf
 
 # This is the app folder specified in shiny-server.conf
@@ -44,4 +44,4 @@ ENV SHINY_LOG_STDERR=1
 ENV SHINY_LOG_LEVEL=TRACE
 
 # start up the server
-CMD ["./startup.sh"]
+CMD ["./startup.sh"]

README.md

@@ -1,6 +1,6 @@
 # shiny-base
 Base Docker image for Shiny applications
 
-Note that this is built on the free version of Shiny Server.  
-For an industrial strength version, consider [Posit/R-Studio Connect](https://posit.co/products/enterprise/connect/), 
-available as a [Docker container](https://hub.docker.com/r/rstudio/rstudio-connect).
+Note that this is built on the free version of Shiny Server.
+For an industrial strength version, consider [Posit/R-Studio Connect](https://posit.co/products/enterprise/connect/),
+available as a [Docker container](https://hub.docker.com/r/rstudio/rstudio-connect).

shiny-server.conf

@@ -1,8 +1,8 @@
 # Instruct Shiny Server to run applications as the user "shiny"
 run_as shiny;
 
-# enable local app configurations using a file named .shiny_app.conf. 
-# This file can be placed within an application directory (alongside the server.R and ui.R files) 
+# enable local app configurations using a file named .shiny_app.conf.
+# This file can be placed within an application directory (alongside the server.R and ui.R files)
 allow_app_override true;
 
 # Define a server that listens on port 3838