DevOps: Puppet, Docker, and Kubernetes

Looking at the logs of containers

If the container emits logs or output on STDOUT/STDERR, then we can get them without logging into the container.

Getting ready

Make sure the Docker daemon is running on the host and you can connect through the Docker client. You will also need a running container, which emits logs/output on STDOUT.

How to do it…

1. To get logs from the container, run the following command:

   docker logs [-f|--follow[=false]][-t|--timestamps[=false]] CONTAINER
   

2. Let's take the example from the earlier section of running a daemonized container and look at the logs:

   $ docker run -d  fedora /bin/bash -c  "while [ 1 ]; do echo hello docker ; sleep 1; done"
   

How it works…

Docker will look at the container's specific log file from /var/lib/docker/containers/<Container ...