#Docker syslog format how to

Imagine a Docker image running in background mode. How can we get our logs back in the client console? The direct approach

It returns the containerвЂ™s name, without further piping the containerвЂ™s stdout to the client consoleвЂ™s stdout! The container is completely detached from the client.

The Docker command-line interface sends the command to the Docker daemon.

This is all good, but Docker containers hardly run in interactive mode in production: they mostly do run in detach mode, i.e. Will output something like this: 0: Mon Oct 1 11:23:

Running the container: $ docker run -name logger1 -h logger1 nfrankel/simplelog:1 I=0 while true do echo ' $(date)' i=$((i+1)) sleep 1 done # and print the container hostname as well as the time every second.

This runs the image as expected, and prints output to the stdout of the console.Д¬onsider the following very basic Docker file (the image is available as nfrankel/simplelog:1 if you want to skip creating it yourself), and the referenced log.sh: FROM busybox:latest Interactive vs background runДЄs a newcomer, one may be happy to run containers using an interactive shell: $ docker run image:latest LetвЂ™s go trough the available options, in order to get a nice overview and a solid foundation upon which you can build your own customized system that fits your needs. In fact, inside the same organization, different applications might use different ways of logging. This seems simple enough, but there are multiple ways to achieve that, from the simplest docker logs to more complex setup involving third-party log management tools.Д®very solution has different pros and cons, and not all can be readily applied to oneвЂ™s own applications. The challenge is to make them available outside of the Docker container for consumption. We will focus on the latter, assuming the application already produces relevant logs. We can distinguish performance logging, more related to the containers itself, and application logging, what actually happens at the application level, inside your container. Visibility and tracking are keys to successful deployments, because issues will arise, and you need that precious bit of information to quickly wipe them out of your way. Poor or-even worse-missing logs can transform a simple bug from a common hiccup to nights of debugging.

#Docker syslog format how to

One of the most imperative decisions youвЂ™ll face is how to manage logging. While playing around with Docker on small projects or dev environments is surely entertaining, bringing your container-based application to production brings along critical decisions and challenges.