adding the application logs to the stdout (#43)

* add xtail package installation

* redirect application-level logs to stdout

* add switcher for app-logs-to-stdout feature; update README.md

* push app logs to stdout by default

Dockerfile

@@ -8,6 +8,7 @@ RUN apt-get update && apt-get install -y \
     libcurl4-gnutls-dev \
     libcairo2-dev \
     libxt-dev \
+    xtail \
     wget
 
 # Download and install shiny server

README.md

@@ -52,7 +52,10 @@ docker run --user shiny -p 3838:3838 --rm rocker/shiny
 
 ### Logs
 
-As of January 2017, the Shiny Server log is written to `stdout` and can be viewed using `docker logs`. The logs for individual apps are in the `/var/log/shiny-server` directory, as described in the [Shiny Server Administrator's Guide]( http://docs.rstudio.com/shiny-server/#application-error-logs)
+The Shiny Server log and all application logs are written to `stdout` and can be viewed using `docker logs`.
+
+The logs for individual apps are still kept in the `/var/log/shiny-server` directory, as described in the [Shiny Server Administrator's Guide]( http://docs.rstudio.com/shiny-server/#application-error-logs). If you want to avoid printing the logs to STDOUT, set up the environment variable `APPLICATION_LOGS_TO_STDOUT` to `false` (`-e APPLICATION_LOGS_TO_STDOUT=false`).
+
 
 ### With docker-compose
 

docker-compose.yml

@@ -14,6 +14,9 @@ services:
     # run on the localhost:80 "Welcome to Shiny" diagnostics page mentioned
     # below.
     user: 'root'
+    # Uncomment the lines below to disable application logs STDOUT output
+    # environment:
+    #   - APPLICATION_LOGS_TO_STDOUT=false
     ports:
       - '80:3838'
     volumes:

shiny-server.sh

@@ -4,4 +4,13 @@
 mkdir -p /var/log/shiny-server
 chown shiny.shiny /var/log/shiny-server
 
-exec shiny-server 2>&1
+if [ "$APPLICATION_LOGS_TO_STDOUT" = "false" ];
+then
+    exec shiny-server 2>&1
+else
+    # start shiny server in detached mode
+    exec shiny-server 2>&1 &
+
+    # push the "real" application logs to stdout with xtail
+    exec xtail /var/log/shiny-server/
+fi