Redirecting command output in docker

Question

I want to do some simple logging for my server which is a small Flask app running in a Docker container.

Here is the Dockerfile

# Dockerfile
FROM dre         


        

Answer 1

To use docker run in a shell pipeline or under shell redirection, making run accept stdin and output to stdout and stderr appropriately, use this incantation:

docker run -i --log-driver=none -a stdin -a stdout -a stderr ...

e.g. to run the alpine image and execute the UNIX command cat in the contained environment:

echo "This was piped into docker" |
  docker run -i --log-driver=none -a stdin -a stdout -a stderr \
    alpine cat - |
  xargs echo This is coming out of docker: 

emits:

This is coming out of docker: This was piped into docker